900 Proceedings of the Royal Society 
gradually melting, allow boulders to obtain these singular lodg- 
ments. 
Of course, if the theory of floating ice be adopted, the position 
of boulders at heights of 3000 feet implies a sea which must 
have stood at that height, or more, above the present sea-level in 
Britain. In that supposition there is no improbability. Moreover, 
beds of sand, mud, and gravel (proofs of marine conditions) actually 
exist in several parts of Perthshire, up to a level of 1500 feet, 1600 
feet, 2000 feet and more {Abstract, pp. 857, 858) ; on Ben Cruachan, 
up to 2000 feet {Abstract, p. 783) j in Glencoe, up to 2000 feet {Ab- 
stract, p. 830) ; and on Schehallion, at a height of 3000 feet 
{Abstract, p. 858). The Ordnance surveyors reported drift beds at 
a height of even 3800 feet {Abstract, p. 831, footnote). Terraces 
on gravel andsand at 1200 feet {Abstract, p. 832). 
In Scotland, sea-shells — and generally of an Arctic type — have 
been found in clay or gravel beds up to a height of about 520 feet 
above sea-level. In several parts of the west of England these 
shells occur in similar deposits up to a height of about 1200 feet, 
and in Ireland (near Dublin) up to a height of 1400 feet above 
sea-level. At the time when the sea stood at either of these 
heights in England and Ireland, it could not with any probability 
have been lower in Scotland. 
Allusion has been made to deflections in the direction of the 
transporting agent, when it struck upon rocks, which slope towards 
certain points, and at different angles. These deflections can be 
understood and accounted for on the supposition of an oceanic 
current with floating ice. Eor by flowing over a rock, which 
obstructed its normal progress, the current might be deflected from 
its usual course. These deflections it would not be easy to explain 
on the theory of solid land ice moving over the country. 
Another circumstance favouring the theory of an oceanic current, 
with floating ice, to account for the movement of boulders, and the 
striation of both boulders and rocks, is the presence of marine shells, 
of Arctic types, in beds of drift containing boulders. In most 
of the cases referred to some of the shells have been crushed, 
whilst others are entire and unhurt. What more probable ex- 
planation can be given of these facts, than that masses of ice float- 
ing on a sea current would, on touching the sea bottom, discharge 
