564 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



head, or north end of the gravel plain, is known as Ayer Flats. It is 

 crossed by the Northern Ohio Railroad, whose profile shows its altitude 

 to be 998 feet above tide, or about 425 feet above Lake Erie. There is 

 a gradual descent southward through Copley Marsh to the Tuscarawas 

 River, near New Portage, the altitude of the outlet of Copley Marsh being 

 400 feet above Lake Erie. The gravel on Ayer Flats is rather fine, having 

 few pebbles exceeding an inch in diameter, but is composed of well-assorted 

 material. There are numerous basins in the plain, depressed 4 to 8 feet 

 below its surface, each an acre or more in extent. The deeper ones have 

 about the level of the north end of Copley Marsh. This marsh is covered 

 with so heavy a deposit of peat and muck that the ditches which drain it 

 (2 to 4 feet in depth) do not reach the bottom. As stated on a previous 

 page, a boring near the southern end of the marsh penetrates about 400 

 feet of drift, mainly silt. This is the only deep boring yet made in the 

 valley. It is probable that the silt extends northward beneath the gravel of 

 Ayer Flats and the till of the moraine that lies just north of these flats, 

 connecting with the silt deposits along the Cuyahoga. 



In Sharon Township, Medina County, a small tributary of the 

 Tuscarawas emerges from the moraine. Its valley contains gravel dejDosits 

 below the point of emergence, but their surface is not so level as tei'race 

 deposits usually are, and it seems probable that they were an incident of 

 the retreat of the ice sheet rather than an outwash from the moraine. 



In the valley of the river Styx there is a broad marshy plain a mile or 

 more in width, which heads in the moraine near the village of River Styx. 

 It is underlain by a mucky clay and appears to have but little gravel on 

 its surface. In crossing the valley, 4 miles below River Styx village, low 

 gravelly ridges and knolls were observed on both its eastern and western 

 borders, but they have not the level surface of the ordinary terrace, and 

 are probably deposits incident to the retreat of the ice sheet. 



In Chippewa Valley, from Seville southward beyond Sterling, there 

 are low sandy knolls 3 to 5 feet and occasionally 10 feet in height, which, 

 together with a slight deposit of sandy clay, rest upon the silt deposits 

 with which the valley was filled. The knolls may possibly have been 

 formed by the agency of wind. The material was probably contributed 

 as a quiet outwash from the moraine. 



On Killbuck Creek there is an open plain extending up to the Fort 



