SUPERFICIAL DETRITUS. 
325 
been moved forward over the surface with resistless force, and, in their passage, uplifting, 
breaking and transporting the fragments of strata over which they pass. That blocks of 
granite, either enclosed in ice or moved by other means, have been the principal agents in 
effecting diluvial phenomena; that they have scored and grooved the rocks in their passage, 
and breaking up the strata, and mingling themselves with the mass, have been driven onward, 
carrying everything before them in one general melee. That such may have been the case 
in some instances, or in limited localities, cannot be denied ; but that it ever has been over 
any great extent of country, will scarcely admit of proof.* 
A glimpse of a more rational explanation has occasionally offered itself, and after an exami¬ 
nation of my notes, and the numerous sections made on the spot, I have found, almost univer¬ 
sally, that they correspond with the preceding sections and their explanation, viz. a bed of 
broken fragments, with worn pebbles resting upon the rock from which they are derived. 
The granite and other materials of a far northern origin rarely constitute a part; and I am 
not prepared to say that, in any instance where they do form a part, the deposit has not under¬ 
gone some subsequent change. 
If we adopt the views indicated by the facts here presented, it does not preclude the proba¬ 
bility of deposits of purely northern origin (containing rocks of granite, gneiss, etc.) from 
resting directly upon any other stratified rock; for even allowing the earliest drift to have 
been formed by the wearing of the ocean and the breaking up of the strata by the action of 
waves, still all this may have been subsequently removed, and another deposit have taken its 
place. Such, doubtless, has often happened; and if a previous deposit is removed to make 
room for another, then we should naturally expect, in many instances, a mingling of the two. 
Grooved, striated and polished rocks. 
Intimately connected with the subject of the older drift is that of grooves, or striae upon the 
surface of strata which lie immediately beneath. All the rocks of the Fourth District which 
are of a sufficient hardness to receive and retain such impressions, and which have since with¬ 
stood the action of the weather, are more or less marked in this manner. From the Medina 
sandstone, at the level of Lake Ontario, to the summit of the conglomerate of the Carbonife¬ 
rous system, some of the strata in every group bear upon their surfaces these markings of 
former abrasion and the evidence of moving force. These, too, for the most part, bear a very 
uniform and decided direction, varying but a few degrees from N. 35° E. and S. 35° W. in 
their general course. Short and shallow striae are abundant, which vary ten and fifteen de¬ 
grees from this direction; but these have no continuous course, and apparently fall into the 
main direction after a few feet. 
* In primary regions there are no other rocks than granite, gneiss and their associates ; and consequently whatever may be the 
age, or by whatever means produced, the superficial deposits are charged with these masses. 
