Title of Oral/Poster Presentation

Late Pleistocene Piedmont Records in the Grand Staircase Region, Southern Utah

Class

Article

College

College of Science

Faculty Mentor

Tammy Rittenour

Presentation Type

Poster Presentation

Abstract

Research focuses on the influence of climate and geomorphic processes on late Pleistocene landscape evolution of the Grand Staircase region of southern Utah, using piedmont deposits that blanket bedrock benches in the region as markers of past hillslope sediment supply and river incision. This study examines five headwater tributary catchments to the Colorado River, with base level controlled by Grand Canyon. Tested hypotheses are that piedmont gravel deposition corresponds to either full-glacial conditions or the transition between glacial and interglacial conditions. Investigation and correlation of piedmont deposits is based on geomorphic analysis, and detailed outcrop and facies descriptions of the sedimentology, stratigraphy, and soil profile development. Age control is provided by optically stimulated luminescence (OSL) dating of representative deposits in each catchment. Preliminary results indicate that regionally extensive piedmont gravel deposition occurred primarily during marine isotope stage (MIS) 5c, MIS 5a and MIS 4. Minor deposits date to MIS 3. This suggests that late Pleistocene piedmont gravels were deposited during a time period when global (Lisiecki and Raymo, 2004) and regional (Winograd et al., 2006) isotope records suggest unsteady and rapidly varying conditions between wetter/cooler (MIS 5d and 5b, MIS 4) and drier/warmer (MIS 5a and 5c) climates following the last full interglacial conditions of MIS 5e. Piedmont and terrace deposits dating to the last glacial maximum (LGM, MIS 2) have not been found. Results suggest that the extensive piedmont gravels found across the Grand Staircase region of southern Utah formed due to enhanced bedrock erosion or release of stored hillslope sediment in response to unsteady climate change in late MIS 5 and MIS 4.

Location

The South Atrium

Start Date

4-12-2018 10:30 AM

End Date

4-12-2018 11:45 AM

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Apr 12th, 10:30 AM Apr 12th, 11:45 AM

Late Pleistocene Piedmont Records in the Grand Staircase Region, Southern Utah

The South Atrium

Research focuses on the influence of climate and geomorphic processes on late Pleistocene landscape evolution of the Grand Staircase region of southern Utah, using piedmont deposits that blanket bedrock benches in the region as markers of past hillslope sediment supply and river incision. This study examines five headwater tributary catchments to the Colorado River, with base level controlled by Grand Canyon. Tested hypotheses are that piedmont gravel deposition corresponds to either full-glacial conditions or the transition between glacial and interglacial conditions. Investigation and correlation of piedmont deposits is based on geomorphic analysis, and detailed outcrop and facies descriptions of the sedimentology, stratigraphy, and soil profile development. Age control is provided by optically stimulated luminescence (OSL) dating of representative deposits in each catchment. Preliminary results indicate that regionally extensive piedmont gravel deposition occurred primarily during marine isotope stage (MIS) 5c, MIS 5a and MIS 4. Minor deposits date to MIS 3. This suggests that late Pleistocene piedmont gravels were deposited during a time period when global (Lisiecki and Raymo, 2004) and regional (Winograd et al., 2006) isotope records suggest unsteady and rapidly varying conditions between wetter/cooler (MIS 5d and 5b, MIS 4) and drier/warmer (MIS 5a and 5c) climates following the last full interglacial conditions of MIS 5e. Piedmont and terrace deposits dating to the last glacial maximum (LGM, MIS 2) have not been found. Results suggest that the extensive piedmont gravels found across the Grand Staircase region of southern Utah formed due to enhanced bedrock erosion or release of stored hillslope sediment in response to unsteady climate change in late MIS 5 and MIS 4.