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Proceedings of the Royal Society 
sides of the Butt of Lewis, but I was unable to visit them. I learn 
that Mr James Geikie had not only seen these clay beds, but found 
that some of the shells in them were of an Arctic type. — (See 
Beport, p. 37.) 
There are also in the north part of the Lewis, long ridges and 
high mounds of gravel, sand, and mud, which must have been 
formed by the action of water ; and it deserves notice that some of the 
longest of these kaims run in a north-west and south-east direction. 
In connection with the smoothed rocks, and these submarine 
formations, it is not unimportant to remark that many of the 
boulders must have come at a subsequent period ; for they lie upon 
the striated rocks, and also upon the kaims and gravel mounds. 
Now, the question is whether, in any part of the world, we find 
phenomena analogous to the facts brought out in this Beport? 
In Sir George Bares’ account of his recent Arctic voyage, the 
following account is given by Captain Bielden, the Naturalist of 
the expedition (vol. ii. page 343) : — 
“ Sea-ice moved up and down by tidal action, or driven on shore 
by gales, was found to be a very potent agent in the glaciation of 
rocks and pebbles. The work was seen in progress along the shores 
of the Polar Basin. At the south end of a small island in Black- 
cliff Bay, lat. 82° 30' N., the bottoms of the ‘hummocks, some 8 to 
15 feet thick, were studded with hard limestone pebbles, which 
when extracted from the ice were found to be rounded and scratched 
on the exposed surface only.’ 
“ On shelving shores, as the tide recedes, the hummocks, sliding 
over the subjacent material down to a position of rest, make a well- 
marked and peculiar sound, resulting from the grating of included 
pebbles ivith the rocky floor beneath, or in some cases on other 
pebbles included in drift overlying the rock.” 
Sir George Nares, on landing on Norman Lockyer’s Island, 
found the low part for some 300 feet above the present sea-level a 
succession of raised beaches. “ The rock is composed of Silurian 
limestone. On the summit of a hill 900 feet high, the whole 
surface of the exposed rock is marked with ice scratchings , in a north 
and south direction.” — (Vol. i. page 85.) 
A case exactly parallel is mentioned by Sir Charles Lyell, who, 
when travelling in the Bay of Bundy, North America, fell in with 
