| 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 |
| Genre: | Article |
| ProdID: | 70017145 |
| Citation Author: | Foster, D. S.; Folger, D. W. |
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| Citation End Page: | 60 |
| Citation Issue: | 1 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Great Lakes Research |
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| Citation Number Of Pages: | 17 |
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| Citation Search Results Text: | The geologic framework of southern Lake Michigan; 1994; Article; Journal; Journal of Great Lakes Research; Foster, D. S.; Folger, D. W. |
| Citation Start Page: | 44 |
| Citation Volume: | 20 |
| Citation Year: | 1994 |
| Type: | citation/reference |
| Text: | The geologic framework of southern Lake Michigan; 1994; Article; Journal; Journal of Great Lakes Research; Foster, D. S.; Folger, D. W. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
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