Late Quaternary Vegetation Development in South-Central Illinois

1972 ◽  
Vol 2 (02) ◽  
pp. 217-231 ◽  
Author(s):  
Eberhard Grüger

Pollen and macrofossil evidence for the nature of the vegetation during glacial and interglacial periods in the regions south of the Wisconsinan ice margin is still very scarce. Modern opinions concerning these problems are therefore predominantly derived from geological evidence only or are extrapolated from pollen studies of late Wisconsinan deposits. Now for the first time pollen and macrofossil analyses are available from south-central Illinois covering the Holocene, the entire Wisconsinan, and most probably also Sangamonian and late Illinoian time. The cores studied came from three lakes, which originated as kettle holes in glacial drift of Illinoian age near Vandalia, Fayette County. The Wisconsinan ice sheet approached the sites from the the north to within about 60 km distance only.One of the profiles (Pittsburg Basin) probably reaches back to the late Illinoian (zone 1), which was characterized by forests with muchPicea. Zone 2, most likely of Sangamonian age, represents a period of species-rich deciduous forests, which must have been similar to the ones that thrive today south and southeast of the prairie peninsula. During the entire Wisconsinan (14C dates ranging from 38,000 to 21,000 BP) thermophilous deciduous trees likeQuercus, Carya, andUlmusoccurred in the region, although temporarily accompanied by tree genera with a more northerly modern distribution, such asPicea, which entered and then left south-central Illinois during the Woodfordian. Thus it is evident that arctic climatic conditions did not prevail in the lowlands of south-central Illinois (about 38°30′ lat) during the Wisconsinan, even at the time of the maximum glaciation, the Woodfordian. The Wisconsinan was, however, not a period of continuous forest. The pollen assemblages of zone 3 (Altonian) indicate prairie with stands of trees, and in zone 4 the relatively abundantArtemisiapollen indicates the existence of open vegetation and stands of deciduous trees,Picea, andPinus. True tundra may have existed north of the sites, but if so its pollen rain apparently is marked by pollen from nearby stands of trees. After the disappearance ofPinusandPiceaat about 14,000 BP (estimated!), there developed a mosaic of prairies and stands ofQuercus, Carya, and other deciduous tree genera (zone 5). This type of vegetation persisted until it was destroyed by cultivation during the 19th and 20th century. Major vegetational changes are not indicated in the pollen diagram for the late Wisconsinan and the Holocene.The dating of zones 1 and 2 is problematical because the sediments are beyond the14C range and because of the lack of stratigraphic evidence. The zones dated as Illinoian and Sangamonian could also represent just a Wisconsinan stadial and interstadial. This possibility, however, seems to be contradicted by the late glacial and interglacial character of the forest vegetation of that time.

1989 ◽  
Vol 26 (3) ◽  
pp. 551-560 ◽  
Author(s):  
Willem J. Vreeken

New observations in the Lethbridge area permit a more complete reconstruction of the landscape history in Late Wisconsinan and Holocene time. The plain of glacial Lake Macleod, the Lethbridge moraine, and the plain of glacial Lake Lethbridge became exposed in that order and in quick succession. Almost immediately thereafter, a discontinuous mantle of loess began to accumulate on those surfaces. The presence of Glacier Peak layer G or Manyberries tephra near the base of the loess indicates these events occurred just before 11 200 BP. The similarity of this chronology to that established for the older Green Lake end moraine in the Cypress Hills region and the fact that the younger Buffalo Lake moraine was formed before 11 000 BP indicate that deglaciation of southern Alberta proceeded very rapidly.The oldest buried paleosol observed near Lethbridge began to form shortly after 11 200 BP. Subsequently, and throughout the Holocene, intervals of loess deposition alternated with soil-forming intervals. At least six soil–landscape cycles occurred between 11 200 and 6800 BP (before the Mazama tephra was deposited), and at least five cycles occurred subsequently. Occurrences of postglacial loess more than 3 m thick are common. A column of 6.7 m of loess, including 12 paleosols, was observed at one site.


