1 Geological Survey of Canada, Ottawa, Ontario, K1A 0E8, Canada
2 Centre géoscientifique de Québec, Sainte-Foy, Québec, G1V 4C7, Canada

Surface cores from kettle lakes in the Oak Ridges Moraine document the history of land-use change in a major agricultural/recreational resource area of southern Ontario. Certain cores intersected a unit (up to 1 m in thickness) of sticky, grey clay commonly overlain by a thin unit of soft organic (FeS-rich) mud and underlain by organic lake sediment (gyttja), marl or peat. In North Thompson Lake, the clay deposit extends throughout the entire lake basin where it unconformably overlies peat (nearshore) and lake sediment (offshore). The clay deposit is rich in plant detritus and thus represents a period of accelerated soil erosion, slope-wash, and siltation in the lake as a result of deforestation at the time of European settlement (commencing about 145 years ago). The clay deposit is clear evidence that the early settlers had exploited the Oak Ridges Moraine with little regard for land-use management at the time. Their only goal was to remove the trees and clear the land as rapidly as possible for cultivation. Close to 2.5-, 5- and 50-fold increases in upland herb pollen deposition (grains/cm-2/yr-1), dry bulk density (g/cc) and rates of sedimentation (g/m-2/yr-1), respectively, across the organic/inorganic contact (settlement horizon) at North Thompson Lake attest to the magnitude of this exploitation. Absence of diatoms in the clay deposit confirms siltation was a major factor in the lake as a result of deforestation and soil erosion/deposition. Deforestation also had an adverse effect on the hydrological component of the Oak Ridges Moraine. These and other settlement and post-settlement land-use changes such as the effects of suburbanization in the mid-1900s will be discussed.

EOCENE PALYNOFLORAS, BIOGEOGRAPHY AND CLIMATES OF SEYMOUR ISLAND, ANTARCTICA

Rosemary A. Askin

Byrd Polar Research Center, The Ohio State University, 1090 Carmack Road, Columbus, Ohio 43210, U.S.A.

The Seymour Island Eocene spore and pollen floras reflect Nothofagus-dominated vegetation for the northern Antarctic Peninsula, with conifers, ferns, Proteaceae and other angiosperms. At paleolatitude approximately 64šS, moist temperate climates prevailed. Lower diversity palynofloras in the upper part of the succession are consistent with a cooler Late Eocene. Eocene sedimentary rocks on Seymour Island are included in the La Meseta Formation, a 750 m thick sandy deltaic succession exposed on the northern part of the island. Terrestrial palynomorphs include spores and pollen from land plants, and fungal remains. These are preserved with varying proportions of marine to freshwater algae (dinoflagellate cysts, acritarchs, prasinophycean and colonial algae), corresponding to facies differences.
The spore and pollen assemblages reflect a typical southern Eocene flora of Nothofagus, Podocarpaceae, Araucariaceae, Proteaceae, Gunneraceae, Myrtaceae, Epacridaceae, Casuarin-aceae, Liliaceae, with diverse cryptogam spores. Nothofagidites spp. predominate throughout. Conifers are a significant part of the flora, though their pollen occur in lower abundances than Nothofagidites. Proteaceae are relatively common, while other angiosperm taxa are relatively scarce to rare. Some porate, colporate and colpate angiosperm pollen of unknown or uncertain affinities also occur in older (Paleocene or Cretaceous) Seymour sequences, while others are new Eocene species. Tectonic separation of the Antarctic Peninsula from South America during the Eocene prevented active floral interchange; however evolution of new forms in the Antarctic Peninsula area continued, but never reached the peak of innovation seen in the Late Cretaceous. Instead there was an overall diversity decrease.

AN INVESTIGATION OF POLLEN FOCUSSING AND DIFFERENTIAL POLLEN DEPOSITION IN LAKE O'HARA, YOHO NATIONAL PARK,
BRITISH COLUMBIA

Alwynne B. Beaudoin1 and Mel A. Reasoner2

1 Archaeological Survey, Provincial Museum of Alberta, 12845-102nd Avenue, Edmonton, Alberta, T5N 0M6, Canada
2 Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada

We have examined pollen spectra from three discrete intervals, dated by tephras and radiocarbon, in a lake-wide series of nineteen cores from Lake O'Hara, a comparatively large (34.4 ha, 43 m deep) lake situated in the upper subalpine ecozone, Yoho National Park. The three sample sets, which represent three different pollen zones identified in a single core (LOH25), provide pollen assemblages at about 2,350, 6,800, and 10,100 yr BP. We used these spectra to investigate two aspects of pollen accumulation in the lake sediments: (1) whether pollen taxa have been differentially deposited in different parts of the lake basin, and (2) whether the entire assemblage has accumulated more in deeper parts of the basin (an effect that has been called "pollen focussing"). The present surrounding vegetation is coniferous forest. This is reflected in the pollen spectra, which are dominated throughout by the major arboreal taxa, especially Pinus (>50%) and, to a lesser extent, Picea and Abies (generally < 20% each, with greatest values in the upper sample set). Percentages of the ten major taxa in the assemblages show remarkable basin-wide consistency within each sample set, suggesting that in this case a single core provides a representative Late Quaternary pollen record. Multivariate statistical analyses (discriminant function analysis and analysis of variance) on pollen percentage, concentration, and PAR data confirm that sample sets are distinctly different and supports zonation of the pollen record from a single core. Minor components of the assemblages (<1% of the pollen sum), mainly NAP, show great variability within and between sample sets and are therefore unreliable for interpretation of vegetation history. Lack of evidence for differential pollen deposition confirms that qualitative inferences based on major components of the pollen sum are probably trustworthy regardless of core location within the lake basin. We did not find evidence for greater pollen accumulation at deeper water sites, implying that pollen focussing has not been a major process in this lake. The morphology of the lake (steep sides, relatively flat floor) may exert considerable control over this process. Sedimentation rates are variable across the basin at each level, suggesting that pollen concentration and particularly PAR data are not dependable for interpretation of vegetation history from a single core, without much greater chronologic control. Additional details may be found in Beaudoin and Reasoner, 1992, Review of Palaeobotany and Palynology 75:103-131.

DINOFLAGELLATE CYSTS FROM UPPER AND MIDDLE JURASSIC OF THE ALGERIAN SAHARAN PLATFORM

M. Benchabla

CRD Sonatrach, Av. de la Novembre 1, 35000 Boumerdes, Algeria

A palynological investigation of the middle and upper Jurassic in the northern province of the Saharan platform identified forty-five stratigraphical useful dinoflagellate cyst taxa. These have made possible a substantial refinement of previous age assignments. Among the species identified, a number of taxa occur in two wells (BAR.1 and ZGA.1), including Gonyaulacysta jurassica, Meiourogonyaulax spp., Tehamadiniun evittii, Occisucysta balios, Leptodinium subtile, L. mirabile, Epiplosphaera bireticulata, Epiplosphaera spp., Dichado-gonyaulax culmula, Dichadogonyaulax spp., Ctenidodinium ornatum, C. cf. continuum, Ctenidodinium. spp., Systematophora penicillata, S. areolata, S. daveyi, Ellipsoidictyum cinctum and E. gochtii. This dinoflagellate cyst assemblage is compared with the biozonation of marine palynofloras established elsewhere in the Tethys area.

POLLEN ANALYSIS OF UNITED STATES HONEY SAMPLES

Vaughn M. Bryant, Jr.1, John G. Jones2 and Gretchen D. Jones3

1 Palynology Laboratory, Texas A&M University, College Station, Texas 77843-4352, U.S.A.
2 Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Panama
3 USDA, AWPMRU, 2771 F&B Road, College Station, Texas 77845, U.S.A.

Between 1950-1980 the United States Department of Agriculture (U.S.D.A.) began a detailed study of domestic honey produced within all 50 states. The first phase of this project was to conduct chemical analyses of nearly 700 individual honey samples so that various types of chemical patterns and chemical composition categories could be developed for each major type of floral honey produced within the United States. The second phase, scheduled to begin in 1960, was to focus on a detailed study of the pollen composition in each of these samples. However, funding cuts prevented the U.S.D.A. from beginning the second phase of their study.
In 1992, funding from the National Honey Board enabled us to conduct the second phase of this original project. Fortunately, most of the samples had been saved, and we were able to extract pollen from a large portion of those samples. However, we discovered that some of the originally collected samples had been filtered, thus removing all pollen. Nevertheless, we were able to conduct pollen counts from more than 75% of the samples originally tested for their chemical contents.
Our attempt to examine such a diverse group of honey samples collected from a wide range of ecological habitats proved a monumental task. Each of us considered ourselves to be fairly competent palynologists and all of us had extensive experience examining honey samples. However, we soon discovered that trying to identify the great diversity of pollen types found in honey produced in the United States was difficult in spite of our access to a pollen reference collection containing over 12,000 different taxa and the use of micrographs in newly published pollen atlas, Pollen of the Southeastern United States with emphasis on Melissopalynology and Entomopalynololgy (A.A.S.P. Contribution Series # 30). These problems arose because some samples were produced in regions as diverse as high altitude alpine meadows while others came from tropical habitats in Florida, California, and Hawaii.
We present a summary of our findings showing tentative similarities between some specific chemical characteristics and pollen associations. In addition, we verify the need for further studies of honey types produced within the United States. To date, our study is the only attempt at this large a scale that has ever been conducted within the United States. Our study also revealed that the "guesses" made by beekeepers and producers as to the floral types in the samples were mostly incorrect, thus confirming our assumption that correct identification of honey floral components must be linked to precise pollen sampling.

MICROSCOPIC CHARCOAL: A PRELIMINARY ATLAS OF SCANNING ELECTRON MICROGRAPHS OF
SELECTED CANADIAN BOREAL SPECIES

C. Campbell1 and I.D. Campbell2

1 Department of Geography, University of Alberta, Edmonton, Alberta, T6G 2H4, Canada
2 Canadian Forest Service, 5320-122 St. Edmonton, Alberta, Canada, T6H 3S5, Canada

Although large charcoal particles are routinely identified in paleoecological and archaeological studies, microscopic charcoal in paleoecological studies has mainly been quantified only, with little attempt at identifying the species which burned. An atlas of common features in microscopic charcoal fragments from selected Canadian woody boreal species demonstrates the potential for identifying as well as quantifying charcoal fragments in lake sediments or other deposits. In many cases it may be possible to distinguish the dominant fuel type in past fires, considerably adding to the paleoecological value of the charcoal. Although scanning electron micrography is best, many of the relevant features are also visible by light microscopy.

EXPERIMENTAL POLLEN PRESERVATION:
SUSPENSION SALINITY

I. D. Campbell

Canadian Forest Service, 5320-122 St. Edmonton, Alberta T6H 3S5, Canada

Pollen is often found in various states of preservation. Pollen of aspen (Populus tremuloides) has been found to suffer rapid destruction in the water column of freshwater lakes (Hadden, 1978); this has been used to explain the apparent relative dearth of aspen pollen in many sites where aspen is abundant on the landscape. Here, an experiment where aspen and other species of pollen were placed in various concentrations of CaCl2 shows that the rapid destruction of pollen in water is a function of osmotic pressure. There is a marked difference in the severity of damage sustained by pollen in distilled water as compared to pollen in a hypertonic solution; the pollen in the hypertonic solution sustained no appreciable damage. Nevertheless, even in distilled water, the damage was not so severe as to hamper the identification of the pollen. Similarly, there is a marked difference in damage sustained by inaperturate vs. aperturate pollen grains, with the osmotic pressure being relieved through the apertures, thus minimizing damage to the pollen grain. Interestingly, pine (Pinus mugo) pollen is damaged about as severely as the aspen pollen. This suggests that the general underrepresentation of aspen in the aspen parkland of western Canada is unrelated to aspen destruction. An alternate explanation is that the aspen parkland is itself a recent development; it may be that many of the cores taken in the 1960s, when the parkland was lass than 100 years old, did not collect the upper few centimetres of unconsolidated sediment, and thus missed the aspen signal.

PALYNOLOGY OF THE ST. LAURENT FERRY FEN, IN THE GRASSLAND NEAR SASKATOON, SASKATCHEWAN

I.D. Campbell1, S.C. Zoltai1, and D.D. Delorme2

1 Canadian Forest Service, 5320-122 St. Edmonton, Alberta T6H 3S5, Canada
2 Canadian Centre for Inland Waters, P.O. Box 5050, Burlington, Ontario L7R 4A6, Canada

St. Laurent Ferry Fen is a small, spring-fed wetland near Saskatoon, Saskatchewan, in the grassland well south of the forest margin; it is the most southerly fen known in this region. A 3.3 m core spanning some 4,000+ years shows a record of rapid moistening, with prairie elements reducing rapidly in the first few cm, then continuing to decline until EuroCanadian disturbance. The site was initially fringed with shrub birch, which rapidly declined and was replaced in part by willow and sedges. Conifers arrived at the site fairly early in the record. The ostracods and sedge pollen both agree that there were strong fluctuations in moisture throughout the last 4,000 years, but the general trend shown by the regional pollen is toward increasing moisture. It is likely that both the ostracods and the sedges are responding to minor water-table fluctuations superimposed on the tendency of the fen to maintain itself at or close to the ground water table. Tamarack (Larix laricina) pollen increases ca. 3,500 BP; at the same time, there is the first occurrence of tamarack-like microscopic charcoal.

SEASONAL VARIATION IN THE POLLEN LOAD OF THE ATCHAFALAYA RIVER, U.S.A.

Gail L. Chmura1 and Alexei Smirnov2

1 Department of Geography, McGill University, 805 Sherbrooke St. W, Montreal, Québec H3A 2K6, Canada
2 Department of Earth Sciences, Memorial University, St. John's, Newfoundland A1B 3XS, Canada

We have examined seasonal variability in the pollen load of the the Atchafalaya River, a distributary of the Mississippi River in Louisiana. Three sampling events were scheduled to reflect variability in pollen production, sediment supply, and hydrology (October, March, and June). The suspended pollen load of the river was characterized by concentrating pollen from river water sampled at nine depths on five points (verticals) along a cross section at Morgan City. Monthly records of sediment discharge at the head of the Atchafalaya basin and the river's two outlets to the Gulf of Mexico indicate a pattern of net sediment deposition from late summer to early spring. During rising river stages in spring, sediments are partially scoured from the basin over a period generally concurrent with production of arboreal pollen in the upper reaches of the Mississippi basin, allowing the "northern" pollen to be discharged into the Gulf. Within the sub-tropical Atchafalaya Basin, pollen is produced earlier and deposited along with sediments held within the Basin. This sedimentary regime has considerable import for interpretation of pollen assemblages of fluvio-marine sediments in the Gulf of Mexico which should be representative of the vegetation of the Mississippi drainage basin and not biased by coastal vegetation. In major rivers running east-west we expect pollen production and transport to be synchronous, but inputs to north-flowing rivers may show a pattern similar to that of the Mississippi, if periods of high discharge precede blooming of coastal vegetation.

