ROCK FORMATIONS OF THE WESTERN STATES. 
515 
the nature of sedimentary deposits, it can be only the finer parts that ever reach to great dis¬ 
tances from their origin ; and, reasoning thus, the fauna of the deep and distant parts of the 
ocean, if any exist, would be uniform, not being liable to destruction or change of condition 
from the rapid invasion of variable deposits like those near the shore. The deposition of a 
coarse sandstone or conglomerate succeeding to a shaly mass, would in all probability destroy 
the greater number of living forms as far as it extended. But at the same time, the finer 
materials produced by the same cause, would extend far beyond the limits of the coarser ; and 
thus approximating, in some degree, to the lower mass, the fossils might be continued long 
after they were destroyed at another point. 
One of the most interesting changes in the products on going westward, is the great increase 
of carbonate of lime, and the diminution of shaly and sandy matter, indicating a deeper ocean 
or greater distance from land. The source of the calcareous deposits is thus shown to have 
been in that direction, or in the southwest; while the sands and clays had their origin in the 
east, southeast and northeast, producing, during long intervals, a turbid condition in the waters 
of these parts, unfavorable to the production of calcareous matter, and the formation of chemi¬ 
cal deposits. In New-York we are evidently upon the margin of this primeval ocean, as indi¬ 
cated in the character of the deposits as well as organic remains ; the southwest unfolds to us 
a portion of greater depth and more quiet condition. 
