VALLEYS. 
13 
pally from the northern highlands of New-York. It is this great extent of drainage from an 
elevated ’wooded region which gives such a constant and regular supply of water, and it is 
this which ensures its continuance. If, however, we look forward to a time when a large pro¬ 
portion of this wilderness shall be under tillage, there is some probability that quite a different 
state of things may exist in this respect, especially as it regards the Hudson. This river rises 
wholly under the shadow of forests, wild and uncultivated. If now those forests were to be 
replaced by pastures or open fields of any description, the quantity of rain which now falls 
would be materially diminished, especially during midsummer; or if it should not be dimi¬ 
nished, the evaporation from the surface would be greatly increased, so that the result would 
remain the same under either condition. Less will flow in the natural channels, and the supply 
for navigation may be so far diminished as to prevent, or if not prevent, greatly impede the 
navigation, and interfere with its employment for moving machinery, or the various purposes 
to which water is applied. 
The most important valley of the Second Geological District is the Champlain; but only 
a small proportion of this belongs strictly to New-York ; still I have considered it as neces¬ 
sary to investigate its physical as well as its geological relations as a whole. The length of 
this valley is one hundred and eighty miles, if it is to be considered as extending to St. John’s ; 
but it appears to open into the valley or basin of the St. Lawrence twenty miles to the south. 
The greatest depression of this valley is between Westport, Burlington and Port Kent. By 
sounding close to the edge of the perpendicular rocks about four miles north of Westport, I 
found the depth to exceed three hundred feet. By soundings at other places in this part of 
the lake, its depth has been found to be six hundred feet; it extends therefore five hundred 
feet at least below the level of the ocean. Situated as the lake is, entirely upon the western 
side of the valley, its bed must be regarded as a deep chasm principally in the primary rocks ; 
for from the lake shore upon this side the slope is abrupt along the whole portion where the 
several mountain ranges reach it, or excepting those portions of it which are bordered by the 
minor valleys. The character of the slope upon the east side is quite different from the west; 
that is, it is longer and much more gradual in its descent; it comprehends most of the valley. 
In a direct line, or a line perpendicular to the course of the lake and the Green Mountain 
range, it cannot exceed twenty-five miles, and probably the average width of this valley is 
about twenty miles. At many places the lake is bordered by steep banks composed of clay 
and sand, the greatest height of which is about one hundred feet. It is not my purpose, in 
this place, to consider the nature of this formation or its age, but it is proper to remark that 
it is marine, as at many points it furnishes an abundance of fossils belonging to those species 
which are now inhabitants of the sea on the Atlantic coast; those too which belong to the 
same latitudes. Thus, I have found the Mya arenaria, Mya truncata, Natica clausa, Trito- 
nium anglicum, Tritonium fornicatum, Scalaria groenlandica, Saxicava rugosa, Tellina grcen- 
landica, Balanus miser, Pecten islandicus, Terebratula psittacea, Modiola -, and several 
other shells, amounting in all to about twenty species ; all of which, as has been remarked, 
belong to the present Atlantic shore. We may therefore consider the sediment of this valley 
