436 
[Assembly 
barrier we do not doubt, but at present, we have too little accurate 
knowledge to point out its location, or the means by which it has been 
removed. 
The excavation of the basins of the great Lakes, is a subject still in- 
volved in obscurity, if we suppose the relative levels of land and water 
to have been always what they now are. The deepest of these are 
600 feet below the level of the ocean. The original excavation of the 
bed of Lake Ontario, was in the rocky strata, which have been removed 
to the depth of from 200, to nearly 400 feet below the level of the ocean. 
Subsequently this basin has been filled, or partially filled with alluvial 
materials. The shores where rocks are not visible, consist of clay, sand 
and gravel, possessing the same character on either side of the lake, 
and evidently the same deposit.* Whether this deposit ever extended 
entirely across the lake, or only to some distance from the present 
shores may be a matter of question. 
The great depth of the bed of Lake Ontario, proves beyond doubt, 
that it could not have been excavated whilst the present depth of wa- 
ter existed, even by the most powerful current. The occurrence of the 
tertiary of Champlain, proves that place to have been depressed at 
least 300 feet below its present elevation ; if that depression was com- 
municated westward, the former bed of Lake Ontario may have been 
laid nearly dry, by the waters having found a ready outlet to the ocean. 
If at this period all the waters of the great inland sea, passed in this 
direction, the bed may have been excavated. It would however, better 
account for this great depth, could we prove that its bed had been rais- 
ed, and after being excavated, again submerged. May not the depres- 
sion of the eastern portion of the State, have caused a corresponding 
rise to the westward ? 
The valleys of Western New- York, so far as examined, ah aid in 
proving the foregoing statements ; and if we can find that those Avhich 
are excavated deepest have been the largest water courses, we have 
another fact in proof of our position. The discharge by way of Cay- 
uga lake to the Susquehannah, continued till the inland sea was reduced 
below the level of 980 feet. Seneca lake and the valle}^ south, conti- 
* The shores of the lake generally present, as the lowest stratum, a blue or variega- 
ted marly clay, surmounted by a few feet of Avhite or yellowish clay, and above this, 
sand. Sometimes gravel is deposited in what appear to have been excavations in this 
day. 
