Odom, J. Edgar
M.S. (Master of Science)
Department of Geology
Geology--Illinois--Du Page County
The elevation of the bedrock surface and the thickness of the glacial drift in a fire square mile area in southwestern Dupage County, Illinois, were mapped in detail from data obtained by means of a hammer seismograph. Bedrock deaths and drift thicknesses determined by seismic methods showed a correlation coefficient of +0.97 with information from wells and sewer test-borings used as a control group. Silurian dolomite is known to compose the bedrock in the area. The topography of the bedrock surface and the present-day topographic surface are quite similar. The drainage system on the bedrock surface appears to be joint controlled. No major karst features were mapped in the area. Variations in seismic velocities within the glacial drift indicate that the drift is composed of a sandy, gravelly layer overlain by a silty clay till. A sons of saturation may have influenced the drift velocities and may also be related to the "weathered" tone. A ten foot contour interval was considered ae the most reliable interval for mapping the bedrock surface. The 95% confidence interval placed the seismic control points within 3.68 feet above and 0.12 feet below the bedrock surface established by well and boring control points. The hammer seismograph is considered a practical and economical means of obtaining accurate depths to bedrock in areas of drift cover of lees than fifty feet.
Johnson, Donald O., "A geophysical investigation of the bedrock surface in southwestern DuPage County, Illinois" (1966). Graduate Research Theses & Dissertations. 343.
v, 59 pages
Northern Illinois University
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