scholarly journals Late-Glacial and Postglacial Vegetation and Climate of Jackson Hole and the Pinyon Peak Highlands, Wyoming

1987 ◽  
Vol 11 ◽  
pp. 55-59
Author(s):  
Cathy Barnosky
Keyword(s):  
Environmental Changes ◽  
Late Quaternary ◽  
Late Glacial ◽  
Ice Age ◽  
Plant Migration ◽  
Critical Gap ◽  
Long Term Stability ◽  
The North ◽  
Jackson Hole ◽  
Central Rocky Mountains

The objective of this study has been to describe the late-Quaternary vegetation of the Jackson Hole region and vicinity in order to clarify the nature and composition of ice-age communities, the rate and direction of plant migration during the recession of glaciers from the region, and the long-term stability of communities in the Park to environmental changes in the postglacial period. This information is necessary to assess the sensitivity of the Park's communities to environmental change and fill a critical gap in our understanding of the vegetational, climatic, and glacial history of the north-central Rocky Mountains as a whole.

Chrysophyte microfossils record marked responses to recent environmental changes in high- and mid-arctic lakes

2001 ◽  
Vol 79 (6) ◽  
pp. 747-752 ◽  
Author(s):  
Alexander P Wolfe ◽  
Bianca B Perren
Keyword(s):  
Environmental Changes ◽  
Arctic Lakes ◽  
Ice Age ◽  
Algal Community ◽  
North Coast ◽  
Baffin Island ◽  
Lake Ecosystems ◽  
The North ◽  
Ecological Changes ◽  
Community Shifts

Rapid stratigraphic changes are recorded in recent assemblages of subfossil Chrysophyceae from the sediments of two highly contrasted arctic lakes, one situated in the polar desert of west-central Ellesmere Island, and the other on eastern Baffin Island in the mid-Arctic climatic zone. In Sawtooth Lake on the Fosheim Peninsula, concentrations of chrysophycean stomatocysts increase dramatically in sediments deposited since AD 1920. Only trace abundances of stomatocysts are encountered in older sediments. In Kekerturnak Lake, on the north coast of Cumberland Peninsula, scales of Mallomonas spp., previously absent from the sediment record, appear suddenly in the upper 5.5 cm of sediment and subsequently become ubiquitous in the top 1.0 cm. These results corroborate diatom stratigraphic data from other sites in the Canadian Arctic Archipelago, together suggesting that unprecedented ecological changes are presently occurring across this vast region. In all likelihood, these abrupt algal community shifts reflect the response of arctic lake ecosystems to well-documented climate warming since the Little Ice Age, with the implications that recent rates of environmental change are unprecedented in the context of the Holocene.Key words: Paleolimnology, arctic lakes, Chrysophyceae, stomatocysts, Mallomonas.

scholarly journals Key Environmental Factors Controlling Planktonic Foraminiferal and Pteropod Community’s Response to Late Quaternary Hydroclimate Changes in the South Aegean Sea (Eastern Mediterranean)

2020 ◽  
Vol 8 (9) ◽  
pp. 709
Author(s):  
Christina Giamali ◽  
George Kontakiotis ◽  
Efterpi Koskeridou ◽  
Chryssanthi Ioakim ◽  
Assimina Antonarakou
Keyword(s):  
Environmental Factors ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Eastern Mediterranean ◽  
Planktonic Foraminifera ◽  
Explanatory Power ◽  
Principal Component ◽  
Aegean Sea ◽  
Late Glacial ◽  
The South

A multidisciplinary study was conducted in order to investigate the environmental factors affecting the planktonic foraminiferal and pteropod communities of the south Aegean Sea. Aspects of the Late Quaternary paleoceanographic evolution were revealed by means of quantitative analyses of planktonic foraminiferal and pteropod assemblages (including multivariate statistical approach; principal component analysis (PCA)), the oxygen (δ18O) and carbon (δ13C) isotopic composition of planktonic foraminifera and related paleoceanographic (planktonic paleoclimatic curve (PPC), productivity (E-index), stratification (S-index), seasonality) indices, extracted by the gravity core KIM-2A derived from the submarine area between Kimolos and Sifnos islands. Focusing on the last ~21 calibrated thousands of years before present (ka BP), cold and eutrophicated conditions were identified during the Late Glacial period (21.1–15.7 ka BP) and were followed by warmer and wetter conditions during the deglaciation phase. The beginning of the Holocene was marked by a climatic amelioration and increased seasonality. The more pronounced environmental changes were identified during the deposition of the sapropel sublayers S1a (9.4–7.7 ka BP) and S1b (6.9–6.4 ka BP), with extremely warm and stratified conditions. Pteropod fauna during the sapropel deposition were recorded for the first time in the south Aegean Sea, suggesting arid conditions towards the end of S1a. Besides sea surface temperature (SST), which shows the highest explanatory power for the distribution of the analyzed fauna, water column stratification, primary productivity, and seasonality also control their communities during the Late Quaternary.

