288 PLEISTOCENE OF INDIANA AND MICHIGAN. 



Sherzer's Rawsonville bowlder belt enters Wayne County north of Livonia and runs southwest, 

 passing 2 miles west of Livonia, 2 miles east of Plymouth, and 2 miles east of Denton, and 

 comes down to Huron River at Bellville. It turns west up the river and after passing Raw- 

 sonville turns toward the southwest but has not yet been traced more than 3 or 4 miles into 

 Washtenaw County. The course and topographic relations of this belt suggest that it is in 

 some sense a continuation of the Birmingham moraine. 



Sherzer's Scofield bowlder belt enters Wayne County northeast of Livonia, passes a mile 

 east of Livonia and Wayne, and crosses Huron River north of Waltz station. Here it turns 

 southwest and passes out of Monroe County west of Ottawa Lake. From the north line of 

 Wayne County this belt descends about 60 feet to Huron River, showing a much greater varia- 

 tion in altitude than is found in any beach in this area. In its course southwest from Huron 

 River it passes Scofield and Maybee in Monroe County and is buried under the heavy sand belt 

 a mile southeast of Ida. According to Sherzer, its presumed continuation emerges from under 

 the sand belt in sec. 28, Summerfield Township, and winds across the southeast corner of Lena- 

 wee County into Ohio. On this course it rises from about 625 feet at Huron River to over 

 700 feet near the west line of Monroe County. This belt may continue to Sylvania, Ohio, and 

 be represented by a low till ridge which runs southwest from that place and controls drainage. 



The part of this belt north of Huron River was observed by the writer some years ago and 

 was regarded as a southward continuation of a moraine then called the Toledo moraine. 1 



A third belt, called by Sherzer the Grosse Isle bowlder belt, runs along the shore of Lake 

 Erie back of the marshes. The part between Monroe and the mouth of Detroit River is regarded 

 by Sherzer as a continuation of a moraine that crosses Grosse Isle. Its position in this part 

 may mark a halting place of the margin of the Lake Erie lobe, but its presumed continuation 

 runs southwest from Monroe, rising more than 100 feet to a point a few miles beyond the Ohio- 

 Michigan State line. Such a course seems unnatural for a marginal moraine or for any equiva- 

 lent of such a moraine of either the Huron or the Erie ice lobes. The medial axis of the Erie 

 lobe at the time of the Defiance moraine passed about through Toledo, and the Grosse Isle 

 bowlder belt passes only 12 miles northwest of Toledo in a course nearly parallel with the axis. 

 These discrepancies suggest either that this bowlder belt is not the equivalent of a terminal 

 moraine, or else that the parts separated by the heavy sand belt have not been rightly connected. 



These bowlder belts show certain characters and relations that led Mr. Leverett and the writer 

 to regard them at first as possible shore lines. The bowlders lie on till and in many places in 

 front of a low bluff or elevation, from the edge of which a more or less extensive and irregular 

 area of fine sand extends westward. Such an arrangement suggests a sandy beach with a 

 bowlder pavement before it. But this combination of features is not everywhere present, and 

 the wide vertical variation of the principal belts seems to preclude the idea of their being shore 

 lines, especially in this area, where all the clearly identified beaches are substantially horizontal. 



It is a singular fact that the northern part of each belt is so related to topography that it 

 would seem to be a normal extension from the northeast of some one of the water-laid moraines, 

 while (if the assumed connections are accepted) the southern part of each changes its direction 

 and trend to an upslope course, which is abnormal for a marginal moraine. 



In some respects the southern parts of the belts bear a slight resemblance to the transverse 

 ridges of Sanilac County (p. 266). But another possible explanation may be nearer the truth, 

 though it has not yet been fully developed and may apply only to the Grosse Isle belt. 



At the maximum of the ice extension the Erie and Huron ice lobes were intimately united, 

 forming substantially one solid lobe covering the lowland between the two basins. It is 

 probable, however, that even at the maximum there was a slight depression or crease along 

 the line of junction between them. As the ice sheet retreated in the basins of Lakes Erie and 

 Huron and from the high ground south of Georgian Bay the tendency of the two ice lobes to 

 separate and become distinct bodies became more and more pronounced. In his work on the 

 glacial deposits of the southwestern peninsula of Ontario it has been found by the present 

 writer that, although the highland south of Georgian Bay was completely overtopped during 



1 Equivalent to the Imlay and Goodland moraines described on pp. 263-285. 



