76 Geology of America. 
from Massachusetts to Florida. Thus an identity, or at least 
a close correspondence (for we must speak cautiously till the 
fossils are carefully compared) has been found to exist not 
only in the oldest but the newest formations, over a space ex- 
tending from Austria to New Orleans. The Tertiary rocks 
are believed to have been originally formed in detached basins; 
and never to have been continuous, and their recurrence in 
distant parts of the globe was therefore less certain than in 
the case of the primary and secondary rocks. 
Grooved and polished rocks—Diluvium—Boulders.—The 
phenomena of polished, scratched, and grooved rocks, are more 
common, Dr Hitcheok thinks, in the United States than in 
Europe. If the formations of New England were denuded, 
“one-third of the surfaces,” he believes, “ would be found 
smoothed and furrowed.” The diluvium or drift is also simi- 
lar to some extent, in composition and appearance, to that of 
Britain. The lowest portion is of sand, clay, gravel, and 
boulders, seldom stratified ; next are horizontal layers of fine 
blue clay ; above this is a bed of sand; and scattered over the 
whole surface are insulated blocks, sometimes rounded, and 
sometimes angular. The chief difference between these de- 
posits and ours, is in the second, corresponding to our upper 
diluvial clay, which we have never seen stratified in this coun- 
try. The diluvium forms conical and oblong tumuli, and tor- 
tuous ridges ; features common to it here. 
The striz and grooves on the rocks generally point south- 
easterly, and this has been found to hold true, with small 
local exceptions, over a breadth of 2000 miles (meaning, we 
presume, the region from Florida to Canada) ; 2. They appear 
on mountains to the height of 3000 feet, but not on those ex-’ 
ceeding 4000; 3. They are feebler and fainter in the south of. 
the United States than the north; 4. In New England erratic 
blocks have been traced to places one or two hundred miles, 
and west of the Alleghanies to places four or five hundred 
miles, from their original locality. The following remark is 
important, from its bearing on the Glacial Theory :—-* It is 
very natural to ascribe the smoothness and furrowing of the 
rocks to the action of water. But I have in vain examined 
