296 
GEOLOGY OF THE FIRST DISTRICT. 
eddies on a large scale, and eventually sinks ; we can scarcely be surprised at the vast accu¬ 
mulations of ancient vegetation over certain areas, where, from evidences that can be adduced, 
similar eddies must at that epoch have been formed, and similar effects have been produced. 
This mode of explaining the origin of the coal formation in North America, will easily ac¬ 
count for the tropical vegetation found even in the frigid zone ; as one part of the equatorial 
current must have passed to the Polar sea between the Rocky mountains and Lake Superior, 
and may be expected to have floated the vegetation of the tropics. 
I would not urge this matter, however, to the extent of contending that the climate has not 
greatly altered since the carboniferous epoch; for we have numerous evidences on that point, 
that may be considered as conclusive, 
1. Mr. Lyell has satisfactorily shown that a different distribution of land and water, even 
without varying the absolute quantity, would materially influence the climates of the earth. 
2. We have indubitable evidence that most of North America and Europe have emerged 
from the bed of the ocean since the carboniferous epoch. 
3. Fossil plants, animals, testacea, zoophytes, etc., all indicate that they belonged to a 
warmer climate than the present; and those organic bodies to which reference is now made, 
lived and died where they are now found ; and they are diffused over vast extents where 
the climates are now extremely varied, and are not all probably due to the genial influences 
of the warm equatorial current. 
4. There are no known evidences of ice on the earth’s surface until after the epoch of the 
carboniferous strata, and none with certainty ascertained until about the period of the drift 
deposits.* 
The effects of large tracts of land emerging from the waters of the ocean in the temperate 
and frigid zones, such as we know have emerged since the carboniferous epoch, and even 
without the disappearance of any between the tropics beneath the ocean level, might be ex¬ 
pected to be as great in changing the climates of the different regions of the earth as the 
changes we perceive, and independent of the secular refrigeration of the globe. 
The plants of the carboniferous epoch are said by botanists to be vascular cryptogamic 
plants of tropical characters, and to indicate an insular, rather than a continental flora. Those 
of the more recent formations in the upper secondary and tertiary are dicotyledonous. The 
changes have been successive. 
The coal formations of the United States, between the Blue ridge and Rocky mountains, 
have been already slightly alluded to on pages 2 and 3 of this volume. One of these, which 
we may be permitted to call the Ohio coal formation, as it nearly all lies within the basin 
drained by the Ohio, has its northeastern extremity near the Delaware river, in New-York, 
* Dr. Joseph Barratt, of Middletown (Conn.), an ardent naturalist, and favorably known as a botanist, showed me examples 
of what he considered to be the effect of the congelation of water in the red sandstone near Middletown, in 1837. The exam¬ 
ples he shewed me bore some resemblance to the long shoots of crystals often seen on frozen mud; but they were not so striking 
as to force conviction on my mind. Dr. B. is, I believe, the first observer of such facts. I hope he and others will investigate 
the subject farther, and ascertain if these and similar appearances are due to frost. 
