Ch. Xn.] GLACIAL SCORIXGS ON SCOTTISH ROCKS. 155 



a great portion of this drift rniglit be connected with the severity of 

 the cold, and also in some places with the depth of the sea during 

 the period of extreme submergence ; but my faith in such an hypo- 

 thesis has been shaken by modern investigations, an exuberance of 

 life having been observed both in arctic and antarctic seas of great 

 depth, and where floating ice abounds. Tims, Dr. Hooker enume- 

 rates erustacea, mollusca, serpulae, and other invertebrata, at depths 

 of 200 and 400 fathoms off Victoria Land, between latitudes 71° and 

 78° S., and animal life was traced even to a depth of 550 fathoms ; 

 whilst MM. Torell and Chydenius in 1861 obtained mollusca, between 

 Spitzbergen and Norway, at the enormous depths of 1000 and 1500 

 fathoms, the temperature of the mud being between 32° and 33° 

 Fahrenheit. 



We have seen that the scoring and polishing of the rocks in Scot- 

 land, as in Sweden and elsewhere, is not confined to the land, but is 

 seen to pass under the sea, the same farrows being so continuous as 

 to imply that glaciers or continental ice once acted on a surface now 

 submerged. Mr. Geikie observes that, on the west coast of Scotland, 

 these glacial markings are almost always fresher at and below the 

 present sea-level than at higher levels. In some places, even where 

 the ice-moulded rocks are washed by the waves of the sea, they retain 

 then finer striae, and bosses of rock their rounded and smoothed sur- 

 faces. Yet, at an elevation of 20 feet and upward, the rounded out- 

 lines are broken, and all the exposed surfaces disintegrated by the 

 water. In explanation of these peculiar appearances, he supposes, 

 first, the sinking of land which had been polished and striated by 

 continental ice in the manner before alluded to, p. 144 ; secondly, a 

 very recent date for the upheaval of the lowest 25 feet of the coast, a 

 suggestion confirmed by the occurrence of a raised beach in which 

 the recent shells agree with those of the adjoining sea, and indicate a 

 less glacial climate than those of an older beach found at a higher 

 level, or about 40 feet above high-water mark. The upper of the two 

 beaches has suffered more from atmospheric action than the lower, 

 and has evidently been exposed for a much longer time. 



Besides the proofs afforded by shells at the height of about 500 

 feet, there are also on the mountains of many parts of Scotland, as, 

 for example, on the Grampians, and on the Sidlaw and Pentland 

 Hills, erratic blocks, at heights from 1000 to 2000 feet and upward, 

 so wholly unconnected with the mineral structure of the region where 

 they lie, that they seem to point to a former period of submergence 

 and floating ice. There is also another curious phenomenon bearing 

 on this subject which the late Hugh Miller styled the striated "pave- 

 ments " of the boulder clay. "Where portions of the till have been 

 removed by the sea on the shores of the Forth, or in the interior by 

 railway cuttings, the boulders imbedded in what remains of the drift 

 are seen to have been all subjected to a process of abrasion and stria* 

 tion, the strise and furrows being parallel and persistent across them 