SYNTHESE PALYNOSTRATIGRAPHIQUE DU
PLEISTOCENE SUPERIEUR DE LA VALLEE
DU SAINT-LAURENT (QUEBEC)

Martine Clet-Pellerin

CNRS - URA 1694, Géomorphologie, 24, rue des Tilleuls,
F-14000 Caen, France

Un modèle stratigraphique d'ensemble du Quaternaire de la Vallée du Saint-Laurent est proposé pour évaluer la nature, la position et la chronologie de différentes unités regroupées en séquences sédimentaires à commande climatique. L'analyse palynologique systématique associée à un inventaire lithostratigraphique permet de présenter l'évolution générale des paléoenvironnements végétaux, liée à la dynamique de sédimentation dans la vallée et l'estuaire pendant le Pléistocene supérieur. Différentes unités nouvelles ont été répertoriées et une colonne biostratigraphique est établie pour servir de référence. Aprés la glaciation de l'Illinoien, la toundra est colonisée par une forêt boréale dans la phase d'afforestation. Cette forêt se transforme progressivement en sapinière jusqu'à l'optimum climatique du Sangamonien caractérisé par l'accroissement de Quercus et d'autres arbres thermophiles (forage de l'île aux Coudres). Après un épisode d'érosion fluviatile, la détérioration climatique entraine de nouveau l'appauvrissement du couvert végétal avant le phénomène d'englaciation (Sables de Lotbinière et Varves de Deschaillons) jusqu'à un épisode glaciaire moins important que l'Illinoien. Et de nouveau, les sédiments marins sont présents dans la vallée (Mer de Cartier) mais les paysages sont déjà recouverts d'une forêt boréale ouverte, le stade de la toundra n'ayant sans doute pas existé. Après une nouvelle érosion fiuviatile et le dépôt des Sédiments de Saint-Pierre, un léger réchauffement favorise la croissance d'une sapinière et de quelques arbres thermophiles (rythmites du Saint-Maurice). Ultérieurement la forêt boréale s'appauvrit jusqu'à l'apparition d'une toundra et la glaciation du Wisconsinien. L'originalité de cette démarche a permis de prendre en compte des milieux sédimentaires aussi variés que sédiments marlns, fluviatiles, lacustres, glaciaires et d'intégrer à cette analyse séquentielle les différentes origines des sources polliniques pour une interprétation des paléoenvironnements à l'échelle sub-continentale.

PRE-COLUMBIAN HUMAN IMPACT ON THE
WETLANDS OF THE SOUTHWESTERN U.S.A.

Owen K. Davis

Department of Geosciences, University of Arizona, Tucson, Arizona 85721, U.S.A.

Wetlands are rare in the desert Southwest, and they have received intense human utilization throughout prehistoric and historic times. Comprehensive studies of eight marshes (cienegas) in California, Arizona, New Mexico, and Sonora show a consistent pattern of following European settlement:
1) the introduction of exotic weeds and the expansion of certain upland taxa
2) the marked expansion of wetland taxa, particularly trees
3) the decreased abundance of charcoal fragments in the sediment
4) increased percentages of fungal spores
5) the transition of sediment from silts to peat
These changes suggest a dramatic decrease in the frequency and intensity of marsh fires after European settlement. Prior to the historic period, burning was frequent enough to maintain open, herb-dominated cienegas, and intense enough to eliminate the build-up of dead plant tissue. Following fire suppression, bulrushes and woody plants were able to invade the cienegas, and the buildup of senescent plant tissue resulted in the accumulation of organic sediment (peat) and the increased abundance of decay fungi.

NEEDLES IN THE HAYSTACKS: THE OLIGOCENE-MIOCENE BOUNDARY IN THE EASTERN CARPATHIANS OF ROMANIA

Thomas D. Demchuk1 and Sarah P. Damassa2

1 Amoco Exploration and Production Technology, Biostratigraphic Support and Development Section, P.O. Box 3092, Houston, Texas 77253-3092, U.S.A.
2 Consultant, 3 Ridge Street, Winchester, Massachusetts 01890, U.S.A.

Palynological investigations of Oligocene and Miocene strata from the Eastern Carpathians of Romania demonstrate the need for and the benefits of cooperative efforts combining palynological, calcareous nannofossil and foraminiferal study in order to biostratigraphically subdivide these strata, and to identify the Oligocene-Miocene boundary. Strata of the Eastern Carpathians are dominated by carbonaceous shales, initially deposited as turbidites and later complexly folded and faulted, resulting in difficult lithostratigraphic correlations. Previous multi-disciplinary paleontological research interpreted this boundary as being conformable, with the lowermost Miocene (Aquitanian) being absent. Seven sections believed to contain the Oligocene-Miocene boundary were sampled and analyzed for all three groups of microfossils.
Palynologically, the Early Oligocene (Rupelian) dinoflagellate assemblages are characterized by Deflandrea spp., Distatodinium spp., Homotryblium spp., Rhombodinium draco and Wetzeliella spp. Few Late Oligocene (Chattian) strata have been identified but, where present in a seemingly continuous section, they can be identified by the last occurrences of such taxa as Samlandia chlamydophora and Phthanoperidinium comatum Characteristically, foraminifera are almost always absent from these Oligocene strata. The calcarerous nannofossil assemblages are not always age-diagnostic within the Chattian.
Early Miocene dinoflagellate assemblages are unique in that there is a distinct lack of in-situ taxa; the assemblages are comprised of re-worked Oligocene forms with very few characteristic Miocene taxa present, which include Ectosphaeropsis burdigalensis and Unipontidinium downiei. In the absence of these Miocene markers, the assemblages can very easily be interpreted as Oligocene in age. Late Burdigalian strata are characterized by the last occurrences of Distatodinium craterum, Cordosphaeridium cantharellus and Palaeocystodinium golzowense. Only through the investigation of the calcareous nannofossils and foraminifera though, can the Early Miocene be recognized and confirmed.

DINOFLAGELLATE CYSTS AS A NEW BASIS FOR CORRELATION IN THE BRACKISH BASINS OF THE EASTERN PARATETHYS REGION

Thomas D. Demchuk and Jeffrey A. Stein

Amoco Exploration and Production Technology,
Biostratigraphic Support and Development Section,
P.O. Box 3092, Houston, Texas 77253-3092, U.S.A.

Strata of latest Miocene (Meotian) through earliest Pliocene (Dacian) age have been interpreted as being deposited in waters with less than normal marine salinity (i.e. salinities of approximately 15 ppt.). Previous biozonations of these strata have relied primarily on ostracodes, charophytes, pollen spectra, and mammalian fossils. Recent detailed research of these strata, however, has revealed the presence of a well preserved and diverse dinoflagellate assemblage which may be endemic to the eastern Paratethyan region. Last and first appearance data of species of cruciform Spiniferites and Nematosphaeropsis, and Thalassiphora-like dinoflagellate cysts correspond closely with the Miocene-Pliocene (Pontian/Dacian) boundary as identified from ostracodes, and this event can be correlated with certainty throughout the eastern Paratethys region (Romania to Azerbaijan).
Strata of the latest Miocene (Pontian) are characterized by the last appearance datums of Systematophora placacantha, Thalassiphora sp. A of Powell (1986) and an undescribed species of cruciform Nematosphaeropsis. Subsequently, the earliest Pliocene (?) is characterized by the first appearance of Spiniferites cruciformis and S. inequalis. Other dinoflagellates present include Hystrichosphaeropsis obscura, Selenopemphix armageddonensis, Achomosphaera andalousiensis, and previously undescribed species of Corrudinium and Thalassiphora.

DINOFLAGELLATE CYSTS FROM THE KIRMAKY SUITE (LATE MIOCENE-PLIOCENE), APSHERON PENINSULA, AZERBAIJAN

C. N. Denison

Chevron Overseas Petroleum Inc., P.O. Box 5046, San Ramon, California 94583-0946, U.S.A.

The Productive Series is the main reservoir interval on the Apsheron Peninsula, and offshore in the Apsheron Sill and adjacent areas of the Azerbaijan sector of the Caspian Sea. Samples of the type Kirmaky Suite (late Miocene-Pliocene), the lowermost unit of the Productive Series, were collected during reconnaissance fieldwork north of the capital city, Baku. During deposition of the Kirmaky Suite, the Caspian was much reduced in size, and the paleo-Volga delta was depositing sand in the Apsheron Peninsula and Apsheron Sill areas.
In situ specimens are usually in the minority. All in situ species are associated with reduced salinity conditions; Spiniferites cruciformis is the most distinctive element. Specimens recycled from Russian Platform sediments dominate the assemblages. In the lower part of Kirmaky Suite, Paleogene, particularly Eocene, species form the majority of the assemblages, although a Late Cretaceous component is present. Towards the top of the Kirmaky Suite, Late Cretaceous species are more prevalent.

THE ROLE OF DINOFLAGELLATE CYST
STRATIGRAPHY AND PALYNOFACIES IN
OLIGOCENE-MIOCENE SEQUENCE ANALYSIS,
ODP NEW JERSEY TRANSECT

Laurent de Verteuil and Geoffrey Norris

Department of Geology, University of Toronto, 22 Russell St., Toronto, Ontario M5S 3B1, Canada

The New Jersey Transect is a joint ODP, NSF and USGS funded drilling program to investigate Oligocene to Recent sea-level history and clastic sequence stratigraphy on a mature, divergent margin. ODP Leg 150 recovered cores from four sites on the continental slope, and complimentary drilling in the adjacent coastal plain has been completed at three sites in New Jersey, spread over 250 km along depositional strike. More than 15 reflector surfaces on the shelf and slope, within a dense grid of multichannel seismic lines, have been mapped by project participants. To complete the transect, drilling of a dip-oriented series of shelf sites is planned. Palynological studies, and dinocyst stratigraphy in particular, are making an integral contribution to the central objectives of this project, from age determinations, through site-to-site correlations, to paleoenvironrnental analysis and systems tract interpretations.
The primary objective of slope drilling was to bracket the ages of reflector surfaces at their distalmost expression, where associated hiatuses are predicted to be of least duration. Dinocyst assemblages are diverse and well preserved in the Oligocene to Recent sections at all the slope sites and provide excellent site-to-site correlation. Indirect correlation of dinocyst horizons with numerical and geomagnetic polarity scales establishes a framework for dating the sequences present at each site. Palynofacies results from Site 904 indicate a shift in dominance of maceral types, beginning in the lower middle Miocene, from marine amorphous organic matter to non-marine phytoclasts. This change coincides with the onset of second order sea-level lowering, previously documented in numerous oxygen isotopic studies. Palynofacies also responded to second order sea-level change in the upper Miocene.
Onshore drilling at Cape May and Atlantic City recovered thick upper Oligocene and lower Miocene sequences with well developed systems tracts. These sequences are correlated to disconformity bound units on the continental slope using dinocyst stratigraphy. Preliminary results suggest differing preservation records and styles between the onshore and slope sites.

OLIGOCENE AND MIOCENE DINOCYSTS FROM CENTRAL AND SOUTHERN FLORIDA

Lucy E. Edwards

U.S. Geological Survey, 970 National Center, Reston, Virginia 22092, U.S.A.

Detailed study of cores three deep coreholes in central and southern Florida reveals a diverse succession of dinocysts and acritarchs in Oligocene and Miocene sediments. Material from these and over a dozen additional cores adds to the interpretation of the depositional history of the area, where most calcareous fossils are leached.
Lower Oligocene sediments contain well-preserved dinocysts and acritarchs in most cores, and the assemblages resemble classic Gulf Coast assemblages in the presence of Operculodinium placitum, Ascostomocystis potane, and Operculodinium divergens. An upper Oligocene section dominated by Chiropteridium and Wetzeliella species is present in most cores. Thick Miocene successions contain diverse assemblages typically dominated by Systematophora or Cribroperidinium in the lower part and Spiniferites in the upper part. Peridinialean forms, such as species of Multispinula, Selenopemphix, Sumatradinium, and Trinovantedinium are present but not abundant in most Miocene samples.
Records of many of the key events used in biostratigraphic subdivision of the western and eastern North Atlantic margins are found in the Florida material. These events allow for very precise correlations across Florida and to worldwide chronologies. However, significant differences in some ranges do occur, and these represent ecological effects. Some forms, such as Tuberculodinium vancampoae and Chiropteridium spp., apparently have longer ranges in the Florida sediments; others, such as Labyrinthodinium truncatum, have shorter ranges. Abrupt truncations of dinocyst ranges at a single level in a core serve to highlight unconformities in the stratigraphic record. Dinocysts reveal that the whole upper Oligocene section is missing from one core on the Atlantic margin.
The Florida material illustrates the potential of dinocysts for high-resolution chronostratigraphy and for the recognition of dinocyst biogeographic patterns.

PALYNO/CHRONOSTRATIGRAPHIC CORRELATIONS OF EARLY PENNSYLVANIAN STRATA IN SOUTHWESTERN INDIANA, U.S.A.

Donald W. Engelhardt1 and Lloyd C. Furer2

1 Earth Sciences and Resources Institute, University of South Carolina, Columbia, South Carolina 29208, U.S.A.
2 Indiana Geological Survey, Bloomington, Indiana, U.S.A.

