566 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



to extensive marshes. It is probable that the ice sheet had a discharge 

 for its waters down this creek, and the marshes and lowland tracts may 

 represent the channels occupied by the glacial waters. 



Black Fork Valley, from the point where it touches this moraine (south 

 of Shiloh) southeastward, contains numerous knolls, which give it an 

 appearance somewhat similar to the valley of Jerome Fork just described. 

 It, however, soon enters the main morainic system of the Scioto lobe, and 

 these knolls may, perhaps, form a portion of the inner member of that 

 system. It is probable that the ice sheet had a line of discharge down this 

 valley while forming the Wabash moraine, but it was not sufficiently strong 

 to clear the valley of its drift knolls and form conspicuous terraces. 



There was found along the Scioto Valley no decisive evidence of 

 vigorous drainage from this morainic series. Gravel and sand are exceed- 

 ingly rare, and what little silt there is in this outer-border district may be 

 independent of the moraine. The lack of evidence of drainage from this 

 portion of the ice margin is difficult to explain, especially since no barrier 

 appears to have existed along the course of the Scioto below the moraine 

 which could have checked the drainage. As previously noted, there are 

 extensive prairies on the eastern slope of this basin. They present a plane 

 surface and are covered with a black soil, but the soil is apparently till to 

 which carbonaceous matter has been added. Furthermore, they are not 

 level, there being an eastward rise of 100 to 150 feet from the axis of the 

 basin to the east border of the prairies. 



ST. MARYS OR FORT WAYNE MORAINE. 



This moraine was given the name St. Marys by Gilbert from its relation 

 to the St. Marys River, whose course it governs for about 60 miles. But as 

 the town St. Marys, Ohio, is on an earlier moraine, the name has led to some 

 confusion. In consequence of this, the name Fort Wayne, taken from the 

 most prominent city on the moraine, is supplementing the old name. Gilbert 

 recognized and named the moraine at the time he made a survey of western 

 Ohio in 1869 and 1870. It is, therefore, one of the earliest recognized 

 moraines on this continent.' It was Gilbert's conception, however, that the 



' The result of Gilbert's investigations in nortiiwestern Ohio appear in two places: First, in the 

 American Journal of Science for May, 1871, where a brief account only is given; second, in Vol. I 

 of the reports of the Ohio Geological Survey, which was published in 1873, and which contains a 

 somewhat detailed account of the region. 



