Mesozoic and Cenozoic Geology and Paleontology. 23k 
_. flowed the barrier or dividing ridge on the south, and swept over Ohio, 
Indiana, Illinois, western Kentucky, Tennessee and Mississippi, it 
transported the material that constitutes the drift deposits of these 
States, and which extends in the Mississippi valley as far as the Gulf 
of Mexico. The rushof 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 south 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 sufficient to throw the lakes back 
over the State of New York, and high up on the hills to the north, as 
shown by the numerous terraces, beaches and lacustrine deposits. 
This great lake may never have united with the grand body of water 
which is now represented on a smaller scale by Lake Superior, and 
again they may have been united at some period, and disunited at 
others. But all the phenomena presented in this region is to be 
accounted for by the presence of these lakes at various altitudes. 
Lake Superior is in a volcanic region, and near the western end of 
