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 

 eould never be drained in this way, though a lake 

 situated above tide-water might. Neither was it a 

 salt-water lake above tide-watermark ; 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, 



