434 [Assembly 
regard to the St. Lawrence, we have some mformation of the evidence 
that this river formerly flowed out at a much greater elevation, and that 
it has excavated for itself a channel in the rocky strata towards its 
mouth. We have also more conclusive evidence of this fact, in 
the course of the Susquehannah, and also in the channel of the Mo- 
hawk, excavated through the primitive barrier at Little-Falls. The 
Hudson has at one time found a barrier in the Highlands, which has 
been removed by the combined agency of its own waters and those of 
the St. Lawrence,* or indeed of a much larger amount of water than 
now flows in both these rivers. 
Thus far we have no data to guide us regarding the barrier across 
the Mississippi, or precisely at what point it existed. It appears, how- 
ever, to have been one of the last formed outlets to the inland sea. 
In the western part of the State of New- York, many of the valleys 
may have been deepened or partially formed by the passage of the wa- 
ters of this sea to the great outlet south, (the Susquehannah.) The 
lowest elevation between the valley of Cayuga lake, and the Susque- 
hannah at Owego, is 981 feet. This corresponds nearly with the base 
of the highest margin of this sea, which Mr. Roy has observed in Cana- 
da, (viz : 996 feet,) at which point he observes, the inland sea must 
have remained stationary for a long period. The elevation of the val- 
ley between Seneca lake and the Chemung river, is 890 feet. Mr. Roy 
recognizes in Canada, a well defined margin at 914 feet. It therefore 
follows, that a discharge of twenty four feet in depth, took place through 
this valley at that period ; and we have evident marks, in the character 
of the valley and the transported materials, that a violent current has 
passed through it. At this period, we know that the discharge by way 
of Owego to the Susquehannah had ceased. The valley from Seneca 
lake to the Chemung river, must have been the principal, or almost 
* It may be objected to this view of the subject, that the barrier across the Hudson 
at the Highlands, could never have been 1,000 feet above tide water. This may al- 
ways have been the elevation of these hills, and the Hudson, in that case, formed one 
of the earliest outlets of this sea. There may have been, also, some change in the 
level of the land since that time, for we know that the tertiary of Lake Cham- 
plain is deposited upon rocks which are scratched and worn by the current formerly 
flowing in this valley, and which came by the way of the St. Lawrence. Since that 
time, this basin has been submerged beneath the ocean, the tertiary fossils have lived, 
died and been covered with clay, sand, &c. and the whole raised to its present eleva- 
tion ; whether it be the same, or higher or lower than it was before the submergence 
we cannot at present determine, 
