Mesozoic and Ccenozoic Geology and Palwontology. 335 



flowed the barrier or dividing ridge on the south, and swept over Ohio, 

 Indiana, Illinois, western Kentuckj', Tennessee and Mississippi, it 

 transported the material that constitutes the drift deposits of these 

 States, and which extends in the Mississippi valle}- as far as the Gulf 

 of Mexico. The rush of water was adequate to transport and distribute 

 the finer material, and the shore ice was sufficient to transport the 

 bowlders and larger masses, and distribute them as far soutli as they 

 occur. 



The lake deposits on the hills and mountains near the shores of 

 Lake Superior, occur 600 feet above the present level of the lake, or 

 high enough to overflow all the States to the south. The ancient soil 

 beneath the drift affords evidence that the climate was not materially 

 different from the climate of to-day. The land and fresh-water shells 

 found at different elevations in the drift, and the oft recurring 

 timber transported and buried at all heights within it, show nothing 

 that indicates a change of climate from the time preceding the drift 

 through all its various stages. The ancient beaches prove the differ- 

 ent elevations of the lakes, and teach us of long periods of time 

 required for the pebbles and bowlders to be made, that now form these 

 terraces, where they are preserved, and constitute so considerable a 

 part of the drift that was swept southwardly when the lakes overflowed 

 their barriers and carried them away. 



The drift is then not only of Post-pliocene age, but much of it dates 

 back through all Tertiary time, and some of it is, probably, much 

 older. But that part of it containing the Mammoth, Mastodon, Dico- 

 tyles, Castoroides, and other mammals, with aboriginal man, belongs 

 to the most recent or Post-pliocene era. 



The eastern end of Lake Ontario is near a volcanic region, and 

 within the range of the Appalachian system, where there have been 

 important local elevations and depressions, as heretofore shown, by the 

 sinking and rising of the coast from New York to Hudson's bay. The 

 disturbance and elevation has been sufliicient to throw the lakes back 

 over the State of New York, and high up on the hills to the north, as 

 shown l\y the numerous terraces, beaches and lacustrine deposits. 

 This great lake ma}^ never have united with the grand body of water 

 which is now represented on a smaller scale by Lake Superior, and 

 again the}' may have been united at some period, and disunited at 

 others. But all the phenomena presented in this region is to be 

 accounted for b}' the presence of these lakes at various altitudes. 



Lake Superior is in a volcanic region, and near the western end of 