Well-preserved and abundant miospores were recovered and identified from samples in five core holes and five outcrops from the Mansfield Formation of the Pennsylvanian Morrowan Series in southwestern Indiana. The samples are from Daviess and Martin Counties, Indiana, in the eastern portion of the Illinois Basin. The palynomorphs aid in the correlation and age differentiation of the Pennsylvanian rocks below the Desmoinesian cyclothems. The palynofloras are comparable to those reported from the Caseyville and Kilbourn formations of Iowa and the Caseyville and Abbott rocks in Illinois. These formations are considered to be Morrowan and Atokan by Ravn and Peppers. The stratigraphic ranges of some of the taxa are modified by this study. For example, Anafoveosporites avcinii extends higher in the Atokan age sediments than previously reported.
Guennel used the term Pottsville Series for his studies on the Mansfield and Brazil formations in Indiana. He did not utilize the standard Midcontinent Pennsylvanian chronostratigraphic nomenclature for differentiating the Morrowan and Atokan, which ranges in age from Namurian C to Westphalian B in the European stages. The top of the Morrowan (Westphalian A) has been interpreted by Ravn and Peppers as marked by the extinction of Schulzospora rara. Another miospore that became extinct at this time is Radiizonates striatus. Both of these taxa are present in the deepest shale at 277.2-290' in core hole 27-Kf-2 in Daviess County. We would place the Morrowan/Atokan boundary above this shale near the position of the Pinnick Coal Member of the Mansfield Formation. Several species of Densosporites, rare Lycospora noctuina and common Lycospora pellucida are present along with many taxa reported from the Caseyville Formation. Peppers places the
Morrowan/Atokan boundary just above the St. Meinrad coal in Indiana. The Atokan is characterized by the miospores Vestispora pseudoreticulata, V. fenestrata, frequent Endosporites globiformis, consistent occurrences of Dictyotriletes bireticulatus, and the first occurrences of Triquitrites sculptilus, Radiizonates difformis and Renisporites confossus. A large number of miospore species reported from the Abbott and Kilbourn formations of Illinois and Iowa are present in the shale samples analyzed.
Oil droplets, petrolic filament bodies, are present in several of the shale samples. The thermal alteration index (TAI) is 4/4+ with an interpreted Ro of 0.6. This would place the organic material at early peak oil generation. The Pennsylvanian sediments in this area must have been buried much deeper than at the present time to have this degree of thermal alteration.
The palynologic correlations coincide with extensive chronostratigraphic geophysical log correlations in southwestern Indiana which establishes a tie between the outcrop type sections and the subsurface. The time lines developed by integrating the palynological and geophysical data on the cross sections in Daviess and Martin Counties supports a northerly transgression onlap model for Mansfield Formation deposition.

AN UPPERMOST CAMPANIAN TO LOWER MAASTRICHTIAN ORGANIC-WALLED
PHYTOPLANKTON ASSEMBLAGE FROM THE
CENTRAL ARCTIC OCEAN, CORE FL-533,
ALPHA RIDGE

John V. Firth

Ocean Drilling Project, 1000 Discovery Drive, Texas A&M University Research Park College Station, Texas 77845, U.S.A.

A diverse assemblage (48 taxa) of dinoflagellate cysts, acritarchs and chlorophytes occur in an approximately 70 cm thick layer of black organic rich mud recovered in Core FL-533 from Alpha Ridge, Arctic Ocean, at 85š05.9'N, 98š17.8'W, This marine palynomorph assemblage is mixed with a large amount of terrestrial organic matter and palynomorphs. The assemblage is dominated by Comasphaeridium sp., Veryhachium sp., and Chatangiella biapertura, with common Elytrocysta, Chlamydophorella and Spinidinium clavum. The overall assemblage shows a remarkable similarity with those described from the Campanian to Maastrichian in the Northwest Territories, Canada (McIntyre, 1974, 1975; Doerenkamp et al., 1976). The presence of Comasphaeridium sp. (= Acritarch Form 2; McIntyre, 1974), Cerodinium leptodermum Chatangiella decorosa/coronata, Chatangiella granulifera, Chatangiella amphiata and Deflandrea sp. 2 (McIntyre, 1975), in the absence of strictly upper Maastrichtian or younger taxa indicates that this section is best correlated with the upprmost Campanian to lower Maastrichtian, equivalent to the middle of the 'Pale Shale Zone' of the Horton River section, N.W.T. (McIntyre, 1974, 1975).

NOTHOFAGIDITES IN PLIOCENE MARINE SEDIMENTS AROUND ANTARCTICA

R. Farley Fleming1 and John A. Barron2

1 U.S. Geological Survey, MS 919, Box 25046, Denver, Colorado 80225, U.S.A.
2 U.S. Geological Survey, MS 915, 345 Middlefield Road, Menlo Park, California 94025, U.S.A.

Neogene paleobotanical and palynological records of Antarctic vegetation can provide critical constraints on the climatic evolution of Antarctica. Pliocene wood, leaves, and pollen referable to Nothofagus have been reported from the Sirius Group in the Transantarctic Mountains. However, these reports are controversial due to questions regarding age control of the Sirius Group. The reported absence of palynomorphs in Pliocene marine sediments around Antarctica has been used as evidence to indicate the absence of terrestrial vegetation on Antarctica during the Pliocene.
Abundant siliceous microfossils were recovered in 17 samples of Pliocene sediments from Deep Sea Drilling Program (DSDP) Site 274 (latitude 68š59.81' S., longitude 173š25.64' E.). Detailed biostratigraphic analyses of diatoms and radiolarians in these assemblages indicate that the sampled interval ranges from 5.0 to 2.2 Ma. Palynomorphs were recovered in three samples from this interval in Site 274 The assemblages contain species with stratigraphic ranges that encompass the Pliocene (including Nothofagidites spp.), as well as species that are unequivocally reworked from older rocks. Species of Nothofagidites from Site 274 include N. asperus, N. brachyspinulosus, N. flemingii, N. senectus, and N. sp. cf. N. lachlaniae. Nothofagidites sp. cf. N. lachlaniae is comparable to fossil pollen reported from the Sirius Group. The relative abundance of this form in samples from Site 274 is significantly higher than relative abundances for the other species of Nothofagidites in the same samples, suggesting derivation from trees of Nothofagus living in Antarctica during the Pliocene. However, the possibility of reworking at Site 274 cannot be excluded. Preliminary results from Ocean Drilling Program Site 695 indicate that assemblages from near the Antarctic Peninsula also contain Nothofagidites spp., including N. sp. cf. N. lachlaniae.
Microfossil assemblages recovered from Site 274 and Site 695 indicate that Pliocene marine sediments near Antarctica contain palynomorphs and that the stratigraphic ranges of some of the species do not preclude the possibility that the palynomorphs are Pliocene in age. If the relative abundance of Nothofagidites sp. cf. N. lachlaniae is consistently high in numerous sites from around Antarctica, this pattern would provide corroborative evidence for the presence of Nothofagus in Antarctica during the Pliocene. Detailed palynological investigations of Neogene marine sediments in the Southern Ocean may provide insight into the vegetation history of Antarctica.

THE ECOLOGICAL IMPACT OF THE MID-HOLOCENE TSUGA CANADENSIS DECLINE IN SOUTHERN ONTARIO, CANADA

Janice L. Fuller

Harvard Forest, P.O. Box 68, Petersham, Massachusetts 01366, U.S.A.

Tsuga canadensis was an abundant tree species in the mixed forests that covered north-eastern North Arnerica in the mid-Holocene. Paleoecological evidence suggests that populations of Tsuga canadensis declined dramatically about 4700 C14 years BP. The rapid and synchronous nature of the decline indicates that it may have been due to a pathogenic outbreak. Although this decline has been recorded in many paleoecological investigations, little is known about its ecological impact. Tsuga canadensis is a highly shade-tolerant and long-lived tree species. In areas where is was abundant, many gaps in the forest canopy must have been produced after its demise. This study aims to address the following questions: What was the impact on forest dynamics of the removal of a primary tree species such as Tsuga canadensis? Were there any long-term implications of such an historical event?
Fine resolution fossil pollen data has been obtained from two sites in southern Ontario to examine these questions. A population-modelling approach was adopted to examine the mode and rate of change of selected forest taxa after the Tsuga canadensis decline. Multivariate analysis was then used to investigate the patterns of vegetation change. The results suggest that the Tsuga canadensis decline stimulated the exponential increase in abundance of several taxa and triggered a successional sequence. In addition, it appears that the decline may have influenced long-term vegetation dynamics.

POSTGLACIAL VEGETATION HISTORY
OF THE CANADIAN HIGH ARCTIC

K. Gajewski1, M. Garneau2 and J.G. Bourgeois3

1 University of Ottawa, Department of Geography, Ottawa, Ontario K1N 6N5, Canada
2 Commission géologique du Canada, Division de la science des terrains, Sainte-Foy, Québec G1V 4C7, Canada
3 Geological Survey of Canada, Terrain Sciences Division, Ottawa, Ontario K1A 0E8, Canada

Little is known about the postglacial vegetation history of the Canadian high arctic. This is due in part to a number of technical problems when analyzing pollen assemblages in the polar desert environment. However, there has been considerable research activity during the past several years, and the limitations to the interpretation of pollen diagrams caused by this environment are beginning to be identified.
Pollen assemblages from various pollen traps show the importance of the long-distance transported component of the pollen rain. Analysis of the surface sediments of lakes indicates the relationship of the pollen to the modern vegetation. Several cores spanning the postglacial period show subtle changes in the vegetation.

INTERPRETATION OF HIGH ARCTIC
POLLEN DIAGRAMS

M. Garneau1, J.G. Bourgeois2 and K. Gajewski3

1 Commission géologique du Canada, Division de la science des terrains, Sainte-Foy, Québec G1V 4C7, Canada
2 Geological Survey of Canada, Terrain Sciences Division, Ottawa, Ontario K1A 0E8, Canada
3 University of Ottawa, Department of Geography, Ottawa, Ontario K1N 6N5, Canada

Pollen and plant macrofossils from lake sediments, peats and ice cores are used to interpret past environments of the arctic. Each of these sediment types records environmental changes with a particular spatial and temporal resolution. There are number of special problems associated with high arctic paleoenvironmental analyses. These include contamination of Holocene sediments by fossils derived from pre-Quaternary sediments, significant amounts of long-distance transport, low pollen concentrations, and stratigraphic inversions. Integrated studies, combining analyses from peat deposits, lake sediment and ice cores can potentially identify these problems.

CENOMANIAN - TURONIAN PALEOENVIRONMENTS AND PALYNOLOGICAL ASSEMBLAGES, BARINAS BASIN, SOUTHWESTERN VENEZUELA

Clara Guevara de Guerra

Laboratorio Geológico, Corpoven S.A., Apartado 4326, Puerto La Cruz, Venezuela.

Palynological assemblages associated with different paleoenvironments of deposition within third-order cycles defined during the Cenomanian-Turonian in the Barinas Basin are described.
The UZA-2.3 sequence consists, to the north, of fine to medium grained sandstones and a calcareous interval at the top. To the south, the sandstones are coarse grained and the limestones are represented by calcareous sandstones. Palynological studies reveal an abundance of dinoflagellates such as Canningia senonica, Odontochitina operculata, Florentinia mantellii and Cerodinium boloniense to the north, whereas species of pollen and spores are predominant to the south.
The UZA-2.4 sequence consists of sandstones and shale intercalations to the north, with dinoflagellates species such as Palaeohystrichophora infusorioides, Odontochitina sp., Exochosphaeridium bifidum, Canningia senonica and spores of the genus Cyathidites. To the south this sequence is composed of massive sand bodies and characterized by Oligosphaeridium complex, O. pulcherrimum, Cribroperidinium cooksoniae, Cometodinium? whitei and terrestrial palynomorphs such as Ephedripites sp., Camarazonosporites sp., and Callialasporites sp.
The lower part of UZA-2.5 sequence consists of a calcareous interval where subaerial dissolution took place. The upper part is interpreted as the 91.5 Ma maximum flooding surface in which the anoxic conditions may have inhibited the development of the dinoflagellates. In all UZA-3.1 sequence only dinoflagellates are observed. To the north the most common species are: Dinogymnium sp., Palaeohystrichophora infusorioides, Oligosphaeridium sp., Circulodinium distinctum, Palaeoperidinium cretaceum and Spiniferites sp. To the south the assemblage is constituted by abundant Oligosphaeridium, Hystrichodinium pulchrum, Exochosphaeridium bifidum, Hystrichosphaerina turonica, Areoligera senonensis and Palaeohystrichophora infusorioides. The association identified in this sequence could indicate that chorate dinoflagellates were more characteristic of shallow water marine environments.

PLIOCENE AND LOWER PLEISTOCENE
DINOFLAGELLATES AND ACRITARCHS OF THE NORTH ATLANTIC: TAXONOMY, MAGNETOBIOSTRATIGRAPHY, AND
PALEOCLIMATOLOGY

Martin J. Head and Geoffrey Norris

Department of Geology, University of Toronto, Toronto, Ontario M5S 3B1, Canada

Diverse dinoflagellate and acritarch assemblages from the North Atlantic Pliocene have been examined from several Deep Sea Drilling Project (DSDP) holes targeted for their excellent magnetostratigraphic and biostratigraphic control. Results confirm the applicability of dinoflagellates and acritarchs for high resolution biostratigraphy of the Pliocene. DSDP Hole 603C, situated on the lower continental rise off New Jersey, has an essentially complete sedimentary record of Pliocene and lowermost Pleistocene. DSDP Hole 610A, in the Rockall Trough, eastern Atlantic, has an almost complete section spanning middle lower Pliocene through lower Pleistocene. Ocean Drilling Program Hole 646B in the Labrador Sea offers a third point of comparison.
Biostratigraphically useful events recognized for the lower lower Pliocene include the highest occurrences (HO) of Pyxidinopsis pastilliformis and Cristadinium diminutivum; for the middle lower Pliocene include lowest occurrences of Cyst type 1 and Corrudinium sp. 1, both of de Vernal and Mudie (1989), highest persistent occurrence (HPO) of Reticulatosphaera actinocoronata, and the HO of Cyst type 1 of de Vernal and Mudie (1989); for the upper lower Pliocene include the HPO of Corrudinium sp. 1 of de Vernal and Mudie (1989), and HPO of the Batiacasphaera micropapillata / B. minuta complex. The lower upper Pliocene (Gauss magnetochron) is characterized by the highest occurrences of many taxa which, in holes 603C and 610A, include the HO of Invertocysta tabulata, Selenopemphix dionaeacysta, Edwardsiella sexispinosa, and Barssidinium spp., the highest common occurrence (HCO) of Incertae sedis 1 of de Vernal and Mudie (1989), and the highest persistent occurrences of Operculodinium janduchenei, Operculodinium? eirikianum, and Invertocysta spp. The upper upper Pliocene is marked by the HCO of Cymatiosphaera? invaginata, while the HO of Habibacysta tectata is tentatively identified within the uppermost Pliocene-lower Pleistocene interval.
Dinoflagellate and acritarch ranges are shown to clearly reflect cooling events in the North Atlantic, the most pronounced of these being at ca. 2.6Ma (time scale of Cande and Kent, 1992) where in holes 603C and 610A a number of cool-sensitive species disappear in response to the initiation of North Atlantic glaciation.

UPPER CRETACEOUS DINOFLAGELLATES AND CHRONOSTRATIGRAPHY IN THE SUBSURFACE OF SOUTHWESTERN VENEZUELA

Javier Helenes

C.I.C.E.S.E., Departamento de Geologia, Carretera Tijuana-Ensenada, Ensenada, Baja California 22860, Mexico. Mailing address: P.O. Box 434843, San Diego, California 92413-4843, U.S.A.

