CHEMUNG GROUP. 
2C1 
larly of the larger and deeper ones, consists of a large admixture of northern materials, among 
which maybe recognized the pebbles of the different limestones and of the Medina sandstone. 
Sometimes pebbles of the harder strata of the Hudson-river group occur with these, and it is 
probable also that some of the limestone pebbles may be of the lower limestones north of Lake 
Ontario and of the Mohawk valley, although they are not distinguishable by their fossils, being 
usually worn very small. 
These circumstances often cause a contrast in the productions of the neighborhood; the 
valleys, from the calcareous nature of the soil, being good wheat lands, while that of the hills 
beyond the influence of northern drift is unfit for growing wheat after the first few years from 
its clearing, unless properly manured. This soil, from its compact nature, is better adapted 
to grazing than to grain-growing, and this adaptation is beginning to be well understood. 
Organic Remains of the Chemung Group. 
The rocks of this group abound in fossils, presenting a great variety of forms of the same 
genera. In the Fourth District, few forms known in the Hamilton group extend into the 
Chemung. Species of the Brachiopoda are almost equally numerous with the Hamilton 
group, while Aviculas are much more abundant both in species and individuals. The species 
and individuals of Nucula and Cypricardia, and some others, are about equally numerous in 
both groups. Trilobites are rare, and there are but few species of coralline fossils. 
The fossils are often very unequally distributed through the strata ; localities being found 
where few or almost no fossils can be obtained, and again the strata are completely charged 
with them. Different localities also often present a great abundance of certain forms which 
are rare in others. 
The green sandy shales of Rockville and Phillipsburgh contain a great abundance of fossils, 
mostly of Avicula, Lima, Cypricardia and Inoceramus, while Delthyris and Atrypa are 
much less common. Again, the dark sandstones and sandy shales of Painted-post, Jasper, 
Troupsburgh and Dexterville, contain myriads of the little Orthis unguiculus , and large num¬ 
bers of Delthyris, Atrypa, and more rarely Avicula. At Chemung narrows, several species 
of Avicula, with large numbers of Atrypa and Strophomena, are found, with very few of the 
fossils of the localities before noticed. Scarcely a locality abounding in fossils can be exa¬ 
mined, but some new form will be discovered. In this respect this group offers a contrast 
with the Hamilton, which, where well developed, will yield nearly all the known fossils in a 
single line of section. This remark applies to the Fourth District, though changes are mani¬ 
fested farther east. 
In the following woodcuts, the fossils are grouped principally according to the generic re¬ 
lations, and they embrace the greater number of forms which have been seen in the district. 4 
* A large number of these will not appear in this place, but may be found in the forthcoming volume on the Paleontology 
of the State. 
