ONONDAGA LIMESTONE. 
155 
The best locality for examination of this rock is on the farm of Mr. Youngs, in the town 
of Amherst, a mile west of Williamsville. At this place the rock is well exposed in all its 
varieties. Being a point from which large quantities of lime are taken to supply the city of 
Buffalo, the rock has been quarried at several places, much increasing the facilities for ob¬ 
servation. The grey crinoidal mass is much better developed here than I have elsewhere 
seen it, the masses of coral are larger and more numerous, and finer specimens can be ob¬ 
tained. On the brow of the hill it is succeeded by the next rock, which however appears to 
contain little hornstone. 
From the point just noticed, the rock diminishes westward, and at Black-Rock there is but 
a thin stratum marking its place. At the same time the chert or hornstone of the next rock 
increases, and Cyathophylli and a few masses of Favosite have been found in the strata com¬ 
posed in a great measure of this material. 
From the facts mentioned, the inquiry naturally suggests itself, as to the conditions under 
which this rock was deposited. It has already been seen that at some points it attains consi¬ 
derable thickness, very remarkable for the abundance of its fossil contents, as well as the 
character of the rock, while at others it forms a thin stratum scarcely distinguishable except 
by its position. The materials of the formation therefore have either been very unequally 
distributed over the bed of the ocean, lodging in depressions of the previous surface, or these 
greater developments are only local, the materials being derived from the growth of coral and 
other organisms in or near the situation they now occupy. Although the former cause may 
have operated to some degree in many localities, it will not account for the phenomena wit¬ 
nessed in all. The thin strata forming connecting links between the points of greater develop¬ 
ment are probably the finer portions of the thick strata which were transported by the water 
and spread over the bottom, where few or no organic forms existed. In this respect, these 
thick portions resemble a line of detached coral reefs, which we may fancy to have skirted the 
margin of this ancient ocean, and like many modern ones they may have flourished for a long 
period entirely disconnected, and with a deeper ocean between them. That these deposits 
are local, or have for the most part been produced in their present situation, seems proven 
from the abundance of coralline forms, many of which retain the position in which they ori¬ 
ginally grew. Some of the masses of Favosite are several feet in extent, and from one mass 
several wagon loads were taken on the supposition that it was gypsum. It is plain that such 
as these could never have been transported far, even if they have been moved at all. It is 
true that many of the smaller ones are broken up, and others are found turned upon one side, 
or completely reversed, showing the action of waves. The Crinoidea which appear to have 
formed a large share of the deposit, are broken up and their remains scattered, though columns 
of a foot or more in length sometimes occur. The Cyathophylli are generally thrown down, 
though they are usually perfect. 
From the fragile nature of the Crinoidea, any force sufficient to overturn the broad-based 
Favosites and other similar corals would destroy these, and scatter their fragments over the 
bottom, filling up the spaces between the other corals. Many other small or fragile corals, 
20 * 