Upper Cretaceous strata in the subsurface of southwestern Venezuela unconformably underlie middle Eocene sedimentary rocks and conformably overlie late Albian clastics. Dinoflagellates contained in these strata are the basis for a proposed correlation with Third Order Cycles (Haq et al., 1988). This correlation increases the precision and reliability of local geological models and regional tectonic events.
Analyses of conventional core, sidewall core and cuttings samples revealed several events, including first evolutionary appearances of the dinoflagellate taxa Canningia senonica, Cerodinium sp., Dinogymnium sp., Andalusiella sp. and Senegalinium bicavatum. Events also included the evolutionary extinction of the dinoflagellate taxa Pseudoceratium securigerum, Vesperopsis mayi, Xenascus plotei, and Canningia senonica, as well as the terrestrial palynomorphs Corollina sp. and Ariadnaesporites sp. These results indicate that the Cretaceous in the area represents almost continuous marine sedimentation from late Albian to early Campanian. A major unconformity between early Campanian and possibly late Maastrichtian strata, and another major unconformity between possibly late Maastrichtian and middle Eocene sedimentary rocks.
According to this study, the sequences represented in the column include most cycles from the basal Cenomanian (UZA-2.2) to the early Campanian (UZA-3.4) and possibly also the late Maastrichtian UZA-4.5 Cycle. There is a minor hiatus between Cycles UZA-2.5 and UZA-3.1 and a major hiatus between the early Campanian UZA-3.4 Cycle and the possibly late Maastrichtian UZA-4.5 Cycle.
The Campanian-Maastrichtian unconformity encompasses approximately 12 Ma and probably represents the emplacement of oceanic nappes in western Colombia. The Maastrichtian - Eocene unconformity encompasses approximately 26 Ma and probably represents the emplacement of the Lara Nappes in northern Venezuela.

LATE EOCENE TO EARLY OLIGOCENE BATHYMETRIC AND SEA WATER TEMPERATURE CHANGES IN SOUTHERN MISSISSIPPI AND ALABAMA, U.S. GULF COAST

Carlos A. Jaramillo* and Francisca E. Oboh

Department of Geology and Geophysics, University of Missouri-Rolla, Rolla, Missouri 65401, U.S.A.
* Present address: Department of Geology, University of Florida, Gainesville, Florida 32601, U.S.A.

The transition from the middle Eocene to early Oligocene has been one of the most important events during the Cenozoic. Global temperatures decreased and the diversity of earth's species decreased dramatically. The present study investigated dinoflagellate cyst distribution during the late Eocene-early Oligocene time in four sections located in southern Mississippi and Alabama. This study aimed at identifying changes in the ocean temperatures and proposing a sequence stratigraphic model for this area.
The lithofacies and dinocyst distribution in St. Stephens Quarry and Young #l sections, coupled with the palynofacies assemblages in Young #l, were used for sequence stratigraphic interpretations. Four flooding surfaces have been identified. The first, at the middle of the Shubuta Clay, which is interpreted as a maximum flooding surface (MFS), is coincident with the Eocene-Oligocene boundary. The second flooding surface, at the Forest Hill-Mint Spring boundary, is interpreted as a transgressive surface (TS) and is coincident with a sequence boundary (SB). The third flooding surface, at the middle of the Marianna Limestone, is interpreted as MFS, while the fourth, at the Bucatunna-Chicasawhay boundary, is interpreted as a TS and it is coincident with a SB. It is evident that a thick deltaic sequence occurred in the Young #l area (southeastern Mississippi), whereas interdeltaic shelf-edge deposits prograded more slowly at the St. Stephens Quarry area (southwestern Alabama). Multivariate statistical analyses of the dinocyst distribution yielded seven paleoecological groups, which have been used to recognize two intervals of sea water temperature cooling. The first interval occurred during the earliest Oligocene, while the second occurred during the latest part of the middle early Oligocene.

RECONSTRUCTING PALEOBATHYMETRIC
CURVES FROM PALYNOFACIES ANALYSES OF SILICICLASTICS, CHERTS AND CARBONATE
ROCKS OF NEARSHORE-OUTER SHELF
DEPOSITIONAL SYSTEMS

Carlos A. Jaramillo*, Francisca E. Oboh and Oscar Yepes

Department of Geology and Geophysics, University of Missouri-Rolla, Rolla, Missouri 65401, U.S.A.
* Present address: Department of Geology, University of Florida, Gainesville, Florida 32601, U.S.A.

Palynological studies of detrital organic matter (palynofacies analyses) have increased in importance in sequence stratigraphic interpretations in recent years. Paleobathymetric curves derived from palynofacies data are a good approach for analyzing relative sea level changes, movements of the shoreline, and basin-wide chronostratigraphic correlations. Lithofacies and palynofacies data from six stratigraphic sections from the Cretaceous of Colombia (South America) and the late Paleogene of the U.S. Gulf Coast have been used to reconstruct paleobathymetric curves for these stratigraphic intervals. Detailed lithofacies analyses formed the basic framework for paleoenvironmental interpretations.
Our palynofacies technique consisted of three main steps. First, a minimum of 300 organic matter particles were counted in each sample, and we recorded the composition of each particle, size of longest axis, sorting and level of degradation. Eleven different types of organic matter were recognized: amorphous organic matter, dinoflagellates/foram linings, yellow-brown fragments, black-brown fragments, black debris, resins, sporomorphs, cuticles, plant tissue, wood and fungi. The second step involved the statistical analyses of the recorded data, such as lognormal distribution and cluster analysis. These yielded several groups of samples and organic matter. Under the assumption that allocyclic processes were prevalent, the clustered samples were ordered according to their organic matter content, which indicated their positions relative to the paleoshoreline. The groups of organic particles produced by the cluster analysis are plotted alongside the stratigraphic section, as well as the mean size of each organic matter particle. When present, ecologically valuable dinoflagellate or pollen associations were also plotted. The last step consisted of constructing the relative paleobathymetric curves based on the palynofacies and lithofacies data. These curves have been compared with those produced by other techniques.

POLLEN CONTAMINATION OF CITRUS NECTAR

Gretchen D. Jones and James R. Coppedge

USDA, AWPMRU, 2771 F&B Rd., College Station, Texas 77845, U.S.A.

Adults of numerous insect species feed on nectar and other plant exudates that are frequently associated with flowers. As a result of this feeding activity, these adults become internally and externally contaminated with pollen. Identification of this pollen is useful in the study of insect feeding resources and movement.
Citrus spp., Quercus spp., Salix spp., Guara spp., and Pithecellobium spp. have been identified as foraging sources for Helicoverpa zea (Boddie) (corn earworm) adults. Blooms from these taxa secrete volatiles that are highly attractive to feeding corn earworm and other noctuid adults. However, the volatiles from blooms of other taxa found on corn earworm adults do not produce a positive foraging response. Pollen from negative foraging response nectars may be contaminants in the positive foraging response nectars.
Pollen falls into the nectar when the flower's anthers are dislodged by the wind, insects, animals, etc. Once the nectar is contaminated with pollen, that pollen will be taken into the insect's digestive system or may "stick" to the proboscis when the insect is foraging. Other pollen types may also occur in a taxon's nectar due to anemophilous grains or cross-contamination by insects when foraging.
We examined the amount and type of pollen within Citrus nectar. Our study examined the nectars of two varieties of Citrus, rio red grapefruit and mars orange. Nectar from rio red grapefruit was more contaminated with pollen than mars orange. Rio red grapefruit also was more contaminated with other pollen types. In addition, daytime pollinators contaminated the nectar with pollen more than night time pollinators.

DINNER WITH THE BOLL WEEVILS

Gretchen D. Jones and James R. Coppedge

USDA, AWPMRU, 2771 F&B Rd., College Station, Texas 77845, U.S.A.

The boll weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae) invaded Texas over 100 years ago and has spread to all cotton growing areas in the United States. Until recently, scientists thought that the boll weevil only foraged and reproduced on Gossypium hirsutum Linnaeus (cotton). This year the boll weevil eradication program has become a nation-wide program to eradicate the boll weevil from the cotton producing areas of the United States. Cotton fields across parts of the nation will be sprayed for boll weevils according to how many weevils are captured in traps at the edges of cotton fields. It is anticipated that this ongoing program will eradicate the boll weevil from all cotton producing areas in the United States.
One of the premises of this program is that boll weevils will quickly starve if they emerge from overwintering habitats before cotton is fruiting. This is frequently called suicidal emergence. Previous research has provided limited evidence that boll weevils can survive on pollen from sources other than cotton, however, these findings have been largely ignored. Preliminary results from our laboratory indicate not only that boll weevils can survive by feeding on pollen of plants other than cotton, but also that this foraging is probably an important mechanism for the long term survival of these pests.
To get a better determination of their foraging resources, both external and internal pollen analyses were conducted. A typical boll weevil menu for April around College Station, Texas consisted of:
main course: Quercus spp., oaks,
Salix nigra H. Marshall, black willow
vegetables: Fabaceae, bean family
Brassicaceae, mustard family
Geranium sp., crane's bill
fruits: Prunus spp., plums
Pyrus sp., pear
Crataegus sp., hawthorn
Morus rubra Linnaeus, red mulberry
dessert: Carya illinoinensis (F. von Wangenheim) K. Koch, pecan
To prevent digestive problems, the boll weevils consumed Zanthoxylum clava-herculis Linnaeus, toothache tree, and Poaceae, grasses.
In the month of May, the diet changed to fewer oaks and fruits, but more grasses, and the addition of a salad consisting of dandelion type Asteraceae. For dessert they had Ambrosia sp. and Platanus sp.

POLLEN STUDIES RECOVERED FROM PERSIAN PERIOD (6-4th CENTURIES B.C.) AMPHORAS IN A SHIPWRECK AT TANTURA LAGOON, ISRAEL

John G. Jones1, Vaughn M. Bryant, Jr.2, and Eri Weinstein2

1 Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Panama
2 Palynology Laboratory, Texas A&M University, College Station, Texas 77843-4352, U.S.A.

Our preliminary pollen analysis of sediments, resins, and pitch samples recovered from the inside of amphora vessels found in a sunken Persian Period shipwreck (6-4th centuries B.C.) are providing useful clues as to the contents of the ship's cargo. The site, located in Tantura Lagoon, approximately 25 km south of Haifa, Israel, was first discovered during an underwater survey of the lagoon in 1983. However, efforts to excavate the site did not begin until 1994, and excavations are still ongoing.
Our study demonstrates that pollen analyses are possible from these types of samples, and that additional types of fossil pollen studies should be continued for both this and other shipwreck sites. Initial findings from the amphoras reveal that part of the sunken ship's cargo consisted of foods and other agricultural products. Based mainly on fossil pollen, and in some cases a few recovered seeds, we are able to identify the following economic goods as being probable cargo goods: 1) olives or olive oil; 2) grapes, raisins, or grape wine; 3) terebenth resin; 4) pine pitch; 5) various types of spices; 6) sumac; 7) cereal grains; and 8) possibly dates and plums.
Non-economic pollen types (pine, fir, oak, hickory, willow, grass, composite, etc.) found during this study offer a few clues that might provide a key to determining the ship's home port, or other ports where it loaded or unloaded cargos. Nevertheless, the majority of the fossil pollen recovered from the shipwreck site reflects economic products that were undoubtedly being carried as part of the ship's cargo at the time it sank.

MIOSPORES AND CONODONTS FROM THE DEVONIAN STRATA OF THE WESTERN PART OF THE MICHIGAN BASIN

Curtis R. Klug

Department of Geology, University of Iowa, Iowa City, Iowa 52242, U.S.A.

The westernmost extent of Devonian strata of the Michigan Basin is represented by a narrow north-south trending belt in southeastern Wisconsin. Recent construction of deep sewer tunnels in Milwaukee has made available cores through most of the Devonian section. Devonian strata in Wisconsin have been assigned to four formations. These are, in ascending order, the Lake Church, Thiensville, Milwaukee, and Antrim formations. The Antrim does not occur in surface outcrop, nor was it present in the available cores, and will not be considered herein. Dolostone is the dominant lithology of the lower three formations, although shales and argillaceous dolostones are common in the upper part. Interpreted depositional environments range from open marine to restricted peritidal. Samples from the cores, as well as from surface exposures, have been simultaneously processed for miospores and conodonts. Conodonts have been recovered from much of the section, and suggest a range in age from late Eifelian (kockelianus Zone) to late Givetian or possibly earliest Frasnian (norrisi Zone). Although miospores are present throughout the section, this is the first report of their occurrence in the Wisconsin Devonian. The miospores tend to be abundant, diverse, and well-preserved, and occur both in direct association with conodonts and in strata barren of conodonts. In general, the miospore floras appear to agree with the conodont-based age determinations. A possible exception to this is in the Thiensville Formation where a limited conodont fauna suggests an age no older than Givetian. Miospores from these samples, however, suggest that these strata may be Eifelian in age. Many of the miospore taxa appear to be endemic to the Midcontinent Region of North America. For example, some forms, such as Dibrochosporites nodosus, encountered in the Thiensville and Lake Church formations, have elsewhere only been reported from the Wapsipinicon Group of Iowa and Illinois. Although these forms may be of limited biostratigraphic value outside of this area, some appear to have potential biostratigraphic utility within the Midcontinent region.

CAN A PALYNOLOGICAL ANALYSIS BE USED TO DETERMINE IF STOMACH CONTENTS OF A HADROSAUR FROM THE DINOSAUR PARK
FORMATION (CAMPANIAN, UPPER CRETACEOUS)
OF ALBERTA, CANADA, IS THE DINOSAURS LAST MEAL OR NOT ??

E.B. Koppelhus1, P.J. Currie2, and A. Fazal Muhammad3

1 Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark
2 Royal Tyrrell Museum of Palaeontology. Box 7500, Drumheller, Alberta T03 0Y0, Canada
3 Mount Royal College, Calgary, Alberta T3E 6K6, Canada

A duckbilled dinosaur (Corytlhosaurus casuarius) found in Dinosaur Provincial Park had the thoracic region almost entirely covered by skin impressions. It was noticed that the sandstone within the body cavity contained abundant remains of small pieces of twigs and branches, whereas the sandstone external to the skin impressions lacked any significant evidence of plant fossils.
Because it seemed possible that the plant remains in the body cavity might represent "stomach" contents, the specimen was excavated. To determine whether the fossils might represent food ingested by the hadrosaur, plant remains, including palynomorphs, found within the body cavity, were examined microscopically.
The palynomorph assemblage found in the stomach include more than thirty species of miospores, megaspores, dinoflagellate cysts and fungal spores. The palynomorphs are well preserved and the most abundant are bisaccate gymnosperm pollen. Angiosperm pollen are common and pteridophyte spores are less common. The palynomorphs Proteacidites, Aquilapollenites and Mancicorpus have restricted biostratigraphic ranges. The dinoflagellate cysts found were reworked from the Early Cretaceous.
Most of the plant remains are in the form of woody fragments ranging from 1.0 to 4.0 cm in length and 0.2 to 1.5 cm in width. Seed and seed pods seem to be relatively common. Finally, small pieces of charcoal were also found.
The composition of the palynomorph assemblage, the reworked dinoflagellates and the plant remains suggest that the stomach contents were introduced by fluvial action.

