Date of Award
Master of Science
Geological and Environmental Sciences
Dr. Ronald Chase
Dr. Gerry Clarkson
Dr. Richard Passero
Dr. William Sauck
Masters Thesis-Open Access
Fractures were recorded and measured at seven southwest Michigan glacial till locations to identify geometry and spacing. Strong preferred orientations were shown at azimuths of 110° and 140° for two sites, and at azimuths of 85°, 110°, and 135°, and at 44° and 167° for two sites. Several sites had numerous oblique fractures.
Thirty-eight azimuthal Wenner arrays and four Schlumberger surveys show apparent resistivities vary widely with depth of penetration and material composition. Eleven percent of azimuthal surveys show an elliptical data array coinciding with preferred orientation of an adjacent fracture set. The relationship between azimuthal survey and fractures is due to the paradox of anisotropy.
Successful correlations were not always accomplished due to anthromorphic structures such as buried cables or sewer systems. Dry conditions during part of the work decreased electrode contact and increased apparent resistivity values, and the paradox of anistropy did not apply when overburden was greater than roughly five times the "a" spacing used.
Freed, Ralph L., "A Fracture Analysis of Glacial Tills in Southwest Michigan" (1993). Masters Theses. 786.