of the Older Formations of the United pt 17 
the caleareous or chemical deposits i increase in A same di- 
rection. * 
The origin, therefore, of the deposits of sand and mud has 
been at the east, while circumstances more favorable to the 
production of corals and the formation -of calcareous matter, 
have existed at the west. 
i We also find that dependent upon, or neni with these 
operating influences, have been the character, degree of devel- 
opment, and number of organic forms which inhabited the 
. ocean. We find that all those. forms which flourished most 
. Upon, or were dependent upon, a calcareous bottom, increase 
ina wonderful degree toward the west, while those affecting 
sandy or muddy bottoms, are more abundant at the east, be- 
i coming nearly or entirely lost at the west. The aer cu 
stages are marked by admixtures of the two kinds of forms, and 
"d — abundance of forms which flourish in calcareous 
The speculations in regard to the conditions of this ancient 
. ocean during these periods, Id occupy too much time at 
. Present, and we can only hastily glance at some conclusions. 
Si okts evident, from the fact that these calcareous deposits are 
.. often succeeded by immense mechanical depositions i in the form 
_ of mud and sand, that the condition of the ocean bed changed 
u intervals. The growth of corals would only take place at 
. €ertain depths, and below this they would all perish. Now it 
. Would seem that the bed of the ocean was subject to oscillations, 
i by Which in one place, covered with corals and calcareous mat- 
fer, itsank down and allowed an immense deposition of sand and. 
mud to accumulate ; and again, this deposit ceasing, the bed 
pt of the Ocean gradually returned to the condition in which it 
` again Supported a growth of corals a. ad -their accompanying or- 
. ganic forms. ‘The thinning out therefore of a calcareous de- : 
cmd. pe a condition of the ocean unfit for supporting 
: : which were the principal agents in giving origin 
| those immense calcareous deposits of our country. Such 
? may infer was its ec much of the eastern por- 
VOL. y. — enh ex Q 