PALYNOSTRATlGRAPHY OF THE SORTEHAT
FORMATION, JAMESON LAND, EAST GREENLAND

Eva Bundgaard Koppelhus1 and Carina Fabricius Hansen2

1 Geological Survey of Denmark and Greenland, Østcr Voldgade 10, DK-1350 Copenhagen K, Denmark
2 Geological Institute, University of Copenhagen, Øster Voldgadc 10, DK-1350 Copenhagen K, Denmark

The Sortehat Formation is exposed in the Jameson Land Basin, in the southernmost part of the north-south trending fault-bounded Mesozoic rift system of East Greenland. The formation consist of restricted to fully marine black offshore shales and is in sharp sedimentological contrast to the underlying sandy shallow marine deposits of the Neill Klinter Formation and the overlying sandy fully and shallow marine Pelion Member of the Vardekløft Formation. The Sortehat Formation is 60-10 m thick with sharp upper and lower boundaries which can be traced laterally for over 100 km.
The Sortehat Formation has not been precisely dated before, but the underlying Neill Klinter Formation (Ostreaelv Member) has been dated to late Toarcian to early Aalenian age on the basis of ammonites and belemnites. The base of the overlying Vardekløft Formation (Pelion Member) has been dated to Early Boreal Bajocian age, based on ammonites.
Detailed palynological and sedimentological studies have been carried out on the Sortehat Formation. Three palynological assemblage zones have been recognized in the formation at three different localities, including the type locality, Sortehat. Approximately 110 species of palynomorphs have been identified: 45 spore, 30 pollen, 22 dinoflagellate cyst, 10 acritarch, 2 algal and some fungal spore species. Based on this palynological investigation the age of the Sortehat Formation is suggested to be Aalenian to ?early Bajocian because of the composition of palynomorphs. The assemblages are subdivided into the Botryococcus, Nanno-ceratopsis gracilis and the Sentusidinium pelionense zones.

MAJOR FLORAL BREAKS IN LATE CRETACEOUS - QUATERNARY DINOFLAGELLATE CYST ASSEMBLAGES IN NORTHERN JAPAN

Hiroshi Kurita1 and Kazumi Matsuoka2

1 JAPEX Research Center, Japan Petroleum Exploration Co., Ltd., 1-2-1, Hamada, Mihama, Chiba, Japan 261
2 Department of Geology, Faculty of Liberal Arts, Nagasaki University, 1-14, Bunkyo, Nagasaki, Japan 852

Compilation of biostratigraphic studies on Late Cretaceous-Cenozoic dinoflagellate cyst assemblages in northern Japan has revealed several major floral breaks expressed as discontinuities in diversity (number of genera/species) trend and/or in species composition. These changes may be the result of paleoenvironmental events on either a local or a regional scale. The database was obtained from outcrop sections encompassing Upper Albian to Quaternary marine records at various localities in northern Honshu and Hokkaido. The ages of the sections studied were calibrated precisely against other evidence including planktic foraminifers, diatoms, calcareous nannofossils and molluscs.
Distinctive high diversity occurs in five intervals; the upper Albian-Cenomanian, Santonian, upper Paleocene, upper lower-lower middle Miocene, and Pliocene-lower Pleistocene. Each interval is generally followed by a sharp, significant drop in diversity together with considerable change in species composition. The less diverse assemblages between the intervals of diverse assemblages are sometimes remarkably limited in species composition. In particular, dominance of few genera/species distinguishes the Turonian and Eocene - early Oligocene assemblages. This dominance suggests such paleoenvironmental stresses as isolation or stagnation of water masses.

UPPER CRETACEOUS DINOFLAGELLATE CYST BIOSTRATIGRAPHY ALONG A SURFACE SECTION
IN NORTHERN JAPAN

Hiroshi Kurita and Akiko Obuse

JAPEX Research Center, Japan Petroleum Exploration Co., Ltd., 1-2-1, Hamada, Mihama, Chiba, Japan 261

A brief description of Late Cretaceous dinoflagellate cyst assemblages from a composite section in northern Hokkaido, northern Japan, is presented and their biostratigraphic implications are discussed.
Outcrop sections of the Yezo Supergroup in the Kotanbetsu and Sarufutsu areas comprise a single composite section, which represents the upper Albian to Maastrichtian. The age of the section is determined with earlier data on molluscs and foraminifers. Sedimentary facies analysis indicates that most of the upper Albian to Santonian part was deposited under shelf paleoenvironments with minor intervals of fluvial sedimentation, while the Campanian-Maastrichtian part is rich in coarse-grained clastics and interpreted as being mostly deltaic.
The upper Albian-Maastrichtian outcrop section yielded a number of dinoflagellate cyst species, most of which are identifiable with taxa established elsewhere including the North Atlantic region. In the assemblages there are distinct stratigraphic changes at several levels, which may serve as potential biostratigraphic markers. Apparent maximum diversity was observed in the upper Albian-Cenomanian and Santonian.
Assemblages from the upper Albian-Cenomanian are generally diverse and include various types of cysts, some of which may range down well into the Lower Cretaceous. Significant discontinuity in species composition was observed at the Cenomanian-Turonian boundary. Relatively low diversity and frequent occurrence of peridinioid taxa mark the Turonian-
Coniacian assemblages. The Turonian assemblages, in particular, are noticeable for consistent dominance of morphologically similar species of Isabelidinium. The Santonian assemblages represent another culmination in species diversity. Frequent dominance of peridinioid species was observed in the Campanian-Maastrichtian assemblages, which are generally less diverse. This was probably influenced by the nearshore paleoenvironments.

CHALLENGES AND OPPORTUNITIES IN QUATERNARY PALYNOLOGY: EXAMPLES FROM THE CANADIAN BOREAL FOREST

Glen M. MacDonald*

Department of Geography, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
* Current address: Department of Geography, Bunche Hall, University of California at Los Angeles, 405 Hilgard Ave., Los Angeles, California 90095-1524, U.S.A.

Palynology, like most scientific disciplines, is facing considerable challenges. Decreases in government funding for research agencies such as the Geological Survey of Canada and the United States Geological Survey are coupled with corporate downsizing and a reduction of professional palynologists in industry. Academic palynologists are facing decreased infrastructure support and career opportunities as universities grapple with the impacts of federal, provincial or state deficits. Federal funding of university research is under pressure through cuts such as those to the NSERC in Canada and NOAA in the United States. In terms of research, tasks such as producing the first stratigraphic description of a particular unit, or providing the first postglacial vegetation reconstruction of a certain region have generally been completed. Funding for further descriptive research is unlikely. Despite these many challenges, we are in a period of exceptional opportunities for Quaternary palynologists. These opportunities are driven by the three factors outlined below.
First, biologists, climatologists, hydrologists etc. realize that the span of historical records pertaining to phenomena such as climate change, vegetation processes or drought occurrence are often far too short to portray the natural variability in these systems. Palynological data of the Holocene are increasingly seen as one avenue to extend historical records back millennia. An example of this research is a high resolution reconstruction of fire occurrence and subsequent vegetation change in Wood Buffalo National Park, Alberta. A 1,000 year pollen record from varved lake sediments provides clear indications of repeated burning and the successional response of the vegetation surrounding the lake.
Second, intense interest in the potential impact of greenhouse warming has led to scrutiny of Holocene palynological records of past periods of greater warmth. Conditions during such past warming periods may provide insights into the reaction of the atmosphere and biosphere to future greenhouse warming. Reconstructions of the northward expansions of spruce and pine in western Canada at the beginning of the Holocene have been made using a network of fossil pollen sites. Such reconstructions can provide insights into the behaviour of trees in response to future warming.
Third, as research techniques have become more sophisticated, and science funding has decreased, scientists are finding a 'team' approach to be the most advantageous way to undertake research. Palynologists generally have solid backgrounds in both biology and the earth sciences. Many palynologists are also knowledgable in archaeology. The multidisciplinary background of palynologists make them particularly capable of participating in, and leading, such research teams. The environmental inferences that can be drawn from multidisciplinary research are often much more secure and detailed than could be obtained by any one researcher. An example of such a multidisciplinary project is PACT (Palaeoecological Analysis of the Circumpolar Treeline). PACT combines pollen, stomate, macrofossil, diatom, chrysophyte, chironomid, isotope analyses and several other techniques to reconstruct northern treeline history in Canada and Russia.

LATE DEGLACIATION BY DOWNWASTING ICE, NORTHEAST AVALON PENINSULA, NEWFOUNDLAND, CANADA: AN APPLICATION OF THE EARLY POST-GLACIAL POLLEN RECORD

Joyce Brown Macpherson

Department of Geography, Memorial University of
Newfoundland, St.John's, Newfoundland A1B 3Z6, Canada

Basal radiocarbon dates from lake sites on the northeastern Avalon Peninsula, Newfoundland, suggest that final deglaciation began at most a few centuries before 10 ka BP on the interior plateau and proceeded by downwasting. Similar but diachronous pollen sequences at key sites indicate that pioneer herb and dwarf shrub stages gave way within 400 years to shrub-birch heath into which spruce migrated regionally at about 8.5 ka BP. The pioneer herb PAZ is preceded by a mixed herb-shrub PAZ with Artemisia by comparison with the sequence of vegetation from the Storbreen glacier foreland, Norway, studied by the Jotunheimen Research Expeditions (Matthews, 1978), it is shown that the initial mixed PAZ could result from the existence of terrains of different ages within each catchment at the time when lake sediment accumulation began, supporting the radiocarbon evidence for downwasting ice.

THE EOCENE OFFSHORE MID-NORWAY, DINOCYSTSTRATIGRAPHY AND GEOCHRONOLOGY

G. Mangerud and I.L. Kristiansen

Norsk Hydro Research Centre, P.O. Box 4313, N5028 Bergen, Norway

As part of a palynostratigraphic study comprising the whole Tertiary succession of offshore Norway, the Eocene dinocyst stratigraphy of offshore mid-Norway will be presented. During the Eocene the western parts of this area was characterized by continental separation starting in the latest Paleocene - earliest Eocene (anomaly 24). In eastern areas a rather wide shelf trapped sediments basically sourced from the Baltic Shield. A westwards progradation, along with relatively fast subsiding basins further out on this passive margin, resulted in a thick Eocene succession now assigned to the Brygge Formation.
A number of wells drilled in this succession is analyzed for palynomorphs and a detailed dinocyst stratigraphy for Mid-Norway is established. Well 6406/11-1S on the Halten Terrace and wells 6306/12-1 and 12-2 in the Møre Basin are selected to demonstrate both the quantitative and qualitative dinocyst composition. The main focus in this presentation will be a review of stratigraphically important dinocyst species, and their relationship to geochronological units. This includes two Priabonian events, four Bartonian events, eight Lutetian events and eight Ypresian events. Comparisons with published zonations from the North Sea will be discussed.

THE LITTLE ICE AGE IN NORTHWESTERN BRITISH COLUMBIA: EVIDENCE FROM PONDS, PEATS AND POLLEN

Rolf W. Mathewes

Department of Biological Sciences and Institute for Quaternary Research, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada

Paleoecological investigations were conducted in the northern Coast Ranges of British Columbia as part of an integrated study of late Holocene fluctuations of glaciers and ice-dammed lakes. Cores collected from a small lake (Spillway Pond) in the glacier foreland of Berendon Glacier and pits dug in a nearby wetland (Berendon Fen) record Little Ice Age and earlier Neoglacial advances and retreats. Glacier advances are identified by layers of mineral sediment, derived either by inundation due to higher lake levels, or by lake overflow via spillways.
Pollen and plant macrofossil analyses were used to interpret the local paleoenvironments. At Spillway Pond, the beginning of the Little Ice Age is represented by pollen assemblages rich in shrub alder (Alnus viridis), heaths (Ericales), and a variety of herbs, including Artemisia, Caltha and Valeriana sitchensis. Tree pollen is at a minimum during this interval. The end of the Little Ice Age is marked by an abrupt increase in percentages of tree pollen, primarily mountain hemlock (Tsuga mertensiana), coupled with a corresponding decrease in non-arboreal pollen. At Berendon Fen, a thick clastic sediment layer was deposited on top of peat between 10.5-19 cm. Very high (approximately 50%) values of fern spores at the base of this sediment suggest erosion of soils by overland flow of lake waters spilled during a late high stand of Summit Lake.
Chronology of Little Ice Age and earlier events is based on 18 new and 11 previously published 14C ages. Supplemented by dendrochronological data from a moraine surface, the Little Ice Age began more than 500 years ago and peaked in the early to middle seventeenth century (ca. 1600-1650AD). This age is around 100 years earlier than peak glacier advances in southern Alaska, but corresponds to periods of cooling and end-moraine formation in the Canadian Rocky Mountains, and with European alpine glaciation.
Environmental changes in northwestern B.C. since the end of the Little Ice Age have also been dramatic. Glacier recession continues, a large ice-dammed lake has drained completely, and tree pollen has increased significantly in recent peats and lake sediment. A thin layer of organic-rich sediment (0-4 cm) indicates increased productivity in Spillway Pond following the Little Ice Age, probably due to warming and increased length of growing season up to the present.

POLLEN ANALYSIS ON GRENADA, WEST INDIES

J.H. McAndrews

Department of Botany, Royal Ontario Museum and
Departments of Botany and Geology, University of
Toronto, Toronto, Ontario M5S 2C6, Canada

This tropical, high, oceanic island of volcanic origin harbours remnant stands of rain forest, dry seasonal deciduous forest and mangrove forest. We have collected most of the flora of 800 species and made pollen reference slides. Pollen analysis and radiocarbon dating of sediment cores from volcanic basins provides information on Quaternary vegetation, climate, sea level and human history. Lake Grand Etang, a maar lake surrounded by rain forest at 500 m asl, yielded a 12 m long sediment core with five radiocarbon dates, indicating continuous sedimentation back to 25,000 BP; abundant fern spores indicate a continuous history of rain forest. Lake Antoine, also a maar but in seasonal forest just above modern sea level, yielded an 8 m long core which dates back to 10,000 BP. Levera Pond and surrounding mangrove swamp at modern sea level occupies a collapse basin; three dated cores indicate it was a bay of the sea until 2,300 years BP when a barrier bar isolated the pond and allowed swamp to form. In the 18th and 19th centuries, erosion from sugar cane farming increased sedimentation.

