310 Rogers’s Account of two Remarkable 
Art. XXIII. — AN ACCOUNT OF TWO REMARKABLE TRAINS OF 
ANGULAR ERRATIC BLOCKS, IN BERKSHIRE, MASSACHUSETTS, 
WITH AN ATTEMPT AT AN EXPLANATION OF THE PHENOMENA. 
By Pror. Henry. D. Rogers and Pror. Wittram B. Rocers. Read Dec. 3, 
1845. 
Tue origin of the drift or diluvium, that extensive, super- 
ficial stratum of loose, fragmentary, rocky materials, which 
covers, in one unbroken sheet, the northern portions of both 
continents, from the highest latitudes explored to the parallel 
of the Alps, in Europe, and to 40° or 41°, in North America, 
has, for many years past, been one of the most interesting 
questions in geological dynamics. 
In the recent discussion, which it has received from some 
of the most eminent of the cultivators of science, on both sides 
of the Atlantie, this question has been shown to involve an 
inquiry into the nature and mode of action of nearly all the 
great physical agents concerned in the revolutions of the 
earth's surface, the transportation of soil by icebergs, the 
pushing forward of moraines by glaciers, and the more rapid 
strewing of débris by violent continental inundations. 
It connects itself, therefore, with investigations into the 
former climates of the world, and into the changes in the dis- 
tribution of its lands and waters, and it, consequently, requires 
a knowledge of the great secular and paroxysmal disturbances 
in the earth's crust, from whence these and all the other sur- 
face revolutions have proceeded. 
The object of the present brief paper is not so much to 
present our views of the whole train of causes explanatory of 
the origin of the drift, —a discussion which would lead to ? 
wide investigation into the efficacy of nearly all the physical 
agents and changes above referred to,— but it is simply xf 
test, by certain unexplained phenomena, the relative merits © 
the several hypotheses of drift-action, most in favor with geo- 
logists. 
The phenomena, to which we here allude, are those of 
