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C. E. Schweger

Publications and source records attributed to C. E. Schweger.

5 recordsLinked to original sources
USGS2017

Late Pleistocene Vertebrates and Other Fossils from Epiguruk, Northwestern Alaska

Sediments exposed at Epiguruk, a large cutbank on the Kobuk River about 170 km inland from Kotzebue Sound, record multiple episodes of glacial-age alluviation followed by interstadial downcutting and formation of paleosols. Vertebrate remains from Epiguruk include mammoth, bison, caribou, an equid, a canid, arctic ground squirrel, lemmings, and voles. Radiocarbon ages of bone validated by concordant ages of peat and wood span the interval between about 37,000 and 14,000 yr B.P. The late Pleistocene pollen record is dominated by Cyperaceae, with Artemisia, Salix, Betula, and Gramineae also generally abundant. The fossil record from Epiguruk indicates that the Kobuk River valley supported tundra vegetation with abundant riparian willows during middle and late Wisconsin time. Large herbivores were present during the height of late Wisconsin glaciation as well as during its waning stage and the preceding interstadial interval. The Kobuk River valley would have been a favorable refugium for plants, animals, and possibly humans throughout the last glaciation.

Quaternary Research↗
USGS1999

Neogene and Quaternary quantitative palynostratigraphy and paleoclimatology from sections in Yukon and adjacent Northwest Territories and Alaska

quantitative pollen and spore zonation for the Neogene and Quaternary of Yukon, western Northwest Territories and central and northern Alaska has been assembled from seven sections and one borehole. The palynological spectra from 163 samples from these sections were grouped and averaged within the groups to produce twenty-one composite spectra that depict the long-term pattern of vegetation change. The oldest record included in the study is estimated to be within the late Early Miocene (ca. 18.3 Ma) and the record extends to the late Quaternary. Pollen and spores are grouped and summed by environmental tolerances and physiognomy of the modern families and genera of plants to which they are related. Using these groups, pollen and spore ratios are drawn to track environmental parameters - temperature, forest canopy cover, and paludification of the study sites. Biostratigraphic and paleoecological patterns are explained in terms of known changes in global climate and the climatic effects of regional tectonics. Six assemblage zones and five subzones are proposed to describe the palynological succession.

Alaska, Northwest Territories, Yukon↗
USGS1997

An 18 million year record of vegetation and climate change in northwestern Canada and Alaska: Tectonic and global climatic correlates

We reconstruct long-term vegetation/paleoclimatic trends, spanning the last 18 million years, in Alaska. Yukon and far western Northwest Territories. Twenty-one average percentage spectra for pollen and spores are assembled from eight surface/subsurface sections. The sections are dated independently or by correlation. Pollen and spore ratios indicate the direction of change in vegetation and climatic parameters growing season temperature (T(est)), tree canopy density (C(est)) and paludification at study sites (P(est)). A global warm peak ca. 15 Ma is shown by the abundance of thermophilous taxa, including Fagus and Quercus. A temperature decline immediately following 15 Ma parallels climatic reconstructions based on marine oxygen isotopes. Subsequent declines correlate to the Messinian event and the onset of late Pliocene Pleistocene glaciation. After 7 Ma herbs and shrubs become more important elements of the palynological assemblages, suggesting a more continental, colder/drier climate. However, a late Pliocene warm interval is evident. Vegetation/climatic changes during the early to late Miocene show synchrony with, and are most economically attributable to, global events. After 7 Ma, vegetation/climate change is attributed primarily to latest Miocene-to-Pleistocene uplift of the Alaska Range and St. Elias Mrs. The continuing influence of global climatic patterns is shown in the late Pliocene warm interval, despite uplift to the south. The opening of the Bering Strait ca. 3 Ma may have moderated the climate in the study area.

Palaeogeography, Palaeoclimatology, Palaeoecology↗
USGS1991

Report of 1st discussion group: The last interglacial in high latitudes of the Northern Hemisphere: Terrestrial and marine evidence

The paleoclimatic informations preserved at some selected sites from high northern latitudes correlative with the last interglacial maximum of Isotopic Substage 5e have been compiled on a hemisphere scale. The mapped compilation reveals much warmer climate conditions on average than present in both terrestrial and marine environments, and indicates a northward shift of subpolar and boreal bioclimatic zones. The data also suggest that temperature and precipitation gradients were significantly different than those of the Holocene, with particularly efficient latitudinal and eastward transport of warm air masses. The paleoenvironmental and paleoclimate trends through the last interglacial sensu lato (Isotopic Stage 5) are more difficult to assess because the chronostratigraphical framework is poorly constrained. Nevertheless, the data suggest important regionalism in the climatostratigraphical trends. In particular, the large amplitude climatic cyclicity that characterizes the last interglacial of Europe is barely observed elsewhere. Moreover, by the end of the last interglacial (Isotopic Substage 5a), conditions slightly cooler than present are recorded in western Europe, while relatively warm conditions, similar to today, apparently prevailed in circumpolar regions adjacent to the North Atlantic despite the onset of ice growth. The last interglacial provides paleosynoptic situations, unlike those of the present, that may contribute to understanding interactions within the environmental system on a hemispheric scale. There is, however, an imperative need for uniformization of data sets and for more accurate chronological control on regional scales.

Quaternary International↗