PALYNOMORPHS AS TRACERS OF TURBIDITES AND ICE RAFTING: LABRADOR SEA, MID ATLANTIC RIDGE AND IBERIA ABYSSAL PLAIN

Francine M.G. McCarthy1 and Peta J. Mudie2

1 Department of Earth Sciences, Brock University, St. Catharines, Ontario L2S 3A1, Canada
2 Geological Survey of Canada (Atlantic), Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada

The processes involved in transporting pollen and spores to deep sea sediments are complex. Because of this taphonomic complexity, it is difficult to reconstruct paleoenvironments and paleoclimates from the marine assemblages in the traditional palynological sense. This complexity can, however, be used to infer depositional processes, e.g. to distinguish pelagic sediments from turbidites and ice rafted sediments.
Variations in influx of terrestrial palynomorphs to the deep sea are primarily a function of the vegetation on adjacent landmasses, and variations in 1) sea level (proximity of the shoreline), 2) atmospheric and oceanic circulation, and 3) fluvial discharge. All of these parameters are variable and are affected by climate change, but pollen influx usually decreases with distance from land; hence, the ratio of marine (dinocysts): terrestrial palynomorphs (pollen and spores), or D:P, increases offshore. Although this trend may change with dinoflagellate productivity, D:P ratios have long been used as a proxy of paleoshorelines.
Contrary to the expected trend, low D:P values (i.e. D:P 1) were found in ~35% of the upper Pliocene-Quaternary samples from ODP Sites 646 (Labrador Sea, 58š12.6'N, 48š22.15'W, 3450 m water depth) and 898 (Iberia Abyssal Plain, 41š41.10'N, 12š07.38' W, 5279 m), and also in ~5-20% of samples from DSDP Sites 607 (41š00.07'N, 32š57.44'W, 3427 m) and 611 (52š50.47'N, 30š18.58'W, 3202.6 m) on the Mid-Atlantic Ridge. We found strong correlation between these low D:P ratios and the occurrence of distal turbidites at ODP sites 646 and 898; here, pelagic sediments have high D:P ratios. Samples with low D:P ratios also tend to contain diverse pollen assemblages, compared to samples with high D:P ratios which are dominated by Pinus. Although it seems obvious that sediments redeposited from more proximal sites should contain anomalously large amounts and diverse assemblages of pollen, to our knowledge no quantitative study has yet been done that uses palynomorphs for distinguishing turbidites from pelagic sediments.
Deposition of large amounts of pollen and spores on the flanks of the Mid-Atlantic Ridge beyond the reach of turbidites may be the result of ice rafting. The much lower percentage of samples with low D:P values at subtropical Site 607 is consistent with this idea since it is south of the Pleistocene iceberg limit. The D:P ratio alone usually does not distinguish turbidites from ice rafted sediments, but ice rafted sediments often contain a high percentage of Paleogene and older palynomorphs reworked from glaciated bedrock.

STOMATE ANALYSIS: AN IMPROVED TECHNIQUE TO DELINEATE PAST SHIFTS IN TREELINE POSITION

Katrina Moser1, Glen M. MacDonald1, Barbara C. S.
Hansen2, Susan Clayden3 and Les C. Cwynar3

1 Department of Geography, McMaster University, Hamilton, Ontario L8S 4K1, Canada
2 Limnological Research Center, University of Minnesota, Minneapolis, Minnesota, U.S.A.
3 Department of Biology, University of New Brunswick, Fredericton, New Brunswick E3B 6E1, Canada

The location of treeline is largely controlled by climate and it is expected that future climate warming will significantly impact this boundary. It is, therefore, important to understand how treeline has responded to past climatic change, especially the rate and magnitude of any changes in vegetation. Paleoecological methods, especially pollen and stomate analyses, provide a means to study such changes. Long distance transport of tree pollen, however, can decrease the resolution of the exact position of treeline in palynological records. Fossil stomate analysis provides one avenue of improving the spatial and temporal resolution of past treeline reconstructions from palynological records.
In order to interpret fossil pollen records it is necessary to understand how present vegetation is represented by modern pollen deposited in lake sediments. Studies of modern pollen, from central Canadian lake sediments, demonstrate that Picea pollen percentages are only greater than 25% when they are from forest/tundra and forest sites. Therefore, fossil samples containing more than 25% Picea pollen are representative of periods when treeline was north of that site. Using this information, it was determined from fossil pollen analyses that treeline existed north of its modern day position between 5,000 BP and 4,000 BP in central Canada, which is corroborated by fossil diatom and geochemical analyses. However, modern pollen analyses also demonstrate that it is possible for a sample with less than 10% Picea pollen to represent a closed forest site, implying that estimates of the timing and magnitude of past forest development from fossil pollen records may be underestimated. Furthermore, some treeline species, such as Larix, are poorly represented in modern lakes sediments.
Macrofossil studies of lake-sediment cores have been used to enhance our understanding of treeline events, but in cases where macrofossils are not found (for example, central Canada) the guard cells of conifer stomata may provide a useful alternative. This study demonstrates that conifer stomata from lake sediment cores provide an improved technique for distinguishing past forest and forest/tundra sites from tundra sites. Stomate analysis, thus, offers a means to more exactly determine the extent and rate of treeline shifts. As well, the stomate record clearly indicates the presence of conifer species poorly represented by the pollen record, such as Larix. This may be particularly important in studies of Larix dominated treeline such as occurs in central and eastern Siberia.

COPEPOD REMAINS IN PALYNOLOGICAL
PREPARATIONS FROM DSDP SITE 502 (LEG 68,
COLOMBIA BASIN, WESTERN CARIBBEAN SEA)

Florin-Alexandru Neumann and Geoffrey Norris

Department of Geology, University of Toronto, Toronto, Ontario M5S 3B1, Canada

Previously unidentified organic microfossils commonly occurring in palynological preparations from upper Miocene to Pliocene deposits penetrated at DSDP Site 502 are shown to consist mainly of copepod remains. Most of them have been identified as segments of exopodites of swimming feet of calanoid copepods. The morphotypes described herein are closely comparable to copepod remains reported by Van Waveren (1993) from Quaternary sediments of the Banda Sea, Indonesia.
We speculate that the preservation of chitin, which usually has low preservation potential, was enhanced at Site 502 by hypoxic to anoxic conditions, which had an inhibitory effect on the activity of aerobic chitinoclastic bacteria.
However, copepod remains are absent from oxidized samples from the same section, which indicates that they may be preferentially removed by oxidation, and that they may be more common than previously thought.

A LATE CAMPANIAN MICROFLORA FROM THE KANGUK FORMATION ON BANKS ISLAND, NWT, CANADA

Florin-Alexandru Neumann and Geoffrey Norris

Department of Geology, University of Toronto, Toronto, Ontario M5S 3B1, Canada

The Upper Cretaceous Kanguk Formation is a lithologically uniform unit extending throughout most of the Canadian arctic islands, representing the last episode of thermal subsidence prior to the onset of the Eurekan Orogeny. In most sections it is represented by a basal black bituminous shale unit overlain by a succession of silty shale and interbedded sandstone. On Banks Island it rests unconformably on Lower Cretaceous deposits, and it is overlain by the Cenozoic Eureka Sound Group or younger rocks.
Macrofossils are scarce in the Kanguk Formation, but outcrop and subcrop microfaunal (chiefly arenaceous foraminifera) and microfloral studies have indicated an age range of ?Turonian to late Campanian/early Maastrichtian on Banks Island. However, some preliminary fission-track investigations, and some recent sequence-stratigraphic correlations, have suggested for these strata a younger age, latest Maastrichtian or early Tertiary.
Moderately diverse assemblages of terrestrial and marine palynomorphs were recovered from samples collected from a 26 m section through the upper unit of the Kanguk Formation at Duck Hawk Bluff (southwestern tip of Banks Island), which included two tephra beds used for fission-track dating. The terrestrial component was dominant: bryophyte and pteridophyte spores, gymnospermous pollen, and triprojectate pollen (Expressipollis sibiricus, E. accuratus, Aquilapollenites quadrilobus) averaged 74% of the assemblages. Laciniadinium arcticum, Spinidinium uncinatum, Circulodinium distinctum, Saeptodinium eurypylum, and Palaeoperidinium pyrophorum were the most common phytoplankton taxa; of the larger species of Chatangiella, only C. ditissima was encountered. The overall composition of the assemblages remained fairly constant throughout the section, suggesting a restricted, near-shore environment.
The assemblages are comparable to zone CVIa-b (Banks Island) of Doerenkamp et al. (1976), and to division H2 (Anderson Basin) of McIntyre (1974), and are older than the Wodehouseia-Kurtzipites datum of Nichols and Sweet (1993), which in the Western Interior Basin approximates the Campanian-Maastrichtian boundary; therefore an age of late Campanian was assigned to the Duck Hawk Bluff section. The 5­10 Ma discrepancy with the results of the fission-track dating is explained by the preliminary nature of the latter.

THE ROLE OF PALYNOLOGY IN PALEOECOLOGICAL ANALYSES OF TERTIARY COALS

Douglas J. Nichols

U.S. Geological Survey, MS 919, Box 25046, Denver, Colorado 80225, U.S.A.

Pollen and spores are important constituents of Tertiary coal, both as petrographic components (the maceral sporinite) and as distinctive indicators of the nature of the depositional environment in which the coal-forming peat accumulated. Palynological analyses, which have been conducted on Tertiary coals since the 1930s, play an increasingly important role in modern, interdisciplinary coal studies.
Among the most important factors controlling the petrographic composition and facies characteristics of coal beds are the kinds and relative abundances of plants that composed the peat. Modern wetland environments in which peat accumulates (mires) range from marshes and bogs to forested swamps; each is inhabited by distinctive plant communities. Plant communities of mires in the Tertiary were also highly diverse and specialized (especially as compared with those of the Carboniferous). Coniferous gymnosperms were the dominant species in some Paleocene mire floras but, continuing a trend begun in Late Cretaceous time, angiosperms became increasingly prominent through the Tertiary. The diverse angiosperm-dominated mire floras produced coals that vary significantly in facies. Such contrasts are evident in contemporaneous coals from different paleolatitudes, as well as among coals of different ages within the Tertiary. Plant communities of mires were associated with varied conditions of climate, water depth, chemistry, and nutrient supply, and the floras can be indicative of these conditions. Pollen and spores present in coal reflect the floristic composition of those plant communities, and thus detailed palynological analyses are critical in paleoecological interpretations. Comprehensive paleoecological analyses of Tertiary coals utilize coal petrography in conjunction with palynology.

PALYNOLOGY OF PALEOGENE LACUSTRINE SHALE AT FLORISSANT FOSSIL BEDS NATIONAL
MONUMENT, COLORADO

D.J. Nichols1, and F.H. Wingate2

1 U.S. Geological Survey, MS 919, Box 25046, Denver, Colorado 80225, U.S.A.
2 Wingate Consulting, 3052 South Ivan Way, Denver, Colorado 80227, U.S.A.

Samples collected through an interval of lacustrine shale interbedded with mudstone and air-fall tuff at Florissant Fossil Beds National Monument yielded rich assemblages of pollen, spores, and algal cysts. Samples are from unit Tf2 of Evanoff, which overlies the unit containing the well-known petrified stumps. Unit Tf2 also yields a wide variety of well-preserved fossil leaves and insects for which the monument is famous. The palynoflora of about 130 species represents vegetation of a lake and regional habitats of latest Eocene age.
Assemblages from most samples are dominated by pollen of gymnosperms, primarily Pinaceae and Taxodiaceae. Angiosperm pollen is diverse (about 100 species), although many species are low in abundance. The numerically most abundant angiosperm pollen species are referable to the anemophilous families Ulmaceae, Juglandaceae, and Fagaceae. Pollen of lake-margin and aquatic angiosperms includes probable representatives of the families Cyperaceae, Nymphaeaceae, Pandanaceae, and Sparganiaceae or Typhaceae; cysts and coenobia of aquatic algae are common. Drier habitats are indicated by consistent presence of pollen of Ephedraceae and Chenopodiaceae/Amaranthaceae. Other species apparently are the stratigraphically oldest records in North America of the Asteraceae, Malvaceae, and possibly the Polemoniaceae. The palynoflora shows little or no response of vegetation to frequent, minor, volcanic ash falls, but a major fluctuation in relative abundances within the Tf2 interval is inferred to reflect the response of vegetation to a major volcanic eruptive event.

UPPER CRETACEOUS DINOFLAGELLATE CYST STRATIGRAPHY, ONSHORE WEST GREENLAND

Henrik Nøhr-Hansen

Geological Survey of Denmark and Greenland. Øster Voldgade 10, DK-1350 Copenhagen K, Denmark

Stratigraphical ranges and geographical distribution of dinoflagellate cysts and selected pollen species are described based on the analysis of 250 samples from 29 surface and 12 subsurface sections of Late Cretaceous age from Svartenhuk Halvø and Nuussuaq peninsula, West Greenland. The sections make up an approximately 1500 m thick black mudstone succession, previously dated as late Turonian to Maastrichtian on the basis of scattered ammonite occurrences.
The dinoflagellate cysts and pollen indicate that the majority of the studied samples are Coniacian/Santonian to Maastrichtian. A few samples have been dated as early Paleocene. It is possible to divide the Upper Cretaceous strata into 10 intervals based on the palynomorph assemblages.
Diversity of dinoflagellate cysts is relatively high in the Coniacian to early Santonian deposits at Svartenhuk Halvø, whereas it decreases in the younger Campanian and Maastrichtian strata of Nuussuaq. The Coniacian to early Santonian assemblages are dominated by the genera Chatangiella and Isabelidinium, which in several samples constitute 20 to 50 percent of the dinoflagellate content.
New finds of ammonites and study of the palynomorphs indicate that the CretaceousTertiary boundary should be moved from the base of what was previously called the 'basal Danian conglomerate' at Annertuneq to approximately 118 m above the top of this conglomerate.
Three new species of the genera Alterbidinium?, Chatangiella and Isabelidinium will be described from this assemblage.

