280 PLEISTOCENE OF INDIANA AND MICHIGAN. 



Lake Maumee except in Lenawee County from the vicinity of Adrian southward. The reces- 

 sion of the ice from this moraine permitted the lake to extend northward to the Imlay outlet. 

 That this moraine may mark a readvance of the ice border at least along part of its course is 

 suggested (1) by the strength of the Maumee beach just outside the moraine near Findlay, Ohio, 

 which seems to demand a greater expanse of water than would lie in the narrow space between 

 the moraine and the beach; and (2) by the somewhat greater breadth of the lobe in the Maumee 

 basin as compared with that which formed the weak ridges between this moraine and the Fort 

 Wayne. (See pp. 168-170.) This broadening of the lobe brings the moraine very close to the 

 neighboring outlying ridges on the periphery of the basin, though in the axis it falls some ' 

 distance short. 



The Defiance moraine runs northeastward from the Ohio-Michigan line past Adrian, 

 Tecumseh, Saline, Ypsilanti, Northville, and Amy to Clinton River a few miles east of Pontiac. 

 It has a double crest and is more or less distinctly separated into two members, with inter- 

 vening till plain and gravel plain, for a few miles in the vicinity of Ann Arbor. This has led to 

 the introduction of the terms "outer Defiance ridge" and "inner Defiance ridge" in the revised 

 edition of the Ann Arbor folio and in the Detroit f oho. The outer Defiance ridge is the "middle " 

 moraine of the first edition of the Ann Arbor folio and the "Northville" moraine of the report 

 on Wayne County, Mich., by W. H. Sherzer, published by the Michigan Geological Survey. 



North from Clinton River the Defiance moraine is hi places banked against an earlier 

 moraine and in places separated from it by a narrow glacial drainage channel. It can be traced 

 as far as Belle River a few miles west of Imlay, beyond which point its continuation is uncertain. 

 Probably, however, it constitutes the outer part of a morainic system that runs northwestward 

 from Imlay into a reentrant angle between the Huron-Erie and the Saginaw lobes north of 

 Lapeer. If it does this, it is probably represented in the Saginaw basin by the Portland moraine 

 and perhaps by one or two other members of the system of slender moraines between the 

 Charlotte morainic system and the Port Huron morainic system. 



TOPOGRAPHY. 



The moraine rises from about 800 feet above sea level in the vicinity of the Ohio-Michigan 

 State line to 1,000 feet on the highest points in northeastern Oakland, northwestern Macomb, 

 and eastern Lapeer counties. In all these counties portions of it rise but little above 900 feet, so 

 that the general rise in the Michigan part is but little more than 100 feet. 



Near the State line of Ohio and Michigan the moraine changes from a very smooth water- 

 laid ridge to a gently undulating land-laid moraine. In places two or more ridges are recogniz- 

 able, but as a rule the crest line is single. At Adrian two ridges of about equal strength are 

 present, but between Adrian and Ypsilanti wherever two ridges are present the outer or western 

 is much stronger than the inner or eastern. Portions of the inner ridge in the vicinity of Ypsi- 

 lanti are below the level of Lake Maumee, and in southern Washtenaw County its crest almost 

 coincides with the highest beach of Lake Maumee. From the State line northeastward to 

 Clinton River the surface of the ridge is gently undulating and is characterized in places by 

 numerous basins, especially hi the Ann Arbor quadrangle west of Ypsilanti. From Clinton 

 River northward to southern Lapeer County large kames 75 to 100 feet or more hi height are 

 distributed along the moraine and stand in striking contrast with the gently undulating portion 

 farther south. 



STRUCTURE OF THE DRIFT. 



Along much of its course the moraine is clayey, though many of its small knolls are com- 

 posed in part of sand or gravel, and gravel is present hi large amounts in the kames north of 

 Clinton River. The moraine is in places coated with a sandy deposit due probably to flooded 

 conditions of the country immediately outside the moraine, for the ice was banked against a 

 slope which gathered waters from higher land to the west as well as from the melting of the ice. 

 These sandy deposits are conspicuous in the vicinity of Saline River in southern Washtenaw 

 County and northeastward from there to Ypsilanti. There is also considerable sand in the 

 vicinity of the State line on both the Ohio and the Michigan sides. 