Holocene and latest Pleistocene fluctuations of Stutfield Glacier, Canadian Rockies

2001 ◽  
Vol 38 (8) ◽  
pp. 1141-1155 ◽  
Author(s):  
G D Osborn ◽  
B J Robinson ◽  
B H Luckman
Keyword(s):  
19Th Century ◽  
18Th Century ◽  
Late Glacial ◽  
Ice Age ◽  
Late 19Th Century ◽  
Canadian Rockies ◽  
The Holocene ◽  
The North ◽  
History Of ◽  
Glacier Advance

The Holocene and late glacial history of fluctuations of Stutfield Glacier are reconstructed using moraine stratigraphy, tephrochronology, and dendroglaciology. Stratigraphic sections in the lateral moraines contain tills from at least three glacier advances separated by volcanic tephras and paleosols. The oldest, pre-Mazama till is correlated with the Crowfoot Advance (dated elsewhere to be Younger Dryas equivalent). A Neoglacial till is found between the Mazama tephra and a paleosol developed on the Bridge River tephra. A log dating 2400 BP from the upper part of this till indicates that this glacier advance, correlated with the Peyto Advance, culminated shortly before deposition of the Bridge River tephra. Radiocarbon and tree-ring dates from overridden trees exposed in moraine sections indicate that the initial Cavell (Little Ice Age (LIA)) Advance overrode this paleosol and trees after A.D. 1271. Three subsequent phases of the Cavell Advance were dated by dendrochronology. The maximum glacier extent occurred in the mid-18th century, predating 1743 on the southern lateral, although ice still occupied and tilted a tree on the north lateral in 1758. Subsequent glacier advances occurred ca. 1800–1816 and in the late 19th century. The relative extent of the LIA advances at Stutfield differs from that of other major eastward flowing outlets of the Columbia Icefield, which have maxima in the mid–late 19th century. This is the first study from the Canadian Rockies to demonstrate that the large, morphologically simple, lateral moraines defining the LIA glacier limits are actually composite features, built up progressively (but discontinuously) over the Holocene and contain evidence of multiple Holocene- and Crowfoot-age glacier advances.

scholarly journals Late-Glacial and Postglacial Vegetation and Climate of Jackson Hole and the Pinyon Peak Highlands, Wyoming

1985 ◽  
Vol 9 ◽  
pp. 44-49
Author(s):  
Cathy Barnosky
Keyword(s):  
Rocky Mountains ◽  
National Park ◽  
Vegetation History ◽  
Late Quaternary ◽  
Late Glacial ◽  
Glacial Refugia ◽  
Northern Rocky Mountains ◽  
Jackson Hole ◽  
History Of ◽  
Vegetation And Climate

The late-Quaternary vegetation history of the northern Rocky Mountains has thus far been inferred largely from isolated records. These data suggest that conifer forests were established early in postglacial time and were little modified thereafter. The similarity of early postglacial vegetation to modern communities over broad areas gives rise to two hypotheses: (1) that glacial refugia were close to the ice margin, and (2) that vegetation soon colonized the deglaciated areas and has been only subtly affected by climatic perturbations since that time. It is the goal of this project to test these two hypotheses in the region of Grand Teton National Park.

scholarly journals Geochemical characteristics of the infilling of ground wedges at Puerto Deseado (Santa Cruz, Argentina): palaeoenvironmental and chronological implications

2018 ◽  
Vol 45 (2) ◽  
pp. 130 ◽  
Author(s):  
Giovanni Zanchetta ◽  
Adriano Ribolini ◽  
Matteo Ferrari ◽  
Monica Bini ◽  
Ilaria Isola ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Volcanic Glass ◽  
Late Glacial ◽  
Major Elements ◽  
Chemical Analyses ◽  
The North ◽  
Xrd Patterns ◽  
Bulk Chemistry ◽  
Deseado Massif ◽  
Glass Shards