PALYNOFACIES SIGNATURES OF LITHOSTRATIGRAPHIC UNITS AT SITE 959, ODP LEG 159 (CÔTE D'IVOIRE-GHANA TRANSFORM MARGIN)

Francisca E. Oboh, Oscar Yepes, and ODP Leg 159 Shipboard Scientific Party

Department of Geology and Geophysics, University of Missouri-Rolla, Rolla, MO 65401

Site 959 was one of four sites drilled on Ocean Drilling Program (ODP) Leg 159 in the Côte d'Ivoire-Ghana Transform Margin (eastern Equatorial Atlantic), January-February, 1995. Approximately 1160 meters of stratigraphic section (mid-Cretaceous-Pleistocene) was cored in four holes, and it represents the most complete stratigraphic record among the four sites drilled on this leg. Five lithostratigraphic units were identified. Going downsection, these units are as follows: Unit I, Pleistocene to early Miocene in age, consists of nannofossil foram ooze, which grades downhole to nannofossil chalk with forams. It is further divided into two subunits. Unit II is early Miocene to late Paleocene in age and has three subunits: Subunit IIA consists of diatomite interbedded with nannofossil chalk and clay; Subunit IIB is characterized by black chert and claystone; while porcellanite with micrite and clay comprises Subunit IIC. Black claystones of late Paleocene to early Coniacian age comprise Unit III. Unit IV is dated as early Coniacian to early Turonian and possibly older, and has two subunits: Subunit IVA consists of sandy limestone, sandy dolomite and calcareous sandstone, while Subunit IVB has limestones. Unit V, which is late Albian, is characterized by interbedded claystones, siltstones and sandstones, and is separated from Unit IV by an unconformity. These lithostratigraphic units all accumulated under marine conditions.
Eighty-six samples from holes 959A and 959D have been analyzed for palynofacies using transmitted light microscopy. Fluorescence light microscopy was used to differentiate between marine-derived and terrestrially-derived amorphous organic matter. Twelve types of dispersed organic matter were identified, and their relative abundances were subjected to cluster analysis. Five groups of organic matter (A-E) and seven groups of samples (1-7; palynofacies assemblages) are present in the dataset. Group A comprises amorphous organic matter only, but group B consists of black debris and wood, while group C is characterized by black-brown fragments. Marine palynomorphs (dinocysts, foram linings), plant tissue, cuticles and yellow-brown fragments comprise group D while group E consists of fungi, pollen/spores, resins and algae. Amorphous organic matter has played the most significant role in defining all the palynofacies assemblages, but black debris and wood are next in importance. These assemblages show some correlation with lithostratigraphic units and depositional environments. Palynofacies assemblages 1 and 2 characterize Lithologic Unit V, which represents the most proximal depositional environment, with the lowest amount of amorphous organic matter and highest amounts of wood and related organic matter (i.e., black debris and black-brown fragments). It has the highest thermal maturation index which has been derived from palynomorph color. The drastic increase in amorphous organic matter and decrease in black debris above Unit V probably support the placement of an unconformity between Units IV and V. The lithostratigraphic units and amounts of amorphous organic matter for assemblages 3 to 7 are as follows: assemblage 3 (basal IB; 30-35%), assemblage 4 ( IB, IIA; 55-65%), assemblage 5 (IB, IIA, III; 55-65%), assemblage 6 (IIA, IIC, III; 65-78%), and assemblage 7 (IIB, IIC, III; >78%). Palynofacies assemblage 7 represents the most distal environments drilled at Site 959. Thus, changes in the amount of amorphous organic matter are related to proximal-distal positions of depositional environments, and permit the reconstruction of paleobathymetric curves. This palynofacies data will be integrated with biostratigraphic and other data and used to correlate Site 959 with sites 960-962.

HUMAN INFLUENCE IN THE HOLOCENE VEGETATION OF NORTHERN SPAIN FROM POLLEN ANALYSIS

M. Cristina Peñalba

Centro de Ecología - UNAM, A.P. 1354, 83000 Hermosillo, Sonora, Mexico

Human influence in the vegetation is recorded since 7,000-6,000 BP in pollen diagrams from northern Spain. Variations in the date of the first anthropic features are related to the intensity of the colonization by agricultural civilizations. The northern Cantabrian region is mountainous and was not so suitable for agriculture as the great valleys and the meseta, so it was less colonized and human interference in the landscape was less severe. Pollen diagrams record human action there much later, after 3,000 BP.
The first indicators of agriculture in pollen diagrams consist of the sudden diminution of arboreal pollen frequencies and increase in herbs, mainly Poaceae. At the same levels, changes in the absolute pollen concentration are recorded and the sediment gets gravelly. In some cases, cereal-type pollen grains are present. This seems to reflect slash and burn techniques.
After 3,000 BP, the effects of human action became stronger with time: arboreal pollen diminution became irreversible. Such was the case of the Holocene dominant trees Quercus, Corylus and Fagus, which tended to play a secondary role in the vegetation, replaced by shrubs and herbs. Cereals became more abundant. Meanwhile, new arboreal species were introduced or more intensively grown, such as Castanea, Juglans, Vitis and Olea. In the latest century, reafforestations of local and exotic trees contributed to wider changes in the landscape.
But the strongest effect, from a dynamics point of view, may be the interruption of the Late Holocene European tree migrations that went through the Pyrenees into Spain. In this sense, Fagus, Abies and Carpinus, which had a wider geographic distribution in the Peninsula during the last interglacial, are today restricted to some particular sites on the Spanish slope of the Pyrenees (Abies and Carpinus) or cover just part of northern Spain (Fagus), excluding some climatically suitable regions. Pollen evidence supports the idea that these changes could have been due to human influence.

PALYNOLOGY AND DEPOSITIONAL HISTORY OF PLEISTOCENE SEDIMENTS FROM ULMERS POND, VALDOSTA, GEORGIA, U.S.A.

Fredrick J. Rich

Department of Geology and Geography, Georgia Southern University, Statesboro, Georgia 30460-8149, U.S.A.

Ulmers Pond is a karst depression located in Valdosta, Loundes County, Georgia. In February, 1993, the U.S. Geological Survey, under the direction of Dr. Helaine Markewich, collected a core of sediment from the site. Rotary drilling resulted in almost complete recovery of 6 cm diameter core to a depth of 40.5 m; there was variable compaction. Core sections were cut in half and described; plant clasts and palynological samples were collected for analysis and dating. Preliminary results show the following: 1) the upper 738 cm have ages of 5,760 yrs or less; below 738 cm there is a clay/charcoal layer approximately 20 cm thick; 2) below about 766 cm radiocarbon dates exceed 32,000 years; 3) ten charcoal or charcoal-bearing levels indicate recurring fires; 4) seeds recovered from 15 horizons prove the presence of Nymphaea, Nuphar and Brasenia since peat accumulation began; 5) pollen samples show that plant communities similar to existing ones have occupied the site. Pinus and Quercus are dominant, though shrubs, herbs (particularly the Compositae) and freshwater algae contributed significantly to the pollen flora. Meagre representation of boreal taxa has been demonstrated thus far. These characteristics conform to interpretations drawn by Watts, Grimm, and others from similar sites in the region.

POLLEN INFLUX FROM LAKE DOLBEAU, MCGERRIGLE MOUNTAINS, GASPE PENINSULA, QUEBEC: A PROXY FOR THERMAL CLIMATE AND FOR SOLAR ACTIVITY?

Pierre J.H. Richard and Pierre Gangloff

Département de géographie, Université de Montréal, C.P. 6128 Centre ville, Montréal, Quebec H3C 3J7, Canada

Pollen influx (pollen accumulation rate expressed as the number of grains/cm2/year) is a result of plant abundance, pollen production and sedimentological processes. Lake Dolbeau is small (4 ha), dimyctic, and the net rate of sediment accumulation in the central 6 m long core is provided by seven radiocarbon dates. Apart from the silty basal 30 cm, the sediment is homogenous gyttja spanning the last 10,000 radiocarbon years. The total pollen influx curve (trees, shrubs, herbs) shows large fluctuations interpreted as climatically-induced changes in biomass or pollen production within the lake's pollen source-area. There is an especially important cooling event centered on 8,000 BP followed by a slow recovery culminating around 5,000 BP. Very similar and synchronous trends in total pollen influx are present at Moulton Pond (Maine) and at Rogers Lake (Connecticut). When the chronology is calibrated in calendar years (dendro years), the major shifts and many minor shifts in the Lake Dolbeau's pollen influx curve correspond closely to the delta 14C curve. The delta 14C curve (the difference between the actual dendro age and the radiocarbon age) is a measure of the variation in the production of radiocarbon isotopes in the upper atmosphere. It is most probably a measure of the variation in solar activity during the Holocene superimposed over the long-term change in the terrestrial magnetic shield, the input of cosmic rays being assumed to be constant over the period.

RECENT PALYNOMORPH SEDIMENTATION IN PLAYA MEDINA (NE VENEZUELA) IN RELATION TO
VEGETATION AND SEDIMENTARY ENVIRONMENTS

Valentí Rull1 and Teresa Vegas-Vilarrúbia2

1 MARAVEN, Exploración. Ap. 829, Caracas 1010-A. Venezuela
2 GEOHIDRA, Div. Ambiente, Dpto. Ecología y Calidad Ambiental. Ap. 47851. Caracas, Venezuela

The method of modern analogs is widely used in paleoecological and paleoenvironmental reconstructions based on palynology. One of the first steps of this method consists of the characterization of present-day or recent patterns of palynomorph sedimentation. The present study is a contribution to the knowledge of palynomorph sedimentation patterns in a small coastal basin, occupied by Conocarpus erectus and Rhizophora mangle mangroves, brackish marshes with Acrostichum aureum and herbs, slope forests, and crops of Cocos nucifera. Samples were taken along a longitudinal transect from the beach to the slope forests, embracing the entire basin. All the palynomorphs found were identified or labelled, and counted.
Overall, fungal remains are dominant in both abundance and taxonomical richness, followed by sporomorphs, algae, Incertae sedis and animal remains. The areal distribution of fossils allowed recognition of three main sedimentary domains: (1) crops of Cocos nucifera and slope forests, (2) mangrove and (3) ecotones and flooded areas other than mangrove. The more abundant fungal spores were those of Glomus and Anthostomella-type, as well as Diporisporites and others not identified. Among the sporomorphs, Chenopodiaceae-Amaranthaceae, Acrostichum, Cyperaceae and Gramineae were the more abundant, followed by Cocos and Rhizophora. Trachelomonas? was the dominant alga, whereas Amphitrema, Centropyxis and foraminiferal linings (all of them belonging to the Rhizopoda) were the more important animal remains. The objective analysis of association (clustering) permitted classification of the samples, as well as the definition of the more significant palynomorph assemblages. In summary, the spatial arrangement of the sedimented palynomorphs turned out to be heterogeneous, and closely related to both vegetation and sedimentary subenvironments. This is encouraging with respect to the development of paleoecological studies on ancient sediments from the same basin, as well as others with similar characteristics.

PALYNOLOGICAL AND PALEOENVIRONMENTAL ANALYSIS OF THE BITUMEN-SATURATED CLEARWATER FORMATION (EARLY ALBIAN, EARLY CRETACEOUS) AT COLD LAKE, ALBERTA, CANADA

R.P.W. Stancliffe and B.A. Cheadle

Imperial Oil Resources Ltd, Research Center, 3535 Research Road, N.W., Calgary, Alberta T2L 2K8, Canada

Palynomorphs have been studied from the shales of the Clearwater Formation (early Albian) of north central Alberta for over thirty years by both industrial and academlc palynologists. Well-preserved marine and terrestrial forms were recorded but little research has been completed on the organic matter in the sandier sediments from the Cold Lake area, east Alberta. These are commonly saturated with bitumen which can obscure the sedimentology and lithostratigraphy. Recent research has completed a revision of the regional sequence stratigraphy using organic-matter assemblage distribution as one of the data sets.
Imperial Oil Resources Limited, which operates the Cold Lake oil field, has a unique collection of closely-spaced cores cut from the Clearwater Formatlon. Over 20 cores have been examined and samples collected from all the lithologies recorded. It was found that standard palynological processing techniques had to be modified to remove the bitumen from saturated samples. This was achieved by using toluene as a solvent which, when used with care, caused no damage to the palynomorphs.
Dominant dinoflagellate cysts within the sediments include Palaeoperidinium cretaceum, Cleistosphaeridium? multispinosum and Circulodinium spp. However, no fully marine assemblages have been found such as those previously reported from the Clearwater shales. Also very few small acritarchs, microforaminiferal linings and cavate dinoflagellate cysts have been observed. Terrestrial palynomorphs include small spores such as Stereisporites antiquasporites and the pollen grains Classopollis classoides and Alisporites bilateralis. The organic matter is dominated by wood remains and amorphous matter. Five major assemblages of palynomorphs and organic matter can be discriminated and correlated with the depositional model developed using sedimentological concepts and trace fossil assemblages. Also, third order and some fourth order sequence boundaries can be resolved by changes in the overall organic matter assemblages. Using this data, the Clearwater sediments at Cold Lake are thought to have been deposited in late lowstand to early transgressive systems tracts as a number of tidal deltaic valley-fill sequences.

NON-MARINE ALGAL CYSTS FROM LOWER
PALEOZOIC PARALIC ROCKS

Paul K. Strother

Department of Geology & Geophysics, Boston College Weston Observatory, Weston, Massachusetts 02193, U.S.A.

Some of the best-preserved Silurian and older assemblages of non-marine palynomorphs occur in mudstones interbedded with sandstones rich in trace fossils. These sequences, with abundant Cruziana and Rusophycus, can be quite depauperate in normal marine body fossils. But the same units have the potential to preserve a diverse palynoflora, as has been demonstrated for the Silurian Tuscarora Formation of Pennsylvania and the Middle Ordovician Hanadir Shale in Saudi Arabia. In these rocks, the cryptospores recovered represent convincing evidence of the presence of land-dwelling plants that had evolved beyond an algal grade.
The recent discovery of membrane-enclosed cells and cell clusters from the Middle Cambrian Bright Angel Shale in Arizona opens up the possibility that fresh-water algae may have contributed significantly to the "leiosphere" fraction that typically dominates shallow marine palynological assemblages in the lower Paleozoic. These presumed algal cysts are quite unlike the typical marine acritarchs which would normally occur in reduced fine-grained siliciclastics from this period. Morphologically, this fossil assemblage is comparable to the population-level variation that occurs when the extant freshwater alga, Oöcystis lacustris (?) is transported into brackish water, forming Tetradeon-like morphologies.
Pre-Devonian deposits that have preserved terrestrial organic remains are exceedingly rare. The palynological assemblage from the Bright Angel Shale, while remaining problematic, quite probably represents a rare glimpse into the fossil remains of freshwater, hence "terrestrial," organisms from the Middle Cambrian. The enclosing membranes of resistant organic composition which characterize these fossils seem to be a trait that carries over to early embryophytic cryptospores occurring in the Ordovician.

