Recurring deposition of eolian sand during the Late Quaternary in northeastern Colorado
- U.S. Geological Survey, Denver, CO (United States)
Three superposed units of late Quaternary eolian sand separated by buried soils and (or) clayey pond sediment are present along the southeast side of the South Platte River valley in northeastern Colorado. The oldest unit consists of at least 1.5 m of pale-brown sheet sand in which an A/Bw/C soil profile is developed; the solum is typically 45-55 cm thick. At Sterling, the oldest unit is overlain by organic-rich pond sediment that yielded a radiocarbon age of 9,010[+-]100 B.P. The middle unit consists of at least 0.4-2 m of pale-brown, massive to horizontally stratified sand. An A/C soil profile, with a light brownish-gray A horizon 13-25 cm thick, marks the upper limit of the unit. Radiocarbon ages from the Sterling site indicate that the middle unit was deposited between 9,010[+-]100 B.P., the age of underlying pond sediment, and 2,860[+-]60 B.P., the age of organic matter from the horizon at the top of the unit. The youngest unit consists of 0.5-8 m of pale-brown dune sand in which a faint A horizon (Valent series), typically 3-10 cm thick, has developed. Data from the cutbanks near Brush indicate that this unit was deposited about 1 ka or later. Organic matter from a buried A horizon beneath the youngest unit yielded a radiocarbon age of 1,380[+-]90 B.P. More importantly, however, the dated paleosol contained Plains Woodland ceramics, and Upper Republican ceramics were present just above the paleosol. The Plains Woodland culture was present in eastern Colorado between about 1.9 and 1 ka, and the Upper Republican culture between about 1 and 0.7 ka. The dune topography and soil development in the youngest unit near Brush are characteristic of large tracts of dune sand in northeastern Colorado, which suggests that the most recent episode of eolian activity may be younger than 1 ka.
- OSTI ID:
- 5806420
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COLORADO
SEDIMENTARY BASINS
DEPOSITION
AGE ESTIMATION
ARCHAEOLOGICAL SITES
CARBON 14
DUNES
ISOTOPE DATING
QUATERNARY PERIOD
SAND
THICKNESS
WIND
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON ISOTOPES
CENOZOIC ERA
DEVELOPED COUNTRIES
DIMENSIONS
EVEN-EVEN NUCLEI
GEOLOGIC AGES
GEOLOGIC STRUCTURES
ISOTOPES
LIGHT NUCLEI
NORTH AMERICA
NUCLEI
RADIOISOTOPES
USA
YEARS LIVING RADIOISOTOPES
580000* - Geosciences