Ground wedge structures of cryogenic origin are common in the Quaternary sediments along the coast of the Patagonia, and their formation is related to climatic cold events experienced by this area in the Late Quaternary. The infilling sediments of two wedges generations were analyzed in the area of Puerto Deseado. Bulk chemistry (major elements), X-ray diffraction (XRD), morphoscopic observations with Scanning Electronic Microscope (SEM) and chemical analyses of volcanic glass shards were undertaken to provide indications about infilling sediment provenience, along with chronological constraint for wedge formation. Bulk chemistry and XRD patterns indicate a significant SiO2-enriched composition of the sediment infilling compared to the most of the loess deposits of the North Argentina and the present day dust originated in Patagonia. This was interpreted as due to the nature of the bedrock present over the Deseado Massif. SEM morphoscopic characteristics of glass shards evidence typical aeolian reworking features, with impact structures and indented edges of the volcanic fragments. Chemical analyses of the glass shards indicate that they were probably generated by the H0 eruption (17,300-17,400 cal yr BP) of the Hudson volcano. Volcanological data indicate that H0 eruption dispersed toward NE, but volcanic glasses were available for reworking due to a WNW component in the western wind direction. Over the Deseado Massif structural high the glass shards mixed with sediments enriched in SiO2, and were eventually deflated further to SE reaching the present coastal area and infilling the frost cracks. The age of the glass shards (17,300-17,400 cal yr BP) and that of the sandy layer affected by cryogenic structures (14,670±750 yr BP) well constrain to the Late Glacial both wedge generations.

scholarly journals LGM and Late Glacial glacier advances in the Cordillera Real and Cochabamba (Bolivia) deduced from <sup>10</sup>Be surface exposure dating

2007 ◽  
Vol 3 (4) ◽  
pp. 623-635 ◽  
Author(s):  
R. Zech ◽  
Ch. Kull ◽  
P. W. Kubik ◽  
H. Veit
Keyword(s):  
North Atlantic ◽  
Late Quaternary ◽  
Late Glacial ◽  
Tropical Andes ◽  
Surface Exposure Dating ◽  
Exposure Dating ◽  
The North ◽  
Innovative Tool ◽  
Cordillera Real ◽  
Exposure Ages

Abstract. Surface exposure dating (SED) is an innovative tool already being widely applied for moraine dating and for Late Quaternary glacier and climate reconstruction. Here we present exposure ages of 28 boulders from the Cordillera Real and the Cordillera Cochabamba, Bolivia. Our results indicate that the local Last Glacial Maximum (LGM) in the Eastern Cordilleras occurred at ~22–25 ka and was thus synchronous to the global temperature minimum. We were also able to date several Late Glacial moraines to ~11–13 ka, which likely document lower temperatures and increased precipitation ("Coipasa" humid phase). Additionally, we recognize the existence of older Late Glacial moraines re-calculated to ~15 ka from published cosmogenic nuclide data. Those may coincide with the cold Heinrich 1 event in the North Atlantic region and the pronounced "Tauca" humid phase. We conclude that (i) exposure ages in the tropical Andes may have been overestimated so far due to methodological uncertainties, and (ii) although precipitation plays an important role for glacier mass balances in the tropical Andes, it becomes the dominant forcing for glaciation only in the drier and thus more precipitation-sensitive regions farther west and south.

A submerged late-Quaternary deposit at Roddans Port on the north-east coast of Ireland

1965 ◽  
Vol 249 (758) ◽  
pp. 221-255 ◽  
Keyword(s):  
Local Development ◽  
Late Quaternary ◽  
Algal Species ◽  
Late Glacial ◽  
Red Clay ◽  
Quaternary Deposit ◽  
Radiocarbon Dates ◽  
North East ◽  
The North ◽  
Pollen Analyses

Recent coastal erosion has cut into the filling of a former inter-drumlin lake and exposed an excellent sequence of Late-glacial deposits. These have been investigated by pollen analyses, identification of seeds, Mollusca, ostracods, and Algae; by stratigraphic studies and by radiocarbon dating. The coincidence of all this evidence strongly confirms that the greater part of the depositional sequence embraces the north-west European Late-glacial stages of the Older and Younger Dryas or Salix herbacea clays, with the intervening milder Allerod oscillation. This sequence is overlain by a small thickness of Post-glacial peat. The Late- and Post-glacial filling is shown to be sandwiched between deposits laid down during two phases of marine submergence; the earlier transgression is represented by a red marine clay which had a widespread occurrence on the Co. Down coast, and the later transgression is represented by the local development of the Postglacial raised beach. The pollen analyses from the close sampling of the organic Allerød phase muds have yielded unusually detailed data on vegetational conditions in the Late-glacial period. The radiocarbon dates, while fully confirming the age attribution, have not enough precision to give a close measure of the duration of the Allerød phase. The pollen evidence on vegetation and climate is augmented and clarified by identifications of seeds, shells, ostracods and Algae. The ostracods confirm the marine character of the early red clay, and freshwater shells were found in the overlying Allerød mud. The algal species from the Late-glacial layers have been compared with recent algal floras from Ireland, and with those found in Late- and Inter-glacial sediments elsewhere. The most notable feature is the prominence of species representative of a base-rich habitat.

scholarly journals Holocene Environmental Variability in Southern Greenland Inferred from Lake Sediments

