186 On the Silurian System of the Lake Superior Region. 
the first eight miles after leaving the lake, we meet with the high- 
est beds of limestone in the series which occur on this river. Al- 
though its descent is rapid, yet it is unequal in its rate, and these 
inequalities appear to be due to undulations in the strata, which 
can be detected at several points. For the most part, the stream 
is very shallow, and its bed rocky.* 
Along the whole exteut of this exposure of the rocks, whether 
examined continuously, or at intervals, there is no difficulty in 
identifying different portions with their New York equivalents. 
When taken as a whole, and all of the beds examined in connec- 
tion, the principal subdivisions, such as the Chazy, Birds-eye, and 
Trenton limestones, are readily identified, not only by their litho- 
logical characters, but by their organic remains. Even in the 
arenaceous layers, which form some twenty feet of the whole 
thickness, we not only detect numerous species of fossils peculiar 
to the Trenton limestone, but many peculiarities of bedding, and 
other characteristics, which, though not easily described, are 
readily understood and comprehended by the geologist. 
t is deemed unnecessary to give farther details of the variable 
features of these limestones along the Escanaba river; in all the 
localities examined, they offer little of economical value, aside : 
from their application to building purposes. ' 
At the mouth of Rapid river and along its borders, and also at 
the mouth of the White-fish and the head of Little Bay des No- 
quets, the ‘Trenton limestone is exposed, exhibiting the same . 
lithological characters, as at the upper dam on the Escanaba. — 
arther explorations made by Mr. Whitney, along the White 
fish river, in crossing from Little Bay des Noquets:to Lake Supe 
rior, proved the occurrence of the Trenton group, for the distance 
of fifteen miles, or moré, from the head of the bay. The spec 
mens procured are filled with fossils, principally Leptena sericea, 
and occasionally with ZL. alternata and Orthis testudinart@, 
while, in lithological characters, they agree with those observe 
on the Escanaba and Manistee. The country along the White 
fish river is low, rising little above the river margin; consequent 
ly, there are no cliffs, or escarpments, where the strata are e* 
posed to any extent, and specimens can be procured only at the 
water’s edge. This river then, like the Manistee, affords ev! 
dence of the existence of certain groups, but does not admit © 
continuous observation as to their succession, thickness, and im- 
portance. 
* The name Escanaba signifies Smooth Rock, given for the reason that the stream 
often flows for considerable distances, over the smooth surfaces of the slightly 1 
clined rocks. The inequalities caused by the offset of particular beds, give TIs€ 
numerous rapids, and render the navigation so difficult that even a small eel 
a ag: the when the water is low, except by using setting” 
poles armed with steel points. 
