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The geologic framework of southern Lake Michigan

Journal of Great Lakes Research

By:
,

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Abstract

The bathymetry is controlled by the underlying bedrock. Bedrock comprises Silurian dolomite and Devonian limestone and shale. Quaternary sediment, 10 to 40 m thick, overlies bedrock. From Waukegan, Illinois, south to Indiana Harbor, the bottom is floored by till, sand, pebbles, and cobbvles. The lake floor is erosional or nondepositional where till or gravel-cobble pavement is exposed. In contrast, north of Waukegan and east of Indiana Harbor, fine sand covers much of the bottom and grades offshore to muddy sand. The complex surficial bottom sediment distribution between Waukegan and Michigan City, Indiana, could be mapped in detail only where sidescan sonar mosaics are available. Sand, important for protecting the substrate from erosion and for maintaining beaches, is not abundant throughout much of the area. -from Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The geologic framework of southern Lake Michigan
Series title:
Journal of Great Lakes Research
Volume
20
Issue:
1
Year Published:
1994
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
44
Last page:
60
Number of Pages:
17