274 PLEISTOCENE OF INDIANA AND MICHIGAN. 



the moraine northwest of Fostoria, where there are kames and much very stony ground with 

 knobs and basins. 



The surface of this deposit is quite uneven, especially in its western part, which contains 

 a number of basins. Its eastern part is composed mainly of fine gravel and sand and its alti- 

 tude along the front of the moraine is 850 to 860 feet. It appears to have been deposited in 

 the border of a shallow lake. 



SILVERWOOD OUTWASH APRON. 



From the front of the Mayville moraine a plain of sandy and gravelly outwash stretches 

 1J miles south, reaching nearly to Silverwood and extending a mile or two farther south on 

 each side of that place. Its composition grows finer toward its outer edge. For 3 or 4 miles 

 the Otisville moraine appears to be completely buried under this deposit, the upper edge of 

 which has an altitude of about 860 feet. 



This outwash apron has some peculiar features. South and southeast of Silverwood its 

 front has a sort of digitate form, several narrow, finger-like ridges of sandy gravel, some of 

 them a third to a half mile long, project south-southwest in straight lines over the flat, smooth 

 clay plain. These ridges are 10 or 15 feet high and have some resemblance to the lobations 

 seen on the fronts of some deltas but are too narrow and too precisely parallel for such an 

 origin to be probable. It has also been suggested that they may have been formed in channels 

 in a dead ice mass which covered the plain. As yet no explanation offered seems altogether 

 satisfactory. The deposit as a whole, however, appears to have been laid down in a shallow 

 lake. 



DRAINAGE SOUTH OF IMLAY CHANNEL. 



HOLLY CHANNEL AND LAPEER GLACIAL LAKE. 



The headward part of the Holly channel is in Lapeer County near Hadley, and it seems 

 quite certain that central Lapeer County was occupied by a relatively small glacial lake which 

 lay chiefly in Lapeer, Mayfield, and Attica townships and partly in Oregon and Elba townships, 

 and which discharged southwestward through the Holly glacial river. This lake, known as 

 the Lapeer glacial lake, received drainage directly from the ice around the interlobate angle 

 and drainage from the ice border for some distance south on the east side of the high land, the 

 latter probably entering through the channel running north and northwest from Dryden. 



ELBA CHANNEL. 



The Elba channel is nearly as large as the Holly and was apparently but little lower. 

 The Lapeer glacial lake was shallow when it discharged through the Holly channel, so it is 

 doubtful whether it remained in existence with the lower outlet. There are two or three pas- 

 sages through the Hadley ridge (Portland moraine) which might have allowed the waters to 

 go westward to the Elba channel. One of these* is southwest by way of Bronson Lake in 

 Oregon Township, and another through Nipissing Lake in Elba Township. The even spread of 

 the gravel fan at the end of the Oregon esker seems to suggest still but shallow water for its 

 deposition, or at any rate water with too little current to effect the formation of the fan. 

 The drainage of this area went first past Atlas to the Lookingglass channel and afterward to 

 the Davison glacial lake. 



LTJM CHANNEL. 



The Lum channel is remarkable. It is only a fragment, extending northwest from about 

 2 miles north of Imlay to Flint River in northern Deerfield Township, parallel to the part of the 

 Imlay channel between Mill Creek and Rich Township. This channel is a mile and in some parts 

 more than a mile wide — two or three times as wide as the narrow part of the Imlay channel. Its 

 banks, especially in its southern and middle parts, stand 70 to 90 feet above its floor; toward the 

 northwest they are lower. . From Mill Creek to Kings Mills the eastern bank is a high, rugged 

 moraine, so steep along its front facing the channel that it seems certain that it was undercut by 

 a river. 