2000 ◽  
Vol 37 (6) ◽  
pp. 849-861 ◽  
Author(s):  
E Kotler ◽  
C R Burn

Four late Quaternary cryostratigraphic units are recognized in the unconsolidated valley-bottom deposits of the Klondike area, Yukon Territory. Three of the units, in ice-rich, loessal sediments of pre-Wisconsinan or Wisconsinan age, collectively compose the King Solomon Formation. They are overlain by a Holocene organic unit. The units are distinguished by their cryostratigraphic characteristics and oxygen-isotope ratios of included ground ice. The basal unit is the Last Chance Creek Member, a pre-Late Wisconsinan deposit, containing preserved ice wedges δ18O ~ -28 to -26‰; δD ~ -225 to -209‰). The overlying Quartz Creek Member, a Late Wisconsinan unit, is dominated by organic-rich loess. Massive ice is noticeably absent, although the sediments are ice rich. The isotopic composition of ice in this unit is characteristic of full-glacial conditions (δ18O ~ -32 to -29‰; δD ~ -234 to -257‰). An abrupt change to warmer and wetter conditions at the end of glaciation, prior to the Holocene, is recorded by the ice-rich, colluviated Dago Hill Member (δ18O ~ -28 to -21‰; δD ~ -164 to -225‰), which began accumulating by 11.62 14C ka BP. Large ice wedges originate in this unit, and, in places, penetrate the underlying full-glacial sediments. Even higher δ18O and δD values occur for ice in the Holocene organic unit (δ18O ~ -25 to -20‰; δD ~ -164 to -189‰). The majority of the massive icy bodies in the King Solomon Formation are ice wedges, but pool ice and aggradational ice are also exposed, especially in the Dago Hill Member. Massive icy beds formed by groundwater intrusion into permafrost occur at the lower contact of the Quartz Creek Member.


1997 ◽  
Vol 45 (3) ◽  
pp. 549 ◽  
Author(s):  
P. J. Lloyd ◽  
A. P. Kershaw

A pollen diagram from Morwell Swamp provides a record of vegetation and climate through the Holocene period while the application of a bioclimatic analysis of the aquatic species Brasenia schreberi to the occurrence of its pollen in the record allows the first quantitative reconstruction of early Holocene climate from mainland south-eastern Australia. The beginning of the Holocene, c. 10000 years before present (BP), was marked by the establishment of permanent water within the basin and an expansion of forest under conditions of increasing precipitation and probably also temperature. The early Holocene forests were dominated by Casuarinaceae, a situation typical of lowland south-eastern Australia. The presence of Brasenia schreberi Gmel., a species now restricted to lower latitudes, suggests that, by c. 9000 years BP, mean annual temperatures had risen to slighly above today’s values, while summer temperatures may have been at least 1.3˚C higher. These results are surprising considering that most previous evidence has suggested that optimal climatic conditions were achieved between about 7000 and 5000 years ago, and that radiation levels are predicted, from Milankovitch forcing, to have been lower than today at this time in the Southern Hemisphere. It is clearly necessary to be somewhat cautious about the wholescale acceptance of the quantitative values at this stage, although they are not contradicted by other palynological data. Subsequent regional increases in the wetter forest elements, Nothofagus and Pomaderris, indicate a middle Holocene peak in precipitation, although it is estimated, from a bioclimatic analysis of Nothofagus, that summer temperatures had become substantially lower than today. This lowering may have been due to a local or regional increase in cloud cover. There is evidence for minor variation in vegetation and climate within the late Holocene, which is consistent with evidence from elsewhere within the region.


The Holocene ◽  
2019 ◽  
Vol 29 (8) ◽  
pp. 1263-1272 ◽  
Author(s):  
Joseph R McAuliffe

Silt-rich and clay-rich vesicular horizons (V horizons) that develop beneath desert pavements limit infiltration and plant-available soil moisture. A radiocarbon date from buried charcoal constrains the timing of emplacement of a Sonoran Desert alluvial fan deposit to the very end of the Pleistocene (approximately 12.7 ka). The surface of the fan is dotted with 1.5–3 m light-colored plant scars that mark places once occupied by larger perennial plants. A few very large, ring-like clones of Larrea tridentata have persisted on the surface and represent plants that may have initially established as long ago as the early Holocene. The gravelly fan deposit initially would have possessed high infiltration capacities and fostered the establishment of vegetation. Two principal sets of factors have driven vegetation change over the course of the Holocene. During the first part of the Holocene, differences in life history attributes of various species (dispersal and colonization vs. competitive abilities) would have contributed to a succession of perennial plant occupants, culminating with the predominance of the slow-growing, long-lived, but competitively dominant L. tridentata. During the latter part of the Holocene and continuing to the present, continued development of the pavement and associated V horizon has increasingly diminished the capacity of the surface to absorb precipitation and is responsible for the more recent phase involving progressive elimination of vegetation. Development of soil features that markedly influence soil hydrology is a major component of vegetation change during the late Quaternary in the more arid portions of the Sonoran and Mojave deserts.


