= 
Notes on American Geology. eae 
One remarkable fact is, that the same day, and about the same 
time in the day, two other similar whirlwinds were experienced, 
which moved in nearly parallel lines, one passing through War- 
wick, Massachusetts, and the other about the same distance to 
the northeast. 'They were both less violent; but one of them 
at least, the one through Warwick, did considerable damage. 
The — of the other I never had. 
Art. IV.—Notes on American Greology ; by T. A. Conran. 
Observations on characteristic Fossils, and upon a fall g, Tem- 
perature in different geological epochs. 
Ir has sometimes been objected, that the value of organic re- _ 
mains, as a basis on which to build the superstructure of geologi- 
cal science, is lessened by the fact that certain species range 
throughout different formations; but these are far from being so 
numerous as is sehatrully: suigkscuod. An instance never occurs in 
this country, where the species of one formation are continued 
into an upper one in such numbers as to cause the least perplex- 
ity or dispute regarding its. geological age. - All the various eras 
are admirably recorded, each by its peculiar group of animal or 
vegetable remains ; and to him who has carefully studied them, 
they are quite as intelligible as if the hand of nature had arranged 
them in a cabinet for his use. The few species of a lower, dis- 
covered among those of an upper group, are not always to be re- 
garded as contemporary with the latter, as some of them are clearly 
accidental. Every sedimentary stratum must have been derived 
from a rock previously formed, and of the first sedimentary — 
originating in the destruction of primary masses, we, of course, 
‘take it for granted that such forms of animal and vegetable life 
originated in the ocean in which those sedimentary | strata were 
deposited. But when these, disintegrated in their turn, have 
been, at a more recent period, swept by currents into other seas, 
we may expect to find occasionally, some few of the species 
which originally existed, carried with the debris, and thus min- 
gled with a group very different from that with which they origi- 
nated. It is true, that in the present state of our knowledge of 
