27 Quaternary Geology (Posters)

Tuesday, 19 April 2016
8:00 AM - 12:00 PM
Illinois Ballroom AB

SURFICIAL GEOLOGIC MAP OF THE WAVERLY 7.5-MINUTE QUADRANGLE, WESTERN KENTUCKY

Paper number: 27-8
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

The Kentucky Geological Survey is currently publishing STATEMAP-funded maps for western Kentucky through the KGS Geologic Map series. The Waverly 7.5-minute quadrangle is located in the lower Ohio River Valley, and is characterized by low-relief Pennsylvanian bedrock upland areas separated by broad alluvial valleys. The Ohio River basin served as an outlet for glacial meltwater and outwash during late Pleistocene glaciations. Rapid accumulation of outwash in the main Ohio River Valley blocked the mouths of tributaries, causing the impoundment of water and deposition of lacustrine sediments in the tributary valleys. These lacustrine deposits are overlain by Holocene floodplain deposits and have an interfingering relationship with loess near the base of the adjacent uplands. The loess was primarily derived from valley-bottom outwash surfaces in the Ohio River Valley, from which fine-grained sediments were removed by deflation and deposited on the adjacent upland areas.   A transect of cores were drilled along the profile of a hillslope to determine the contact relationship between upland loess deposits and alluvium and lacustrine deposits in the valley. The hillslope stratigraphy along the profile was complex and not uniform. The Peoria Loess and interglacial Sangamon paleosol are preserved in all but one of the cores. The Wisconsinan Roxana Silt is preserved beneath the Peoria Loess and above the Sangamon paleosol along the crest of the profile, but was eroded from sideslopes. The Sangamon paleosol was eroded, or never developed, from the bottom of the lowest elevated profile, which is characterized by alternating zones of dark grayish brown silt loam and yellowish brown silt. These alternating zones extend throughout the tributary valleys, and represent alluvial floodplain deposits and overlie lacustrine deposits in the main, deeper tributary valleys.   Bedrock contours were constructed in the tributary valleys using depth-to-bedrock data from oil and gas wells, coal boreholes, water wells, and Kentucky Transportation Cabinet geotechnical data on file at KGS. The bedrock contour model shows relatively steep valley walls with relatively flat valley floors in the subsurface.

Geological Society of America Abstracts with Programs. Vol. 48, No. 5

doi: 10.1130/abs/2016NC-275465

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