268 
TERTIARY FORMATION, 
The tertiary also forms a deposite in the coun- 
ties bordering both sides of the Hudson, from its 
source to the Bay of New- York, furnishing inex- 
haustible beds of clay for the making of bricks and 
pottery. This section of country is universally be- 
lieved by the inhabitants to have once formed the 
bed of the ocean, and the late Dr. Mitchill and 
others have supposed that it was drained by the 
bursting of the Hudson through the Highlands at 
Newburgh. But it is very evident that this region 
was covered by salt water, and an arm of the sea 
could never be drained in this way, though a lake 
situated above tide-water might. Neither was it a 
salt-water lake above tide-water mark ; for the sum- 
mit line of the Champlain Canal is only 147 feet, 
and the tertiary extends 200 feet above the lake, 
and the present level of the lake being only 93 feet 
above tide- water. As the tertiary marks the limits 
of the ancient water, it is evident that, rising 200 
feet above the lake, it must have communicated 
with the sea by the St. Lawrence Channel on the 
north and the Hudson on the south, thus convert- 
ing it into an arm of the sea.* The only rational 
way to account for the draining of this extensive 
tract, as well as many other similar ones in our 
country, is to suppose the land to have been for- 
merly elevated by some force beneath. Such ele- 
vations will also account for the numerous floods 
which have at different times swept over the sur- 
face of the earth ; and it is by no means improbable 
that " Noah's flood" was caused by the upheaving 
of some extensive mountain range, for we are told 
that " the fountains of the great deep were broken 
up.", 
The tertiary strata of the United States are now 
ascertained to belong to all the four periods into 
which Mr. Lyell has divided this formation, viz., 
* E. Emmons. 
