HAMILTON GROUP. 
195 
mixed with foreign materials. The soil varies, however, from a stiff clay to sandy or gravelly; 
and sometimes these divisions are arranged over considerable areas, apparently without refe¬ 
rence to the rocks beneath. 
As an example, we find, in passing over this group from Seneca lake westward, that there 
are alternations of sandy, gravelly and clayey soils, as far as the valley of Flint creek ; passing 
this, the soil is for the most part sandy and gravelly, passing into a gravelly clay, till we reach 
the summit between Flint creek and Canandaigua lake ; and descending from this point to the 
outlet of the lake, the soil is almost wholly clay. Again, on the west of this lake the soil is 
clay or clayey gravel, till we arrive in Bloomfield, where it varies from a light sandy loam to 
gravel and gravelly loam, with but little clay except in the low grounds. 
Farther west, and particularly in the valleys, the soil is more clayey where this group 
extends. Approaching Lake Erie, the northern drift has accumulated above these rocks, and 
the soil presents a gravelly and loamy character, with occasional tracts of clay in low grounds, 
or in places where the rock approaches the surface. Along the shore of Lake Erie, where 
this group extends, there being no considerable proportion of drift, the soil is extremely clayey, 
as any one may recollect who has travelled the road southwest from Buffalo in the wet season. 
Whatever kind of soil prevails, however, it is always highly calcareous, and over the whole 
extent of the group is of unequalled fertility. A large proportion of the famous “ Genesee 
country*’ lies upon this group, and the fertility of this soil is well known. The materials de¬ 
rived from the destruction of the rocks of this group are largely intermingled with the soils to 
the south of their southern boundary, and contribute largely to the fertility of the slopes under¬ 
laid by rocks of the Portage group, and the broad valleys which extend southward nearly to 
the Pennsylvania line. 
Organic Remains of the Hamilton Group. 
The contrast in the prevailing fossils of this group with those of the last is as great as in 
the lithological products of the two formations. We sometimes indeed meet with a species 
which occurs in the limestone below, but except in a few instances these recognitions are rare. 
Some of the more abundant corals are identical, but the great number of new forms renders 
them of less importance, and in all instances they are too few in number to produce any doubt 
or difficulty in identification of strata. 
Shells both of the Brachiopoda and Dimyaira have immensely increased, and in many single 
localities from twenty to fifty species of fossils may be obtained. The great abundance and 
perfection of these fossils offer strong inducements for the study of this branch, and perhaps 
no other department of Natural History, except Botany, will yield so rich a harvest from 
limited areas as Palaeontology. If their occurrence in the lower rocks, as represented in this 
volume, is interesting, their great number and exquisite perfection in the Hamilton group will 
certainly delight the mind of every lover of Nature. Here it seems, that instead of extract¬ 
ing them from the solid rock, we are culling them from the dried ocean mud, which a late 
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