RECENT VEGETATION DYNAMICS IN THE COASTAL RAINFORESTS OF SOUTHERN CHILE

Julian M. Szeicz

Department of Geography, Queen's University, Kingston, Ontario K7L 3N6, Canada

Although southern South America is the only extensive land mass in the mid to high latitudes of the Southern Hemisphere, little information is available on the interactions of recent climate change, disturbance, and vegetation dynamics in the temperate rainforests of the region. The few long proxy climatic records that are available from southern South America (based on tree-rings) indicate that long-term changes in both temperature and precipitation have occurred over the past millenium. The impact that these changes have had on vegetation, however, has not yet been resolved; high resolution paleoecological records of vegetation change during the past millenium are nearly nonexistant in this region. Dendroecological studies have stressed the importance not of climatic change, but of large-scale disturbances such as vulcanism, earthquakes, and avalanches in driving forest dynamics at the decadal to century scale. More information is thus needed on the relative importance of climate change and natural and anthropogenic disturbance in driving vegetation dynamics at the century to millenial timescale.
Here I use high resolution palynological analyses of lake sediments to demonstrate the contrasting histories of recent vegetation dynamics at two sites in southern Chile. Lago Miranda is located in very humid temperate rainforest within a kilometre of the Pacific coast at 46š15'S. The forest is anthropogenically undisturbed, and has a diverse composition, dominated by the genera Drimys, Podocarpus, Pilgerodendron, Nothofagus, Tepualia, Pseudopanax, Weinmannia and Caldcluvia. Lago Venus is located in a less humid area which has been cleared for grazing and conifer plantations during the 20th Century, about 70 km inland from the coast at 45š30'S. The original forests around Lago Venus, some of which remain today, were dominated almost entirely by the genus Nothofagus (coigue, or southern beech).
Dates are not yet available, but the 70-80 cm cores collected at each site, sampled contiguously at 1 cm intervals, probably represent 1,000 to 2,000 years of sedimentation. Although dominated by Nothofagus, a notorious overproducer of pollen in the southern hemisphere, the pollen record from Lago Miranda is diverse and fairly representative of the surrounding vegetation today. Short-term fluctuations, possibly due to periodic disturbances such as volcanic activity and/or earthquakes, appear to be superimposed on a long-term decrease in the abundance of Nothofagus pollen. For most of the core, the palynological record from Lago Venus is dominated by Nothofagus pollen almost to the exclusion of other types. Evidence for extensive (colonial) anthropogenic disturbance is found in the uppermost 5-10 cm of the core.
Although still in their preliminary stages of analysis, these records represent the first high resolution palynological studies from southwestern South America. The planned integration of paleoecological and dendroecological data from these sites should help to improve understanding of century scale vegetation dynamics in this remote and poorly studied region.

IMPLICATION OF THE DISCOVERY OF REWORKED AND IN SITU LATE PALEOZOIC AND TRIASSIC PALYNOMORPHS ON THE EVOLUTION OF SIRT BASIN, LIBYA

Bindra Thusu

Exploration Division, Arabian Gulf Oil Company, P.O Box 263, Binghz, Libya, G.S.P.A.J.

The origin and age relationships of the Paleozoic and continental Mesozoic sediments in the Sirt Basin have remained obscure due to a scarcity of fossils. Palynological examination of sediments from the eastern flank of the Kalash Trough, Sarr 'C' Main Trough and western Ab Attiffel Graben in the southeast Sirt Basin has revealed the presence of reworked marine and non-marine Late Paleozoic palynomorphs in Mesozoic sediments. In situ and reworked palynomorphs are also recognized in the Waddn Shelf and Tagrifet Trough in the western Sirt Basin. The discovery of these palynomorphs is evidence of sedimentation during the Late Paleozoic spreading across the intra-cratonic basin of North Africa. Furthermore, the recently reported (El-Arnauti et al., 1985) discovery of well-preserved Triassic palynomorphs in lacustrine-lagoonal shales within the ml Formation (formerly Cambro/Ordovician) in Kalash Trough extends the Early Mesozoic sedimentation to Triassic times in the Sirt Basin.
Available biostratigraphic data permit the prediction of Silurian/Devonian and Early Carboniferous sediments preserved in grabens created by the Hercynian Orogeny. The presence of Late Carboniferous-Permian volcanoclastics and Triassic sediments represents the first Hercynian sedimentary fill of proto-Sirt Basin grabens.
These findings conflict with those of Bonnefous (1972) and Massa and Delort (1984), who postulated non-deposition of sediments in Sirt Basin from the Ordovician to the Jurassic, but are in agreement with Hea (1969) who predicted, on regional geological evidence, that the continental Mesozoic in the southern Sirt Basin may contain basal beds ranging in age from Paleozoic to Early Cretaceous. The existence of additional sedimentary sequences hitherto thought to be missing should be taken into consideration for future hydrocarbon exploration in Sirt Basin.

CHRONOSTRATIGRAPHIC CORRELATION OF THE MISSISSIPPIAN BORDEN GROUP OF THE NORTHERN ILLINOIS BASIN

Gordon D. Wood1, Leonard E. Eames1 and Lloyd C. Furer2

1 Amoco Production Company, P.O. Box 3092, Houston, Texas 77253-3092, U.S.A.
2 Indiana Geological Survey, 611 North Walnut Grove, Bloomington, Indiana 47405, U.S.A.

The geographic and stratigraphic distribution of palynomorphs within the Early to "Middle" Mississippian of the United States is not well documented. Well-preserved assemblages from this interval have been recovered from a surface exposure in Illinois and from two coreholes in Indiana. Samples analyzed are from the following three locations in the northern Illinois Basin: 1, type section of the Warsaw Shale, Hancock County, Illinois; 2, Borden Group (undifferentiated) Indiana Geological Survey Drill Hole 328, Fountain County, Indiana; and 3, Borden Group (undifferentiated) Indiana Geological Survey Drill Hole 331, Warren County, Indiana.
The assemblage is dominated by new species. Many can be assigned to the following genera: Apiculatisporis, Auroraspora, Cirratriradites, Crassispora, Cyclogranisporites, Densoporites, Discernisporites, Duvernaysphaera, Grandispora, Granulati-sporites, Grumosisporites, Lophozonotriletes, Neoraistrickia, Punctatisporites, Radiizonates, Raistrickia, Retusotriletes, Spelaeotriletes, Unellium, Vallatisporites and Verrucosisporites. The assemblage cannot be directly compared to the spore zones (PC, CM, and PU) of western Europe, suggesting phytogeographic diversification between the two regions. The microflora is pre-Lycospora and contains Vallatisporites/Radiizonates types not assignable to the older (e.g., Kinderhookian) part of the geological column. These data suggest that an unconformity may exist in Fountain County where the Rockford Limestone may be the only Kinderhookian present above the Late Devonian New Albany Shale. Geophysical logs have been integrated with palynological data to subdivide the Borden Group into time intervals and to correlate them to the limestone formations (i.e., Choteau, Burlington, Keokuk and Ullin limestones) of the Burlington-Keokuk shelf of west central Illinois. This chronostratigraphic correlation will allow paleogeographic mapping of time intervals within the Borden Group.
Sandstone is prevalent in the lower half of the Borden Group from Fountain County, west central Indiana to Coles County, east central Illinois. Siltstone dominates the Borden from Coles County to Fayette County, of central Illinois. The siltstone most likely interfingers across Montgomery County, Illinois with carbonates which become abundant in Macoupin County, west central Illinois. Future work will extend this analysis to the southern part of the Illinois Basin where it should be useful in delineating potentially productive reservoir hydrocarbon facies in the Warsaw Shale, which is time equivalent to the upper Borden of west central Indiana.

PHYTOGEOGRAPHIC SIGNIFICANCE OF POLLEN AND SPORES FROM FUYANG BASIN COALS, ANHUI PROVINCE, PEOPLE'S REPUBLIC OF CHINA

Gordon D. Wood1 and Ouyang Shu2

1 Amoco Production Company, P. O. Box 3092, Houston, Texas 77253-3092, U.S.A.
2 Nanjing Institute of Geology and Palaeontology Academia Sinica, Chi Ming Ssu, Nanjing, People's Republic of China

Core samples from two wells of the Fuyang Basin have yielded an extremely well preserved and diverse assemblage of pollen and spores. The assemblage includes Anticapollis tornatilis, Apiculatisporites spinulistratus, Bactrosporites shaoshanensis, Calamospora sterosa, Crassispora kosankei, C. orientalis, Densosporites muricatus, Dictyotriletes reticulocingulum, Falcisporites nuthallensis, Florinites florinii, F. mediapudens, Gravisporites shanxiensis, Gulisporites cochlearis, G. laevigatus, Kaipingispora ornatus, Lophozonotriletes yanzhouensis, Macrotorispora gigantea, M. media, Perocanidospora clatrata, Pityosporites tongshanii, Platysaccus insignis, Radiizonates solaris, Raistrickia sp., Schizaeisporites microrugosus, Schopfipollenites sp., Shanxispora cephalata, Striatopodocarpites fusus, Striatosporites irregullaris, Striolatospora major, Sulcatisporites ovatus, Torispora acanthus, T. attenuatus, T. hunanensis, T. incisus, T. securis, T. sinensis, T. tribullatus and Vesiculatisporites meristus.
The section penetrated by these wells are assignable to, oldest to youngest, the Shanxi and Shihezi formations. Certain aspects of the microflora are very similar to assemblages that dominate the Upper Carboniferous (Westphalian-Stephanian) of the Euramerica floral province. These include Macrotorispora, Torispora, Radiizonates and Triquitrites which become extinct or exhibit a marked decline at the Carboniferous-Permian boundary in Euramerica. The presence of these taxa in the Permian-Cathaysian floral realm indicates that conditions in the South China Plate were tropical-subtropical. During the Permian this region acted as a refugium for the parent plants. This supports paleogeogaphic information that suggests the South China Plate has moved northward since the Permian time.

LATE QUATERNARY PALEOECOLOGY OF THUJA AND JUNIPERUS (CUPRESSACEAE) AT CRAWFORD LAKE, ONTARIO: POLLEN, STOMATA AND MACROFOSSILS

Yu Zicheng

Departments of Botany, University of Toronto and Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada

In northeastern North America, paleoecological records of Thuja and Juniperus are problematic due to their indistinguishable and poor-preserved fossil pollen grains (but see Parent and Richard, 1990). Their separation would provide valuable information in paleoecological interpretation of pollen data due to their different habitats.
Macrofossils are distinctive, but due to the time-
consuming nature of macrofossil analysis and scarcity of macrofossils in pollen cores, a few pollen investigations have accompanied macrofossil studies. In this study, I use distinctive Thuja and Juniperus stomata as a proxy of macrofossils (Hansen, 1995) to investigate this problem. Stomatal analysis uses pollen slides, and thus it requires no extra preparation time. Also stomata are more abundant (x103/mL.) than macrofossils (x10š/mL). Pollen size was also measured because Thuja tends to be larger than Juniperus (Parent and Richard, 1990). Macrofossil analysis was carried out to verify the pollen and stomatal results.
Crawford Lake has 5-15% Thuja-Juniperus pollen through most of the past 13 ka except for a dearth during the Pinus zone at 10-8 ka. Macrofossil, stomatal and pollen results indicate the late glacial pollen mostly derived from Juniperus (likely communis), whereas pollen at 8-0 ka was from Thuja. This bi-modal pattern of Thuja-Juniperus pollen appears at other sites in southern Ontario despite its variable abundance. The late glacial Thuja macrofossils reported by Warner (1982) and Anderson (1982) may indicate early immigration of a small population via the favorable habitats along the Niagara Escarpment or alternatively recycled/contaminated Thuja macrofossils, as suggested by the questionable stratigraphies and the puzzling 14C dates.

POSTGLACIAL PALEOHYDROLOGY AT CRAWFORD LAKE, ONTARIO: DRY CLIMATE TRIGGERED MID-HOLOCENE HEMLOCK DECLINE?

Yu Zicheng and Jock McAndrews

Departments of Botany, Royal Ontario Museum and University of Toronto, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada

Lithology, geochemistry, pollen and/or plant macrofossil data from five cores are used to reconstruct postglacial lake history. The bedrock basin (2.4 ha in area, 30 m deep) was probably formed by hydraulic mining during a catastrophic meltwater rush. The lake was formed shortly after the ice retreat at ~13 ka, suggested by absence of till or other glacial deposits. The earliest sediments were silty/sandy clay, likely eroded from treeless tundra upland or derived from glacial Lake Whittlesey. From ~13 to 12 ka, lake levels were at least 1.5 m lower than today, as suggested by the missing basal tundra and a very brief spruce zone in a lakeside wetland core and an elevation constraint of the bedrock outlet sill at 1.5 m below the present lake level. Autochthonous marl replaced clay throughout the basin with tree immigration to the watershed. During the spruce pollen zone (~12-10 ka), reduced upland erosion and slope stabilisation was indicated by increased organic matter and carbonate and by decreased erosion-indicator elements (Ti, Al, K, Na, V, Mg). During the following pine and early mixed forest zones, marl continued to be deposited. In the middle of the hemlock maximum zone (~6 ka), laminated sediments started to form in the deep basin.
The upland hemlock population decline at ~4.8 ka corresponds closely with basin-wide lithologic changes: (1) laminations disappeared from the deep basin along with a lithologic change from marl to marly gyttja; (2) two shallow cores contain a moss layer (inwashed?), also with a shift from marl to more organic-rich sediments; and (3) two wetland cores show sediment hiatuses from ~5 and ~8 to 2 ka, indicating nondeposition and/or erosion due to lowered lake level. From ~4.8 to ~2 ka detritus layers (inwashed) were deposited in a shallow core, also indicating lowered and fluctuating levels. Laminations in the deep core disappeared from 3.5 to 2.1 ka. An underwater bedrock platform at 5 m depth formed during the lower lake levels by freeze-thaw cycle. The mid-Holocene low lake level was caused by dry/warm climate. Rising lake level in the past 2,000 years, due to a cool/moist climate, renewed lamina deposition in the deep core, homogeneous marl deposition in the shallow cores, and peat accumulation in wetland cores.
This warm/dry period in the late mid-Holocene appears at other sites in southern Ontario, e.g., Rice Lake, Decoy Lake, and Sunfish Lake. It correlates in time with the dry period in the midwestern United States, which shows a time-transgressive trend from 8-5 ka in northwestern Minnesota to 5-3 ka in southeastern Wisconsin and southern Michigan. This regional dry/warm climate, starting at ~5 ka, might have triggered the hemlock decline because: (1) drought is the most serious damaging agent to this species, especially for seedlings in winter; (2) newly-immigrated hemlock in its westernmost range at ~5 ka was likely established in non-optimal habitats due to competition from other species; and (3) a reduced hemlock population persisted after the decline, probably in protected moist habitats. A drought-weakened hemlock population would be vulnerable to attack by a possible pathogen, which may have subsequently spread through the range of hemlock. This hypothesis might be tested by examining the trend in ages (14C or varves) for the decline from Michigan to the southern Appalachians or Nova Scotia, which may even provide evidence for the origin and path of the pathogen outbreak.