Remarks on the Geology of Western New York. 245 
has been considered peculiarly characteristic of transition rocks, also 
occurs in the superincumbent shale. It has been found at the mouth 
of Eighteen Mile Creek, on the shore of Lake Erie. Specimens 
may also beseen at Mr. Barnett’s museum at the Falls, found in that 
vicinity. In speaking of the trilobite family, Dr. Thompson, in his 
recent work on Mineralogy and Geology, says that “no traces of 
them have been discovered in the lias, nor new red sandstone, nor 
even in the coal beds.” 
With the cornitiferous strata above described, terminates what I 
believe to be the upper transition limestone. The superincumbent 
strata present a mixed character. The fossils are mostly the same 
as those already mentioned ; showing that the same animals contin- 
ued to inhabit the same seas; while on the other hand, the thin 
beds, or rather insulated patches of bituminous coal, mostly, I should 
think, the product of single plants, begin to make their appearance ; 
showing likewise, that some portion of the earth’s surface near by, 
had emerged from the waters, and was in a fit condition to support 
the. growth of vegetables. I have not even here met with the im- 
pression of leaves, &c. but farther research may yet bring them to 
light. - 
The lower portion of these strata, where seems to commence the 
change from the transition to the coal formation, are mostly com- 
posed of soft shale or slate, sometimes bituminous, and containing 
large quantities of iron pyrites. This shale alternates with strata of 
impure limestone from one inch to one foot in thickness, which also 
contain iron pyrites disseminated and forming a thick coating on their 
under surface. The lower portion of thisshale contains more or 
less carbonate of lime, varying from the least perceptible quantity 
to one half or more of its weight; constituting a marl of great value 
for agricultural purposes. It is principally in this marly state that 
the fossil shells occur. Many of the bivalves are exceedingly per- 
fect, retaining all the delicate markings on their exterior surface; 
while others are twisted and contorted in a singular manner. Oth- 
ers again are in a collapsed state, one valve having been crushed 
in, as if done by great pressure. Beds of this marl have been 
opened in Geneseo ail South Avon, where it was mistaken for gyp- 
sum, and used as such in the vicinity ; and it would seem, from the 
results, with equal advantage to the agriculturalist. One specimen 
from South Avon yielded thirty six, and another sixty per cent. of 
“carbonate of lime. In neither could I detect any a 
