some 
- 
a) 
re nameless, until, some countless ages afterwards, President 
Hitchcock tracked them out, found evidence that they were no 
unworthy representatives of the feathered tribe, and gave them 
and their reptile associates befitting appellations. 
uch vast regions of eruptions could not have been without 
effusions of hot water and steam, and copious hot springs. An 
may not these heated waters and vapors, rising through the 
crystalline rocks below, have brought up the copper ores, that 
are now distributed, in some places, through the sandstone? 
The same cause, too, may have given the prevalent red color to 
the rock, and produced changes in the adjoining granite. 
er the era of these rocks, there is no other American rec- 
ord during the European Jurassic Period. 
_ In the next or Cretaceous Period, the seas once more abound 
in animal life. The position of the cretaceous beds around the 
Atlantic border shows that the continent then stood above the 
valley, which, from the Silurian, had generally been the region 
occupied to a 
poly new Fauna, excepting, ee to Professor Tuomey, 
doubt, The continent was now more elevated than in the pre- 
drawn from the region of Iowa and Wisconsin, so as not to 
teach beyond the limits of Tennessee.t 
. * Mr. J. Deane of Greenfield was also an early explorer of these tracks, and 
1s now engaged in publishing on the subject, illustrating his memoir with plates of 
great beauty and perfection. 
, t The recent investigations of F. B. Meek and Dr. J. V. Hayden, have shown (Proc. 
Acad. Nat. Sci. Phi a em 111, 1856,) that while there is much 
ib the Nebraska region d there is also it the head waters of the 
: uri some marine t ry. region investi between the 46th and 
1 parallels of North latitude and the 100th and 108th degrees of longitude : but 
it is not ascertained whether the body of salt water thus ir ted an 
ted area, or an arm fr e Me e shells, (species of Ostrea, Corbula, 
' and Cerithion) do not satisfactorily fix the age of the tertiary, but iy nia 
authors say, that it may be the older Eocene, They occur in the same 
