Bibliographic Citation
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| Title | Dune-dammed lakes of the Nebraska Sand Hills: Geologic setting and paleoclimatic implications |
| Creator/Author | Loope, D.B. ; Swinehart, J.B. (Univ. of Nebraska, Lincoln, NE (United States)) |
| Publication Date | 1992 Jan 01 |
| OSTI Identifier | OSTI ID: 5770639 |
| Report Number(s) | CONF-921058-- |
| Other Number(s) | Journal ID: ISSN 0016-7592; CODEN: GAAPBC |
| Resource Type | Conference |
| Specific Type | Journal Article |
| Resource Relation | Journal Volume: 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992 |
| Subject | 58 GEOSCIENCES; NEBRASKA; PALEOCLIMATOLOGY; CLIMATIC CHANGE; DRAINAGE; DUNES; FLOW BLOCKAGE; GEOLOGIC HISTORY; GLACIERS; GULF OF MEXICO; LAKES; MOISTURE; SEDIMENTS; WIND; ATLANTIC OCEAN; CARIBBEAN SEA; DEVELOPED COUNTRIES; NORTH AMERICA; PALEONTOLOGY; SEAS; SURFACE WATERS; USA |
| Description/Abstract | Within the western half of this grass-stabilized dunefield, about 1,000 interdune lakes are grouped into two clusters here named the Blue and Birdwood lake basins. In the lake basins, those parts of the valley not filled by dune sand are occupied by modern lakes and Holocene lake sediments. The Blue Creek dam is mounded transverse to flow; spill-over of the lake basin takes place over bedrock on the east side of the dam when lake level is 2 m higher than present. The permeability of dune sand prevents massive overflow, and thereby contributes to the integrity and longevity of the dam. Preserved lake sediments in the basin indicate that Blue Creek was obstructed prior to 13,000 yr BP, probably during glacial maximum (18,000 yr BP). Extensive peats dated at 1,500-1,000 yr BP lie directly on fluvial sand and gravel along the Calamus River, a stream that presently discharges a nearly constant 350 cfs. These sediments indicate blockage of streams also took place when linear dunes were active in the eastern Sand Hills in Late Holocene time. With the onset of an arid episode, dunes forming an interfluves curtail the severity of runoff events. As the regional water table drops, drainages go dry and dunes move uncontested into blocking positions. Although drainages of the eastern Sand Hills appear to have repeatedly broken through sand-blocked channels, the Blue and Birdwood lake basins are still blocked by Late Pleistocene dune dams. The repeated episodes of stream blockage and interbedded lake sediments and dune sands behind the extant dams record several strong fluctuations in Holocene climate. Recently proposed climatic models indicate that the northward flow of warm, moist air from the Gulf of Mexico is enhanced when the Gulf's surface temperature is low and the Bermuda high is intensified and in a western position. When the Bermuda high moves eastward, the core of the North American continent becomes desiccated. |
| Country of Publication | United States |
| Language | English |
| Format | Medium: X; Size: Pages: A180 |
| System Entry Date | 2008 Feb 07 |
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