58 



PLEISTOCENE OF INDIANA AND MICHIGAN- 

 DRAINAGE. 

 LAKES. 



Numerous small lakes in the northern part of Indiana occupy depressions in the drift surface. 

 The largest, Turkey or Wawasee in Kosciusko County, has an area of only 5.66 square miles. 

 Few cover more than 1 square mile. The greatest depth, 121 feet, is found in Tippecanoe Lake 

 in Kosciusko County, but depths of 50 or more feet are found in many others. In the north- 

 west part of the State several shallow lakes are shut in between dune belts or beaches of Lake 

 Michigan and those of its predecessor, Lake Chicago. Numerous shallow ponds and lagoons lie 

 in the alluvial bottoms of the large rivers in the southwestern part of the State. In Dubois 

 County, near Jasper and Ireland, some conspicuous though shallow lakes, having areas of several 

 hundred acres each, stand in the line of preglacial valleys that have been only partly filled by 

 drift deposits. So far as known these are the only lakes in the State that antedate the Wisconsin 

 ice invasion. They are nearly filled by muck and aquatic vegetation and have recently been 

 greatly reduced in area by artificial drainage. 



The number of lakes and ponds in the State represented on the county maps in Baskin, 

 Forster & Co.'s State atlas is 683, of which 156 are in the alluvial bottoms and are transitory. 

 Some of those in the depressions of the glacial drift are nearly filled by vegetal growth and some 

 have been drained to a marshy condition by .artificial ditches. There remain probably less 

 than 400 which are too deep to be drained. The following table, obtained in large part from 

 the report by Blatchley and Ashley on the lakes and marl deposits of Indiana, 1 gives a list of 

 the more important lakes with their areas, altitudes, and depths: 



of Indiana having an area of 1 square mile or more. 



i Partly in Cook County, 111. 



6 Determined by barometer. 



MICHIGAN. 



In the southern peninsula of Michigan lakes are present in every county except three at the 

 head of Saginaw Bay; they are scarce, however, in several other counties in the plain southwest 

 of this bay and in the plain bordering Lakes Erie, St. Clair, and the southern part of Lake Huron. 

 They range in area from a few acres to 31 square miles, the largest being Houghton Lake, in Ros- 

 common County. The number is not known, for in some of the northern counties the best maps 

 yet published represent only a part of them. Many land-survey plats show only those crossed 

 by section or quarter-section lines and give measurements of only a few of those crossed ; conse- 

 quently the outline and extent of few are correctly set forth. The inaccuracies of the land-survey 

 plats have been repeated in county atlases and other maps. 



The lakes nearly all occupy depressions in the surface of the glacial deposits, some of them 

 being in the moraiues and others in the outwash aprons. Many in the latter areas are without 



i Twenty-fifth Ann. Rept. Dept. Geology and Nat. Res. Indiana, pp. 31-321, 1901. 



