ORISKANY SANDSTONE. 
169 
and the singular association of fossils which are found in it. Sometimes, though it is but 
a thin mass, not exceeding a foot in thickness, it is composed almost wholly of organic 
bodies, being so crowded together that they appear a mass of shells. In addition to the 
number of the fossils, it is highly interesting to observe the sudden transition of genera 
and species that occurs in passing from the Delthyris and Encrinal limestones to the 
Oriskany. Almost every species in the two former rocks seems to have perished about 
the time the latter was in the process of deposition. To learn at this late day the cause of 
this sudden extinction of life in so many animals, is certainly no easy matter. 
The Oriskany sandstone, being a clean sandy deposit, does not seem a sufficient cause 
in itself for occasioning such a loss of life among the tenants of the deep ; though there is 
no doubt of the position that the mollusca have their favorite habitations, a choice in the 
materials in which they bury themselves, and in which they may seek their food. Still 
one would hardly suppose that simple sand would prove so injurious to life, as to destroy 
entire races. Hence it is more natural to suppose that some change preceded the deposi¬ 
tion of the rock, to which must be attributed the catastrophe under consideration. This 
change may have consisted simply in the elevation of the bottom of the sea, while the 
preceding deposits were accumulating. This seems to be a rational hypothesis, inasmuch 
as there is a change in the kind of materials which compose the sandstone. Previous to 
this rock, there were calcareous deposits, mixed with sandy argillaceous ones ; afterwards 
there were siliceous deposits, which must have come from another direction. The reader 
of course will understand, that all the rocks which we have had under consideration in this 
chapter, are formed of sediments abraded from preexisting rocks, brought from a distance 
by rivers, to the oceans or seas which existed at this era. Again, the beings belonging 
to the era of the sandstone were not only suddenly ushered into life, but they were as 
suddenly put out of life, or, in other words, were destroyed as suddenly and as uncere¬ 
moniously as their predecessors, and after an extremely brief period of existence. 
Characters of the Oriskany sandstone. It is composed in the main of coarsish angular 
sand : in this respect, it is unlike many of the sandstones in the New-York system. The 
sand is usually gray or yellowish, but sometimes white. Pebbles or rounded stones are 
not common, if they ever exist in it: it is, at any rate, far from being a conglomerate. 
Although the sand seems to be held together without cement, yet the presence of lime is 
indicated by effervescence in a very large proportion of the rock, even in that portion which 
to the eye appears altogether sandy. 
Localities where this rock is developed. Near the village of Leeds in Greene county, this 
rock is crushed in, and concealed or greatly obscured by contortions which it has suffered 
along with its associates (See PI. XX. sec. 5). But the Helderberg range is the region 
where this rock, for a thin one, is quite conspicuous, namely, on the road to New-Scotland, 
near Mr. Clark’s ; in Knox, on the road to Schoharie ; at Schoharie, on both sides of 
the valley, but more particularly on the western terrace, and also at Cherryvalley; at 
Auburn, and four miles west of Auburn, on the road to Cayuga bridge. It forms an 
[Agricultural Report.] 22 
