USE OF LITHOLOGIC AND GAMMA LOGS TO DEFINE THE AREAL EXTENT OF A CLAY CONFINING UNIT OVERLYING A GLACIAL-DRIFT AQUIFER, MONTGOMERY COUNTY, NEW YORK.
C. M. Ryan,
G. R. Wall, and D. W. Hanchar (U.S. Geological Survey, 425 Jordan Rd., Troy NY 12180).
The hydrologic framework of a shallow glacial-drift aquifer Sprout Brook, Montgomery County, NY, was investigated by lithologic and gamma logging of a network of 13 monitoring wells. The work was completed as part of the Hudson River Basin National Water-Quality Assesment program to characterize ground-water quality beneath an agricultural area. The study area covers about 1 square mile of valley-bottom farmlands and is bounded by a till-mantled upland to the south and east and by the Canajoharie Creek to the north and west.
The clay confining unit, which is organic rich and about 0.5 feet thick, is exposed at the base of the Canajoharie Creek bank; it is overlain by 5 or more feet of generally unsaturated alluvium and underlain by the local glacial-drift aquifer. Lithologic and gamma logs indicate that the clay unit was penetrated in 9 of the 13 wells and is laterally continuous over much of the study area. Water-level data from the monitor well network indicate that the clay unit confines the underlying aquifer.
Abstract published in: Geological Society of America 1994. Abstracts with Programs: 26(3), page A70.
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