438 
[Assembly 
Angelica, or the one in which the river now flows from its source to 
Portage. At the south hne of the State, this valley is probably not less 
than 1,600 feet above the ocean. When the waters were at this eleva- 
tion, the margins of the ancient sea could scarcely have been defined, 
for having so many outlets, it would remain at no settled elevation for 
any considerable period. 
The subsequent condition of this valley has been one of great inte- 
rest. After the waters had ceased flowing in so many directions, and 
the inland sea was reduced to its first stationary point, that portion 
south of Portage, was left as a lake of the same dimensions as the val- 
ley at the present time, with all the small streams and the sources of 
the Genesee flowing into it. This lake discharged its waters by a 
gradual descent into the inland sea, which at that period was little be- 
low it. At subsequent periods the inland sea was so far reduced, that 
the lower valley» or that between Rochester and Dansville, was left a 
shallow lake, having its outlet by way of the Irondequoit, and more re- 
cently, by way of Rochester. During these periods, the streams flow- 
ing into the valley, at, and about Dansville, brought down loose mate- 
rials which were deposited over the bottom of the lake, the finer mate- 
rials being carried forward suspended in water. This was also the 
condition of the discharge from the upper lake, by way of Portage ; 
pebbles, sand and mud were brought down, the coarse materials being 
deposited first, while the finer were carried forward and deposited in 
more quiet water. 
An examination of the Genesee flats furnishes sufiicient proof of this 
theory. For many feet in depth the deposit consists of fine sand and 
clay, intimately mixed, the same materials which are now being depo- 
sited in every lake by its tributaries. The evidence does not rest here, 
for if we examine this deposit, we find lines of stratification or deposi- 
tion, the direction sloping from south to north, and the very same which 
we should expect, if the materials composing it were pushed gradually 
forward over the bottom. The first deposit would be made at the em- 
bouchure, and would consist of a mass sloping ofl" towards the centre 
of the lake ; the next would follow this, a second and third deposit in 
the same way, would continue the slope towards the north. As we 
advance towards what we suppose to have been the inlets of this lake, 
we find the materials of such character, that they could not have been 
brought down by any except a powerful current. 
