But Mr. Campbell himself freely admits that the floating ice which comes aground along the shores does not produce striæ. “It is sufficiently evident,” he says, “_that glacial striæ are not produced by thin bay-ice_” (p. 76). And in “Frost and Fire,” vol. ii., p. 237, he states that, “from a careful examination of the water-line at many spots, it appears that bay-ice grinds rocks, _but does not produce striation_.”
“It is impossible,” he continues, “to get at rocks over which heavy icebergs now move; but a mass 150 miles wide, perhaps 3,000 feet thick in some parts, and moving at the rate of a mile an hour, or more, _appears to be an engine amply sufficient_ to account for striæ on rising rocks.” And in “American Tramp,” p. 76, he says, “_striæ must be made_ in deep water by the large masses which seem to pursue the even tenor of their way in the steady current which flows down the coast.”
Mr. Campbell, from a careful examination of the sea-bottom along the coast, finds that the small icebergs do not produce striæ, but the large ones, which move over rocks impossible to be got at, “must” produce them. They “appear” to be amply sufficient to do so. If the smaller bergs cannot striate the sea-bottom, why must the larger ones do so? There is no reason why the smaller bergs should not move as swiftly and exert as much pressure on the sea-bottom as the larger ones. And even supposing that they did not, one would expect that the light bergs would effect on a smaller scale what the heavy ones would do on a larger.
I have no doubt that when Mr. Campbell visited Labrador he expected to find the sea-coast under the water-line striated by means of icebergs, and was probably not a little surprised to find that it actually was not. And I have no doubt that were the sea-bottom in the tracks of the large icebergs elevated into view, he would find to his surprise that it was free from striations also.
So far as observation is concerned, we have no grounds from what Mr. Campbell witnessed to conclude that icebergs striate the sea-bottom.
The testimony of Dr. Sutherland, who has had opportunities of seeing the effects of icebergs in arctic regions, leads us to the same conclusion. “Except,” he says, “from the evidence afforded by plants and animals at the bottom, we have _no means whatever_ to ascertain the effect produced by icebergs upon the rocks.[142] In the Malegat and Waigat I have seen whole clusters of these floating islands, drawing from 100 to 250 fathoms, moving to and fro with every return and recession of the tides. I looked very earnestly for grooves and scratches left by icebergs and glaciers in the rocks, but always failed to discover any.”[143]