2002 ◽  
Vol 58 (2) ◽  
pp. 149-159 ◽  
Author(s):  
Michael R. Kaplan ◽  
Alexander P. Wolfe ◽  
Gifford H. Miller
Keyword(s):  
Environmental Changes ◽  
Environmental Variability ◽  
North Atlantic Ocean ◽  
Regional Climate ◽  
High Amplitude ◽  
Ice Age ◽  
Lake Productivity ◽  
The North ◽  
Ocean Region ◽  
Future Warming

AbstractSediments from Qipisarqo Lake provide a continuous Holocene paleoenvironmental record from southern Greenland. Following deglaciation and glacio-isostatic emergence of the basin from the sea ∼9100 cal yr B.P., proxies of lake paleoproductivity, including biogenic silica and organic matter, increased markedly until 6000 cal yr B.P. and thereafter remained stable over the ensuing warm three millennia. Subsequent decreases in these proxies, most dramatically between 3000 and 2000 cal yr B.P., show the lake's responses to initial Neoglacial cooling. Intervals of ameliorated limnological conditions occurred between 1300 and 900 and between 500 and 280 cal yr B.P., briefly interrupting the decreasing trend in productivity that culminated in the Little Ice Age. Increased lake productivity during the latter half of the 20th century, which reflects the limnological response to circum-arctic warming, still has not reached peak Holocene values. The Neoglacial climate of the last 2000 yr includes the most rapid high-amplitude environmental changes of the past nine millennia. The Norse thus migrated around the North Atlantic Ocean region in the most environmentally unstable period since deglaciation. Lacustrine sediment records provide a context with which to consider future environmental changes in the Labrador Sea region. In particular, any future warming will be superposed on a regional climate system that is currently exhibiting highly unstable behavior at submillennial timescales.

scholarly journals A Lacustrine Revolution: Adaptive Shifts in the Late Glacial of South Central Europe

2021 ◽  
Vol 29 ◽  
Author(s):  
Michael Jochim
Keyword(s):  
Settlement Patterns ◽  
Environmental Changes ◽  
Late Glacial ◽  
Ice Age ◽  
Human Populations ◽  
South Central ◽  
The Alps ◽  
Last Ice Age ◽  
Adaptive Shifts ◽  
New Habitats

The environmental changes in Europe at the end of the last ice age had profound effects on human populations. One of these changes, the development of numerous lakes in the region north of the Alps, created new habitats and niches that were rapidly exploited, with significant effects on many aspects of behavior. The record of environmental and archaeological changes in southern Germany and Switzerland are examined with an emphasis on some of the implications of the resulting change in settlement patterns.

A Late-Quaternary Pollen Record from Ka‘au Crater, O‘ahu, Hawai‘i

1999 ◽  
Vol 52 (1) ◽  
pp. 115-128 ◽  
Author(s):  
Sara Hotchkiss ◽  
James O. Juvik
Keyword(s):  
Last Glacial Maximum ◽  
Late Quaternary ◽  
Late Glacial ◽  
Glacial Maximum ◽  
Pollen Record ◽  
Forest Species ◽  
Subtropical Anticyclone ◽  
Last Glacial ◽  
Mesic Forest ◽  
The North

A pollen record from Ka‘au Crater, O‘ahu, Hawai‘i contains evidence for changes in vegetation and climate since about 28,000 14C yr B.P. Zone 1 (ca. 28,100–ca. 22,800 14C yr B.P.) has pollen of dry to mesic forest species, including Pipturus-type, Dodonaea viscosa, Acacia koa, Chenopodium oahuense, Claoxylon sandwicense, Myrsine, and Metrosideros-type. In zone 2 (ca. 22,800–ca. 16,200 14C yr B.P.) Myrsine and Coprosma increase, with herbs, fern allies, and Grammitidaceae suggesting open canopies. Zone 3 (ca. 16,200–ca. 9700 14C yr B.P.) has pollen of wet forest species, including Freycinetia arborea, abundant Pritchardia, and Metrosideros-type. Zone 4 (ca. 9700–ca. 7000 14C yr B.P.) is similar, with less Pritchardia and more Metrosideros-type.Climate reconstruction was based on modern climatic ranges of flowering plants and an index derived from abundance of pollen in surface samples. Both methods agree on a qualitative reconstruction, although the ages are poorly constrained: 28,000–25,000 14C yr B.P. cool and dry; 25,000–23,000 14C yr B.P. dry and warmer; 23,000–20,000 14C yr B.P. moderately dry with declining temperature; 20,000–16,000 14C yr B.P. moderately dry and cool; 16,000–9000 14C yr B.P. warm and wet; 9000–7000 14C yr B.P. warm and possibly drier. Lower precipitation at Ka‘au Crater during the late glacial period and last glacial maximum is consistent with the interpretation that the North Pacific subtropical anticyclone was south of its present position. The pollen-derived temperature index yields an estimate of 3°–5°C temperature depression during the last glacial maximum.

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