LATEE. MORAINES OF LAKE MICHIGAN, SAGINAW, AND HURON-ERIE LOBES. 267 



At the bend of Mill Creek 2 miles northwest of Yale two ridges seem to start from the 

 same point. One, which is notable for its bowlders, runs west to the termination of the ridge 

 just mentioned, in sec. 7, Lynn Township. The other and stronger runs south for 6 miles and 

 then turns southwest on a nearly straight line toward Almont, dying out toward the south- 

 west in sec. 31, Mussey Township. Just north of. the southwest section of the ridge he shorter 

 fragments parallel with it and one longer fragment which seems to converge southwestward 

 with it. 



Other features, apparently of the same kind but smaller, he in Lapeer County. One runs 

 southwest from Brown City toward the Deanville kames and is probably related to them. 

 Another runs southwest through Burlington Township to the Imlay channel, a mile north of 

 North Branch. 



The origin of the transverse ridges can not be fully explained at present. It seems clear, 

 however, that they are related in some way to strong lines of drainage in or under the ice, and 

 are therefore in a certain sense analogous to eskers, although not of typical esker form. The 

 one that runs southwest from Melvin and the one which converges with it from the east seem 

 to have found their southwestward prolongation up the valley of Mill Creek through Goodland 

 Township and in a general way toward the interlobate angle, when that angle was acute and was 

 situated on the high ground of southern Lapeer County. The other large ridge points in a gen- 

 eral way toward the same place. It is conceived that these ridges were produced not by sub- 

 glacial streams but by streams whose positions were inherited from lines of drainage which led 

 to the interlobate angle when the ice front was in southern Lapeer County, and that the ridges 

 themselves were developed at a later time when the ice front had receded to the Imlay or the 

 next later moraine and had become relatively thin at the margin, so that the streams encoun- 

 tered dirty basal layers of the ice. 



TOPOGRAPHY. 

 ALTITUDE AND RELIEF. 



The moraines of this district do not show much variation in altitude, excepting in the 

 southern part of Tuscola County between Otter Lake and Kingston. When the ice front rested 

 on the high moraines at the south edge of Lapeer County the interlobate angle was acute and the 

 front hnes of the two lobes faced each other almost directly. At the time of the building of the 

 outer two moraines the ice front had dropped from its high position to the plain of central 

 Lapeer County and the acute angle had opened out and become nearly a right angle. At the 

 time of the building of the later moraines which bend around the north side of Lapeer County 

 the angle had changed to a curve, at first a semicircle but later more open, with a sweep of 20 

 to 26 miles. Though the area considered here is in a broad sense interlobate, at the particular 

 stages discussed true interlobate conditions of deposition did not exist, for there was no conflict 

 of opposing or converging ice. The front curved gradually from one lobe to the other around 

 a wide unoccupied area throughout wlhch normal conditions of marginal deposition prevailed. 

 At only one or two places did small local reentrants in the ice front cause a heaping of deposits 

 from two sides. This relation — a broad curve instead of a sharp angle — naturally led to the 

 making of moraines with more even crest altitudes than would otherwise have been built. 



In western Lapeer County the crests of the outer two moraines have altitudes 880 and 890 

 feet above sea level, only a few small areas reaching 900 feet; their relief is seldom more than 

 50 or 60 feet, with an average of 35 to 40 feet. In central Lapeer County these two moraines 

 are developed in much greater strength, some knolls rising to 960 feet, though the general 

 altitude is about 900 feet. From Flint River in Rich and Deerfielcl townships southeastward 

 to Imlay the altitude is mostly 900 to 950 feet. In many places the relief is 80 to 100 feet and 

 in two or three over 150 feet. The Otter Lake moraine rises to about 925 feet south of Otter 

 Lake and has a relief of 50 to 60 feet. 



The Mayville moraine between Otter Lake and Mayville forms the most extensive high 

 ground in the district, much of it rising above 900 feet and one hilltop a mile west of Mayville 



