DRAINAGE SYSTEMS AND THE GLACIAL PERIOD. 203 



extending from Georgian Bay to the vicinity of To- 

 ronto. 



With a fair degree of probability, the basin of Lake 

 Superior is supposed by Professor Newberry to have been 

 joined to that of Lake Michigan by some passage, now 

 buried, considerably to the west of the Strait of Mackinac, 

 and thence to have had an outlet southward from the 

 vicinity of Chicago directly into the Mississippi Eiver. 

 Of this there is considerable evidence furnished by deeply 

 buried channels which have been penetrated by borings 

 in various places in Kankakee, Livingston, and McLean 

 Counties, Illinois; but the whole area extending from 

 Lake Michigan to the Mississippi is so deeply covered 

 with glacial debris that the surface of the country gives 

 no satisfactory indication of the exact lines of preglacial 

 drainage. 



Some of the most remarkable instances of ancient 

 river channels buried by the glacial deposits have been 

 brought to light in southwestern Ohio, where there has 

 been great activity in boring for gas and oil. At St. 

 Paris, Champaign County, for example, in a locality where 

 the surface of the rock near by was known to be not far 

 below the general level, a boring was begun and continued 

 to a depth of more than five hundred feet without reach- 

 ing rock, or passing out of glacial debris. 



Many years ago Professor Newberry collected suffi- 

 cient facts to show that pretty generally the ancient bed 

 of the Ohio River was as much as 150 feet below that 

 over which it now flows. During a continental elevation 

 the erosion had proceeded to that extent, and then the 

 channel had been silted up during the Glacial period with 

 the abundant material carried down by the streams from 

 the glaciated area. One of the evidences of the pregla- 

 cial depth of the channel of the Ohio was brought to 

 light at Cincinnati, where "gravel and sand have been 

 found to extend to a depth of over one hundred feet below 



