Dr. Hitchcock on some Phenomena of Drift. 263 
Nor is the size of the individual blocks small. They are usually 
some feet in diameter, and now and then we meet with examples 
of extraordinary magnitude. At the foot of the hill, northwest 
of Richmond meeting-house, is the largest I saw. It is 140 feet 
in circumference, and 12 feet thick. A rod or two distant lies a 
fragment, which has been detached from the main block, which 
is 19 feet long, 20 feet broad, and 54 feet thick. These two 
blocks, originally one, contain 16,000 cubic feet, and weigh about 
1,370 tons. Ihave seen others as large nearly ; but in several 
instances they were split into pieces, as if they had fallen from 
a considerable height into their present position. 
Such are the facts. What inferences can we draw from them? 
In the first place, these trains of blocks must have been scat- 
tered during the latter part of the drift period, and by the same 
general agency that accumulated the rounded detritus beneath 
the blocks, and smoothed and furrowed the rocks. The fact 
that the trains of blocks lie upon the surface above the common 
drift, proves that they were brought there by an agency more 
recent than that which accumulated the inferior detritus. But 
as the force acted in both instances in the same direction, that 
is, southeasterly, and must. have been very different from any 
other agency that has since acted in that region, we have no 
good reason for calling in other powers to explain effects so 
nearly alike. 
In the second place, it is impossible to explain this case by any 
theory of drift, which refers it to the agency of currents of water 
alone, or of the water and the detritus driven along by its power. 
The very oblique direction which the train takes across high 
ridges, would alone refute the idea that water could have done it, 
even though the whole northern ocean had rushed with the 
violence of a descending cataract over the spot. But still more 
absurd does such an hypothesis appear, when we learn that thou- 
sands of blocks are strewed over a distance of fifteen miles, not 
the eighth of a mile in width, and preserving an uniform direction. 
He who can suppose that a current of water would thus confine 
such a train of blocks,—some of them of enormous weight,— 
within such narrow and exact limits, and that too without wear- 
ing off the angles of the blocks, must have a very different idea 
of the dynamics of currents of water from what I have. 