1989 ◽  
Vol 26 (10) ◽  
pp. 1990-2002 ◽  
Author(s):  
Arnaud Héquette ◽  
Philip R. Hill

This paper describes the seismic stratigraphy of the Quaternary sediments on the inner shelf (< 20 m water depth) of the Canadian Beaufort Sea, seaward of the Tuktoyaktuk Peninsula. Two regional unconformities and three seismic sequences are defined from the high-resolution seismic records. The deeper sequence (sequence III) is characterized by large-scale cross-beds. This sequence has been correlated with the Tingmiark Sand lithostratigraphic unit, which was previously defined farther offshore and is thought to be a glaciofluvial unit deposited during lower-than-present sea-level conditions in the Late Wisconsinan. The lower boundary of the overlying sequence (sequence II) is an unconformity (u/c 2), interpreted as the pre-transgression land surface. Sequence II is discontinuous and consists of localized basin-fill and channel-fill units. Most of these are remnants of thermokarst lakes partially eroded during the Holocene transgression. This sequence is separated from the uppermost sequence (sequence I) by another unconformity (u/c 1), which is the shoreface erosion surface generated by the Holocene sea-level rise. Sequence I is composed of a transgressive sand sheet overlain, in deeper areas, by recent marine muds. Seaward of Hutchison Bay, a large subbottom depression within sequence III in interpreted as a Late Wisconsinan fluviatile channel. According to our seismic interpretation, the Tuk Phase morainal and glaciofluvial deposits existing onland on the Tuktoyaktuk Peninsula, previously assigned to the Early Wisconsinan, would be of Late Wisconsinan age.


2002 ◽  
Vol 58 (2) ◽  
pp. 182-188 ◽  
Author(s):  
Lee C. Nordt ◽  
Thomas W. Boutton ◽  
John S. Jacob ◽  
Rolfe D. Mandel

AbstractA continuous record of organic carbon δ13C from a buried soil sequence in south-central Texas demonstrates: 1) strong coupling between marine and adjacent continental ecosystems in the late Pleistocene as a result of glacial meltwater entering the Gulf of Mexico and 2) ecosystem decoupling in the Holocene associated with a reduction of meltwater and a shift in global circulation patterns. In the late Pleistocene, reduction in C4 plant productivity correlates with two well-documented glacial meltwater pulses (∼15,000 and 12,000 14C yr B.P.), indicating a cooler-than-present adjacent continental environment. Increased C4 production between 11,000 and 10,000 14C yr B.P. suggests that the Younger Dryas was a warm interval responding to the diversion of glacial meltwater away from the Mississippi River. With waning meltwater flow, C4 productivity generally increased throughout the Holocene, culminating in peak warm intervals at ∼5000 and 2000 14C yr B.P. Shifts in the abundances of C3–C4 plants through the late Quaternary show no correlation to ecophysiological responses to atmospheric CO2 concentration.


2000 ◽  
Vol 54 (2) ◽  
pp. 264-274 ◽  
Author(s):  
Rebecca Teed

Pittsburg Basin, in south-central Illinois, contains a sediment record extending from the present back to the end of the late Illinoian glaciation, when central Illinois was covered with Picea/Pinus forest. During the last interglaciation, a temperate deciduous forest more diverse than Holocene Quercus/Carya forest replaced the Illinoian late-glacial boreal forest. Prairie pollen types and the charcoal/pollen ratio, indicating fire frequency, temporarily increased. Then forest, with high Juniperus percentages, became dominant once more, as the charcoal/pollen ratio dropped. After the last interglaciation, the charcoal/pollen ratio increased again and prairie and wetland surrounded Pittsburg Basin through the entire Wisconsinan glacial age. The area was still prairie in late Wisconsinan time, but with some Picea and Pinus. During the Holocene, the region has been a mixture of prairie and Quercus/Carya forest. During the last interglaciation, Pittsburg Basin was surrounded by vegetation different from that surrounding it during the present interglaciation. Rather than indicating substantial differences in climate between analogous phases of different glacial/interglacial cycles, this variation may be due to changes in fire frequency, which could be caused by small changes in climate, human activity, or differences in soil.


1980 ◽  
Vol 17 (11) ◽  
pp. 1462-1479 ◽  
Author(s):  
C. M. Tucker ◽  
S. B. McCann

Morphogenetic mapping of surficial deposits and analysis of infrequent multiple-unit exposures of drift in the Burin Peninsula and on St. Pierre and Miquelon provide evidence of the following sequence of late Quaternary events in the south-central coastal region of Newfoundland. (1) Overall glaciation by Newfoundland-centred ice (pre-Wisconsinan or, possibly, Early Wisconsinan in age), represented by a few occurrences of weathered till. (2) Overall glaciation by Newfoundland-centred ice (Early Wisconsinan), widely represented throughout the peninsula. (3) Marine overlap in the southwest of the peninsula and on St. Pierre and Miquelon (Mid-Wisconsinan). (4) Partial glaciation by ice from an offshore source to the southeast (late Mid-Wisconsinan), represented by onshore-directed striae and a well-developed former ice-marginal position in the lower peninsula. (5) Limited glaciation by Newfoundland-centred ice of the northern part of the area (Late Wisconsinan); the former ice margin is a well-defined feature across the Gisborne basin and small separate ice caps existed along the central spine of the upper peninsula. In developing the chronology for these events, the occurrence of marine deposits, containing Foraminifera of proposed Mid-Wisconsinan age, between two till units at Dantzic Cove in the southwest of the Burin Peninsula is important.


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