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Lineaments and fracture traces, Decatur County, Indiana

Open-File Report 82-918

Indiana Department of Natuarl Resources, Decatur County
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Abstract

Lineanents and fracture traces have been mapped throughout Decatur County, Indiana. These lineaments and fracture traces may indicate that solution enlarged vertical fractures in the limestone and dolonite aquifers underlie most of the county. The use of lineament and fracture-trace maps in selecting bedrock-drilling sites results in a significant increase in the number of usable sites. Bedrock wells drilled on or near mapped lineaments and fracture traces have a higher average yield than veils drilled into interfracture areas.  

Parts of Decatur County and several adjacent counties are economically restricted by inadequate water supplies. The Greensburg Municipal Water Works, supplying 35 percent of the county's population, obtains 25 percent of its water from six wells in Greensburg. The remaining 75 percent is pumped from the Flat Rock River. This water is piped 8.25 miles and lifted 183 feet to the treatment station. Although the Flatrock River has adequate flow to supply Greensburg's water needs, a ground-water supply can probably be developed nearer the treatment plant.

Pleistocene till covers most of the nearly horizontal bedrock. Although averaging about 50 feet thick, this unconsolidated unit does not seem to inhibit the mapping of lineaments and fracture traces. Bedrock is middle Paleozoic limestone, dolomite, and shale. Two sequences of limestone and dolomite, separated by a thin shale unit, constitute the principal aquifer. The extremely variable well yields from this aquifer indicate that the bedrock permeability is also variable.

Well placement is important in a fractured bedrock terrane, as fractures are a principal source of water to the well. Here, the most productive bedrock wells are at the mapped intersection of two or more fracture traces or lineaments and at the lowest local altitude. Use of a fracture-trace map will not guarantee a sufficient supply of ground water but will reduce the chance of drilling an inadequate well.

Study Area

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Lineaments and fracture traces, Decatur County, Indiana
Series title:
Open-File Report
Series number:
82-918
Year Published:
1983
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Indianapolis, IN
Contributing office(s):
Indiana Water Science Center
Description:
iv, 1 map ;74 x 70 cm., folded in envelope 31 x 24 cm. +1 pamphlet (21 p. ill., maps ; 28 cm.)
First page:
1
Last page:
18
Country:
United States
State:
Indiana
County:
Decatur
Online Only (Y/N):
N
Additional Online Files (Y/N):
N