43 



face of the slopes of the highlands of Ohio ; and, in some places, col- 

 lections of them are seen occupying areas of several acres, and num- 

 bering many thousands, all apparently having been brought here 

 together and from one locality. 



(4) At various points are found remarkable pits, conical depres- 

 sions in the superficial deposits, which have been attributed to icebergs 

 stranding and melting, dropping their loads of gravel and stone around 

 theii- resting-places. 



(5) The beds of clay and other transported materials mentioned 

 above are several hundred feet in thickness, extending from at least 

 one hundred feet below the present water-level in the lakes to points 

 five hundred feet or more above that level. 



(6) During the "glacial period" to which I have referred, the 

 whole countiy must have been relatively higher than at present, and 

 the drainage much more free ; for, during this epoch, the valleys of the 

 streams were excavated to a far greater dejjth than they are at 

 present. This is proven by the explorations which have been made 

 in all the country bordering Lake Erie in search of rock oil. The 

 borings made upon the Upper Ohio and its tributaries, as . well as 

 along the rivers emptying into Lake Erie, show that all these streams 

 flow above their ancient beds, — the Mahoning and Shenango, at their 

 junction, one hundred and fifty feet, the Cuyahoga at its mouth over 

 one hundred feet above the bottom of their rocky troughs. The valley 

 of the Mississippi at St. Louis and Dubuque, and the Missouri at and 

 above Council Bluffs, exhibit precisely similar phenomena, — deep 

 troughs excavated in the rock by the ancient representations of the 

 present streams, subsequently submerged and filled up with drift clay, 

 gravel, or loess ; these troughs having been but partially cleared of 

 these accumulations by the action of the rivers during what we call 

 the present epoch. 



(7) Along the margins of the great lakes are distinct lines of 

 ancient beaches, which show that in comparatively recent times the 

 water-level in these lakes was full one hundred feet higher than at 

 present. 



The facts enumerated above seem to justify us in the following in- 

 ferences in regard to the former history of this portion of our conti- 

 nent, (a) At a period corresponding with, if not in time, at least 

 in the chain of events, the glacial epoch of the Old World, tlie lake 

 region^ in common with all the northern portion of the American conti- 

 nent, was raised several thousand feet above the level of the sea. In 

 this period the fiords of the Atlantic (and probably Pacific) coasts 

 were excavated, as also the deep channels of drainage which, far 

 above their bottoms, are traversed by the Mississippi and its branches, 

 and indeed most of the streams of the lake country. 



