218 Tertiary. 



caused the strise. Now, I have no hesitation in asserting, from my 

 own observations, as well as from those of others, that for the south- 

 west striation the direction was from the ocean toward the interior., 

 against the slope of the St. Lawrence valley. The crag-and-tail 

 forms of all- our isolated hills, and the direction of transport of bowl- 

 ders carried from them, show that throughout Canada the movement 

 was from northeast to southwest. This at once disposes of the 

 glacier theory for the prevailing set of strise; for we can not suppose 

 a glacier moving from the Atlantic up into the interior. On the other 

 hand, it is eminently favorable to the idea of ocean drift. A subsi- 

 dence of America, such as would at present convert all the plains of 

 Canada and New York and New England into sea, would determine 

 the course of the Arctic current over this submerged land from north- 

 east to southwest; and as the current would move up a slope, the 

 ice which it bore would tend to ground, and to grind the bottom 

 as it passed into shallower water; for it must be observed that the 

 character of slope which enables a glacier to grind the surface may 

 prevent ice borne by a current from doing so, and vice versa. 



Now, we know that in the Post-pliocene period, eastern America was 

 submerged, and, consequentl}^ the striation at once comes into har- 

 mony with other geological facts. We have, of course, to suppose that 

 the striation took place during submergence, and that the process was 

 slow and gradual, beginning near the sea and at the lower levels, 

 and carried upward to the higher ground in successive centuries, while 

 the portions previously striated were covered with deposits swept 

 down from the sinking land or dropped from melting ice. 



The predominant southwest striation, and the cutting of the upper 

 lakes, demand an outlet to the west for the Arctic current. But both 

 during depression and elevation of the land, there must have been a 

 time when this outlet was obstructed, and when the lower levels of New 

 York, New England and Canada were still under water. Then the 

 valley of the Ottawa, that of the Mohawk, and the low country between 

 Lakes Ontario and Huron, and the valleys of Lake Champlain and the 

 Connecticut, would be straits or arms of the sea, and the current, ob- 

 structed in its direct flow, would set principally along these, and act 

 on the rocks in north and south and 'northwest and southeast directions. 

 To this portion of the process, I would attribute the northwest and 

 southeast striation. It is true, that this view does not account for the 

 southeast striai observed on some high peaks in New England; but it 

 must be observed that even at the time of greatest depression, the Arc- 



