250 PLEISTOCENE OF INDIANA AND MICHIGAN. 



THREAD RIVER ESKER. 



A large and rather irregular esker about 5 miles long, known as the Thread River esker 

 runs southeast from Flint. Its south part lies half a mile or more south of the front of the St. 

 Johns moraine and was therefore formed in connection with the Fowler moraine. Thread River 

 flows in the west side of its trough for a mile or two. Its passage through the St. Johns mo- 

 raine in sec. 33, T. 7 N., R. 7 E., is typical, the esker being interrupted and terminated on 

 the north side of the break by two large kames. The large kettle hole in the south part of 

 Flint is probably related to the esker trough, although it shows no direct connection. 



This esker was made by a subglacial river flowing southeastward along the axis of the 

 Flint protrusion or lateral lobe. Near Flint the esker is worked extensively for gravel for the 

 manufacture of cement blocks and sand-lime bricks; it shows a percentage of gravel larger than 

 that of most eskers in this region. 



THETFORD ESKER. 



The Thetford esker, which runs south through sees. 5, 8, and 17 in Thetford Township, 

 in northern Genesee County, is a sharp-topped, well-formed ridge, apparently related to the 

 Owosso moraine. In the south part of sec. 8 it has a sharp jog to the east. Two or three small 

 kames stand east of its south end. 



MISCELLANEOUS SMALL ESKERS. 



There are in this district a few other eskers a mile or so in length and a considerable number 

 of shorter ones. One of the most notable lies east of Ovid. The trough which contains it 

 comes from the northeast. In sec. 6, Owosso Township, and sec. 12, Middlebury Township, 

 the trough contains a fine and conspicuous fragment of esker more than half a mile long. 

 Farther west, in sec. 12, Middlebury Township, it contains another esker about three-fourths of 

 a mile long, nearly parallel to the front of the Flint moraine. After cutting nearly through the 

 moraine, the trough runs for some distance nearly parallel with the Imlay channel but finally 

 enters it from the east, pointing downstream, as if influenced by the direction of flow of the 

 Imlay outlet river, though how this could have occurred is not clear. 



The east side of the large trough which runs southwest from Owosso through the Flint 

 moraine contains two fragments of eskers. A little farther south and across the Imlay channel 

 three esker-like gravel ridges cut through the St. Johns moraine, two of them running on to 

 the Fowler moraine, 2 miles to the south. A well-formed gravelly esker over half a mile long 

 runs southwest through the Flint moraine in sec. 31, Clayton Township, Genesee County. 



A small, low esker about a mile long runs southeast past the road corners a mile north of 

 Davison, in Genesee County. Several small eskers occur in relation to the expanded part of the 

 St. Johns moraine and also in relation to the Fowler moraine in southwestern Genesee County. 



In central Clinton County a number of kames are associated with the irregular moraines. 

 One situated 2 miles northwest of St. Johns is somewhat like an esker, being drawn out to a 

 length of over 2 miles toward the southwest, but is so broad and flat that it seems like a kame 



rather than an esker. 



GLACIAL DRAINAGE. 



GENERAL FEATURES. 



The drainage associated with the ice border presents considerable variety. During some 

 of the earlier positions of the ice in the western part of the district, the drainage flowed in rela- 

 tively small channels directly away from the front. At other times it collected in rivers of 

 greater or less size. 



The rivers which flowed along the front of the ice are of two types — those that gathered 

 their waters from the ice and land of the immediate vicinity or from areas not far away and 

 those that were the outlets of one or more of the greater glacial lakes. Most of the former 

 class have relatively small and shallow channels, indicating relatively small volume and short 

 duration. Those of the latter are generally much larger and more deeply intrenched, showing 



