No. 4.] CLAYPOLE — PRE-GLACIAL GEOGRAPHY. 191 



Now a river cannot excavate its bed below the bottom of the 

 valley or lake into which it flows, and as Lake Erie does not 

 much exceed 200 feet in depth, it follows of necessity that the 

 bottom of the channel of the Cuyahoga and the bottom of the 

 lake are nearly on the same level. It is impossible therefore to 

 doubt that at the time when this older Cuyahoga flowed along its 

 now buried channel the Erie valley had been excavated to its 

 full depth, and that whatever was the agent we cannot attribute 

 the erosion to the ice ol the glacial era, since both valley and 

 river equally belong to pre-glacial times. 



Another argument may also be founded on the facts above 

 given concerning the Cuyahoga. It is frequently affirmed that 

 enormous erosion occurred over the face of the country during 

 the ice age, and that, even if we grant the existence of an exca- 

 vation where Lake Erie now lies, yet that excavation must have 

 been deepened aud widened under the action of the continental 

 ice sheet. But no one will maintain that the ice deepened the 

 gorge of the Cuyahoga from Cleveland to Boston, fifteen miles 

 back from the lake, and it is equally impossible to maintain that 

 the Erie basin which lies at nearly the same level can have been 

 much deepened during the glacial era. The higher parts of the 

 country may have been somewhat worn down, and the basin of 

 the lake slightly eroded, but there is absolutely no evidence 

 proving any perceptible change in the outline and depth of the 

 Erie valley since early Quaternary days. 



Yet a third inference may be drawn from the relative condi- 

 tions of the Cuyahoga and the Erie Valley at the time now 

 under consideration. There is no reason to believe that the 

 river at Cleveland was much larger than now while it is abso- 

 lutely certain that it flowed at least 200 feet below its present 

 level, or nearly on the bottom of the present lake. We may 

 hence safely conclude that the lake had no existence, and that 

 the bed of 3 the Cuyahoga continued into the wide open vale of 

 Erie without meeting any such inland sea as that into which it 

 now falls, and emptied itself into some larger stream then flowing 

 eastward through the valley. 



The same was also in all probability true of the Rocky River, 

 and of other streams now tributary to the lake. For example : 

 " Borings at Toledo show that the old bed of the Maumee is at 

 least 140 feet below its present surface level." Geological Sur- 

 vey of Ohio, 1874, p. 15. The instances given are however 

 sufficient for our purpose, and we pass on. 



