Review of the New York Geological Reports. 167 
state are found amongst the rocks of this group. The highest 
perpendicular fall of water in the state is produced by the rocks 
of this group, and in none others do we meet with more grand 
and striking scenery. ‘The pedestrian often finds his course im- 
peded by a gorge several hundred feet in depth; and in the 
very bottom of this, and scarcely perceptible, is the winding 
stream, the only representative of the once powerful torrent that 
has excavated the deep channel. Farther on, above or below, he 
may see the little stream dashing over a precipice, and almost dis- 
appearing in spray before it reaches the bottom; here, however, 
it gathers itself in a deep pool from which it flows on quietly as 
before, or gurgling and dashing through the fragments of the 
fallen cliffs, it finds its way into the gently sloping valley of the 
softer shales.’’ . 
The soils overlying the formations up to and as far south as 
the Tully limestone, are highly calcareous ; that derived from the 
higher rocks, south of that geological zone of the state of New 
York, is deficient in calcareous matter, as might be anticipated 
from the absence of limestone beds. It is, therefore, not, on the 
whole, so fine a wheat growing country as the lower ground fur- 
ther north. However, where the lower argillaceous beds of the 
Portage group crop out, on the northern slopes of the group, it is 
stiff and clayey land and nearly as good for wheat as can 
found. But as in ascending it becomes more and more siliceous, 
and the included gravel less rounded by attrition, the wheat 
crops are less abundant and more uncertain. These soils are 
better adapted for pasturage, and make good stock farms. 
_ “ Almost every ravine and stream,” says Hall, “ upon the eleva- 
tion which rises to the south from the Hamilton group, exposes 
the rocks of the Portage group in greater or less perfection.” 
The thickness of the various members of this group, taken to- 
gether, is estimated at 1000 feet. 
great variety of concretionary forms occur throughout the 
mass. In the black shales they are mostly spherical ; in the green 
or greenish-black they are very flat or lenticular; the latter being 
crystalline and more argillaceous than the former. Their 
regularity and the imitative forms which they occasionally as- 
sume are truly astonishing ; it is not surprising that the uninitiated 
Should often mistake them for petrified tortoises and turtles. On 
the nesee river and Lake Erie a peculiar structure is observable, 
according to Hall, on the outer surface of some of these concre- 
Hons, denominated “cone in cone ;’ a similar structure is observ- 
able in wedge formed layers in the same formation at the above- 
mentioned localities, From the remarks of this author respect- 
ig this appearance in layers of the Portage group, we infer 
that he supposes it due merely to the powers of segregation. 
This may be so, but we have been struck with the analogy which 
