CLEVELAND MORAINE. 647 



OUTER BORDER PHENOMENA. 



The terraces and gravel plains associated with this morainic system are 

 all that will here be treated, the other drift features having alread}' been 

 considered. The discussion begins at the west and proceeds eastward. 



On the Cuyahoga no well-defined terraces were observed. There was 

 no doubt a discharge from this valley westward into Lake Maumee, near 

 the south border of the moraine. 



In the Grrand River Valley the plain south of the moraine has some 

 silt and some assorted material at surface, but the slig'ht exposures which 

 occur show the drift to be principally till, probably a ground moraine of 

 the same age as moraines farther south. 



On Pymatuning Creek, a tributary of the Shenango, there is a well- 

 defined moraine-headed terrace, consisting of a pitted gravel plain extending 

 from the moraine southward to Kinsman, a distance of 2 miles, below which 

 it is nearly free from pits. These small basins occupy an acre, more or less, 

 each, and have very abrupt, wall-like borders. The majority of them appear 

 to be filled up considerably with peat, but are still depressed from 5 to 10 

 feet, or even more, below the bordering gravel plain. 



On Shenango River no moraine-headed terrace was discovered, but 

 much assorted material lies along it below the moraine, and the stream in 

 this vicinity may now be occupying its glacial flood plain. 



On Crooked Creek, near Hai-tstown, are pits and small lakes bordered 

 by nearly level topped gravel deposits, which lead southward into a smooth- 

 surfaced plain. This stream seems to be flowing near the level of the 

 glacial flood plain for several miles below its source. 



In the Conneaut Valley there is an extensive marsh, leading- from 

 Conneaut Lake along its outlet nearly to French Creek. This is, perhaps, a 

 glacial flood plain, for the moraine, crossing the valley at the north end of 

 the lake, rises but little above the marsh. The lake bottom itself is a great 

 pit in this marsh at the point of connection with the naoraine. On the 

 southeast border of the lake there is a bench about 50 feet high, having a 

 few feet of till at surface and gravel below, which was probably formed 

 before the ice sheet made its last advance. Remnants of a terrace-like 

 bench, which may be its continuation, occur along the borders of the 

 marsh between Conneaut Lake and French Creek. They are, in soine 

 cases at least, not covered with till. 



