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J.D. Treworgy

Publications and source records attributed to J.D. Treworgy.

4 recordsLinked to original sources
USGS2010

Paradigms and proboscideans in the southern Great Lakes region, USA

Thirteen new chronometric dates for Illinois proboscideans are considered in relation to well-dated pollen records from northeastern and central Illinois. These dates span an interval from 21,228 to 12,944 cal BP. When compared to pollen spectra, it is evident that Mammut americanum inhabited spruce (Picea) and black ash (Fraxinus nigra) forest during the B??lling-Aller??d (14,700-12,900 cal BP) and early Younger Dryas (12,900-11,650 cal BP) chronozones. Both Mammuthus jeffersonii and Mammuthus primigenius inhabited spruce dominated open-woodland during the Oldest Dryas chronozone, while M.??primigenius persisted in a forest of predominantly black ash during the Aller??d chronozone. A newly discovered specimen from Lincoln, IL, clarifies the taxonomic distinction between M. primigenius and M.??jeffersonii. Hitherto, a paradigm of proboscidean succession during the full- to late-glacial periods was based on the vegetation succession of steppe tundra-like vegetation to spruce forest to spruce-deciduous forest. The presumed proboscidean succession was that of cold, dry steppe-adapted M. primigenius succeeded by more mesic-tolerant M. jeffersonii that in turn was succeeded by the wet forest-adapted M.??americanum. Reported data do not support this view and indicate a need for re-evaluation of assumptions of proboscidean ecology and history, e.g., the environmental tolerances and habits of M.??primigenius in regions south of 55??N, and its dynamic relationship with other proboscidean taxa. ?? 2009 Elsevier Ltd and INQUA.

Quaternary International↗
USGS2007

Mammoth (Mammuthus sp.) excavation on a college campus in Western Illinois, USA

The discovery of the remains of a mammoth, Mammuthus sp., on the Principia College campus in Elsah, Illinois, has allowed for careful excavation by students over several years. The mammoth is relatively well preserved in late Wisconsin Peoria Silt on the top of the bluffs of the Mississippi River. The mammoth was buried by loess, perhaps as a result of persistent dust storms, approximately 17 500 14C years ago. This age estimate is based on the mammoth's stratigraphic position within the Peoria Silt and is loosely supported by an AMS radiocarbon age on poorly preserved collagen from tooth dentine (???17 810??4300 14C years [CAMS #104172]). Over one hundred bones or bone pieces have been excavated to-date. The skull, containing the tusks and maxillary teeth, is complete and in close proximity to associated postcranial remains, indicating that the mammoth died where it was found. The size and characteristics of skeletal elements have allowed us to determine that this was a mature male of about 41 years of age. Taxonomic attribution-either to Mammuthus primigenius or Mammuthus jeffersonii-is pending, based on the outcome of thorough analysis once the skull with dentition has been prepared from enclosing matrix. ?? 2006 Elsevier Ltd and INQUA.

Quaternary International↗
USGS1999

Depositional facies and sequence stratigraphy of a Lower Carboniferous bryozoan-crinoidal carbonate ramp in the Illinois Basin, mid-continent USA

The Lower Carboniferous Fort Payne and Ullin Formations in the Illinois Basin form the transgressive and highstand systems tracts that were deposited in a carbonate ramp setting. During deposition of the Ullin Limestone, biotic communities dominated by fenestrate bryozoans and echinoderms (primarily crinoids) proliferated, possibly in response to global tectonic, biological, and oceanographic events that affected bathymetry and nutrient supply. The Fort Payne Formation consists of a dark grey-brown, siliceous and argillaceous lime mudstone in the lower part (transgressive systems tract) and a very fine-grained wackestone to packstone with rare mud mounds in the upper part (early highstand), and was deposited in an outer ramp to basinal environment. During deposition of the lower Ullin Limestone (mostly early highstand), bryozoan-crinoidal build-ups accreted both laterally and vertically into several relatively large carbonate banks, which were partly surrounded by siliceous Fort Payne sea. Bryozoans (primarily fenestrates) were especially prevalent during the late stage of bank development and formed mud-free bioherms up to 120 m thick. In places, carbonate mud mounds also formed during the early stage of bank deposition. Bioherm development declined during deposition of the upper Ullin Limestone (late highstand), and a broad, storm-dominated carbonate ramp was established that became the site for widespread deposition of bryozoan-crinoidal sandwaves. Gradual shallowing led to ooid formation at the end of Ullin deposition. This sequence was terminated by a relative rise in sea level that resulted in deposition of the transgressive facies of the lower part of the overlying Salem Limestone. The depositional style and the nature of skeletal material of the Fort Payne and Ullin Formations are similar to those of cool-water carbonates. A deep-water setting along with upwelling of cool, nutrient-rich oceanic waters may have been responsible for the proliferation of bryozoans and crinoids at this time. The deep-water setting and abundant nutrient supply also may have restricted the formation of ooids and proliferation of shallow-water calcareous organisms.

Geological Society Special Publication↗