New Map of the Surficial Geology of Southwestern Ohio

Brockman, C. Scott, Richard R. Pavey, Gregory A. Schumacher, Douglas L. Shrake, E. Mac Swinford, and Kim E. Vorbau
Ohio Division of Geological Survey, Columbus, OH

A map depicting the surficial geology of the Ohio portion of the Cincinnati and Falmouth 1:100,000-scale quadrangles has been produced by the Ohio Department of Natural Resources, Division of Geological Survey. Surficial Deposits were mapped at 1:24,000 scale for 33 quadrangles, compiled digitally, and converted into a full-color, print-on-demand, 1:100,000-scale, surficial-geology map which includes Hamilton and Clermont Counties and portions of Brown, Butler, and Warren Counties. Polygon areas were assigned a stack-unit designation that depicts the thickness and stratigraphic sequence of lithologic units such as till, gravel, sand, silt, and clay from the surface down to and including the uppermost buried-bedrock unit. Data sources include field mapping, county soil surveys, Ohio Department of Transportation and Ohio EPA boring logs, engineering logs, water-well logs, theses, and published and unpublished reports.

The map reveals regional trends including the limits of massive sand and gravel deposits used as a source for aggregate and ground water, the extent and surprising thinness of Pre-Illinoian, Illinioian, and Wisconsinan-age glacial drift, and the wide and diverse distribution of lacustrine sediments. Lacustrine silt and clay deposits, where exposed at the surface, can be significant landslide geohazards and are specifically color-coded on the map. Bedrock directly beneath the surficial deposits is characterized by limestone and shale content. Shale-rich bedrock units also can be significant landslide hazards, particularly where exposed on steep slopes.

Mapping was partially funded by the U.S. Geological Survey National Cooperative Geologic Mapping Program, STATEMAP component and will benefit environmental scientists, engineers, land planners, and researchers.

AAPG Search and Discovery Article #90031©2004 AAPG Eastern Section Meeting, Columbus, Ohio, October 3-5, 2004