Chapter XXII

Summary

I had frequent opportunities in the valley of the St. Lawrence, especially at Kingston, and in the country between that city and Gannanoqui, of examining the recently bared surface of the fundamental rocks, consisting of, first, granite; 2dly, quartzose (or Potsdam) sandstone; 3dly, lower Silurian (or Trenton) limestone. Wherever the drift or superficial clay and gravel have been removed, the surfaces of these rocks are worn, smoothed, and furrowed, the furrows being least clearly defined on the sandstone.

The direction of all the straight and parallel grooves was nearly N. E. and S. W., differing uniformly in their general course from those traced by Professor Hitchcock and Mr. Percival through New England, where they run usually from N. N. W. to S. S. E. It is worthy of notice, that in both regions the erratic blocks and boulders have been transported southwards, along the same lines as are marked out by the direction of the furrows. There is obviously, therefore, a connection between these two distinct classes of phenomena; and I know of no theory that can account for both of them, with any plausibility, except that already alluded to in the last chapter, viz. the agency of large islands of floating ice, which, by their buoyancy and enormous weight, supply the carrying power and pressure required to scratch, polish, and groove the solid floor of the ocean, and to convey stones of all sizes, firmly fixed and frozen into the ice, to great distances.