:28 THE CANADIAN NATURALIST. [^^l. 



VI, 



in New England, the prevailing direction is South Eastward, 

 though there are also South-west and South striation, and a few 

 cases where the direction is nearly East and West. 



It is obvious that such striation must have resulted from the 

 action of a solid mass or masses of ice bearing for a long time on 

 the surface and abrading it by means of stones and sand. It is 

 further obvious that the different sets of striation could scarcely 

 have been produced at the same time, especially when, as is not 

 infrequent, we have two sets nearly at right angles to each other 

 isi the same locality. Hence it becomes an important question 

 to a^ertain the relative aa^es of the striation and also the direc- 

 ti(m in which the abrading force moved. 



Taking the valley of the St. Lawrence in the first instance, the 

 (crag-and-tail forms of the isolated hills of trap, like the Montreal 

 mountain, with abrupt escarpments to the north-east and slopes 

 ■of debris to the south-west, the quantity of boulders carried from 

 them far to the south-west, and the prevailing striation in the 

 same direction, all point to a general movement of detritus up 

 the St. Lawrence valley to the south-west. Further, in some 

 cases the striae themselves show the direction of the abrading 

 force. For example, in a fine exposure recently made at the 

 Mile-end quarries, near Montreal, the polished and grooved sur- 

 face of the limestone shows four sets of striae. The principal 

 ones have the direction of S. 6S^ W. and S. 60*^ W respectively, 

 and the second of these sets is the stronger and coarser, and some- 

 times obliterates the first. The two other sets are comparatively 

 few and feeble striae, one set running nearly N. and S., and the 

 (Other N.W. and S.E. These last are probably newer than the 

 two first sets. Now with regard to the direction of the principal 

 sets of striae, this at the locality in question was rendered very 

 manifest by the occurrence of certain trap dykes crossing the 

 limestone at right angles to the striae. The force, whatever it 

 was, had impinged on these dykes from the N. E., and their 

 S. W. side had protected the softer limestone. The locality is to 

 the North-east of the mass of trap constituting the Montreal 

 mountain, and the movement must have been up the St. Law- 

 rence valley from the N.E., and toward the mountain, but at this 

 particular place the striae point West of its mass. This, I have 

 no hesitation in saying, is the dominant direction in the St. Law- 

 rence valley, and it certainly points to the action of the arctic 

 current passing up the valley in a period of submergence. Fur- 



