GLACIAL LAKE WAEEEN. 395 



About 2 miles southwest of Watrousville the moraine falls 20 feet or more below the Warren 

 beach, and two finely formed gravelly spits run off toward the southeast. About 2 miles away 

 the beach reappears 3 miles north of Vassar on an island separated by a narrow passage from 

 another island which extends southward with declining altitude into the village. In the west- 

 ern part of the village the beach is finely developed as a heavy ridge of coarse gravel and pebbles 

 which hooks around a lagoon to the east. The water tower is on the crest of the spit. 



At Vassar the Warren beach turns east across the crest of the main moraine of the Port 

 Huron system and runs northeast along its outer face. In this stretch it is faint, for it was 

 formed in a long narrow bay which extended northeast nearly to Cass City, tapering and shal- 

 lowing northeastward. 



South of Cass River the region is very sandy, and the Warren beach has not been traced 

 continuously. The same conditions continue southwestward to Flint River. 



Saginaw and Gratiot counties. — West of Flint River the horizon of the Warren beach 

 passes out of the sand and enters a region of stony clay, a water-laid moraine. The Warren 

 beach appears in rather light form in Maple Grove and Chesaning townships, passing about a 

 mile south of Laytons Corners and 2 to 3 miles south of Chesaning. West of Shiawassee River 

 the country again becomes sandy and the beach is not definitely traceable. The same condi- 

 tions continue westward through Saginaw County into Gratiot County. The lowest part of the 

 divide between the Grand River channel and the watershed of Saginaw Bay is on the county 

 line. According to the profile of the projected Grand River and Saginaw deep waterway, the 

 divide stands 72 feet above Lake Huron, or about 653 feet above sea level. 



The whole vicinity of the divide is a region of wind-blown sand ridges and swampy lanes. 

 The beach representing Lake Warren is a somewhat indefinite belt of sand, carrying in places 

 low ridges of fine gravel, that runs along the southern margin of the sandy, swampy area west- 

 ward through northern Chapin and southern Elba townships, with an altitude of 675 to 6S5 feet. 

 The corresponding belt representing the shore on the north side was not fully traced, but it 

 was seen 1£ miles east of Ashley. These two lines thus converge into the head of the outlet 

 with a width of about 2 mdes on the railroad fine southeast of Ashley. (See fig. 1, p. 258.) 



A mile southeast of Ashley the railroad crosses a rather remarkable cat-tad swamp about 

 a mde wide and nearly 3 mdes long from northeast to southwest. It appears to have resulted 

 from the last erosion and deepening accomplished by the outlet river at the head of the Grand 

 River channel. The swamp formerly extended down Maple River, but this connection was cut 

 off by sediments brought by the river from the higher ground at the south and deposited on the 

 swampy floor. The upper Warren ridge is 20 to 25 feet above the lowest part of the pass and 

 the lower ridge is about 15 feet above it. The lowering of the lake by about 10 feet probably 

 measures the erosion on the divide during the time of Lake Warren. The divide is on the upper 

 edge of an eastward-sloping clay plain, but the westward gradient of the channel was then 

 very low. (See pp. 360-361.) 



Northward from the head of the outlet the plane of the Warren beach follows a broken, 

 sandy belt into the eastern edge of Gratiot County and passes a mde or two east of Wheeler. 

 In tins interval the beach appears in some places as a low, gravelly ridge. 



Isabella, Midland, and Gladwin counties. — From the Gratiot County fine the beach takes a 

 northwesterly course into the edge of Isabella County east of Mount Pleasant, and turns north- 

 east through Midland and Gladwin counties. The predominance of sand prevents continuous 

 tracing of the beach through this region, but fragments thought to belong to it have been seen 

 in some places. Like the other beaches it turns south in eastern Gladwin County to get across 

 the Port Huron morainic system and then goes northeastward through Bay, Arenac, and 

 Iosco counties. In eastern Gladwin its plane passes through an extensive sand plain and 

 swampy region, where it was not traced. 



Bay County and northward. — The Warren beach appears in a few places in Gibson Town- 

 ship, Bay County, as a distinct gravel ridge. It passes northward about half a mile west of 

 Bently and curves gradually through Adams Township, Arenac County, to the south bank of 

 Rifle River. In this stretch it is only occasionally seen as a gravel ridge, generally appearing 



