64 
PROCEEDINGS OE SOCIETIES. 
iceberg began to touch the ground, it would strike it on a surface of 
very small extent at a time. The greater portion of the berg would be 
afloat; and as this, of course, would yield to the action of the waves more 
than the part aground, the result would be a curvilinear motion of great 
irregularity, and subject to constant alteration as the iceberg advanced 
and struck ground in other parts; and even if a portion of it were abso¬ 
lutely afloat, the prominences of the bottom would form temporary 
centres of revolution as it was thrust forward. Prom this I should ex¬ 
pect very great confusion in the tracks of icebergs over an extended area, 
and but little similarity between them and the markings of a glacier on 
dry land, where the even motion is derived from quite different causes. 
The scorings that I have observed in my district correspond with the 
lines of escar hills, and show for many miles an unchanged direction from 
S.W. to 1ST. E. The polished ends of the rocks face the south-west, and 
show that the movement, like the escar drift, proceeded from a quarter 
unfavourable to arctic conditions. Might not the surface strise be referred 
to the rubbing of large flat masses of boulder rocks, which were pushed 
forward by the waves before they became sufficiently rounded to roll ? 
It would be no wonder that the lines, thus engraved, should everywhere 
betray the direction of the single force that caused them, or, in other 
words, be parallel to each other. 
If my reasons for rejecting the floating-ice theory, as applicable to 
the drifts of my district, be considered of any weight, I may object, with 
great confidence, to the land-ice hypothesis. The escar chains bear little 
resemblance to moraines, the character of which I have observed closely 
in the Alps, and the drift that has ascended to higher levels was cer¬ 
tainly not borne on sliding glaciers. 
Still I must not be considered as disputing the possibility, or even 
probability, of the prevalence of a glacial climate here at some compara¬ 
tively modern period of the earth’s history. It is easy to conceive that 
a time may have been when the disposition of land and water in the 
northern hemisphere was similar to what it is at present in the southern, 
and that loaded icebergs may have come down from a great arctic con¬ 
tinent to latitudes even south of Great Britain and Ireland. But what¬ 
ever opinion we may form on this point, my impression is that the drift 
deposits under consideration do not show any structure or phenomena 
which cannot be more easily ascribed to the simple action of water than 
to the agency of those frozen, rafts. We may leave the far-travelled 
erratics of other countries to satisfy the demands of the glacialist; but 
I must claim the formation of at least our Galway and Mayo drifts for 
the liquid force of the ocean; and I will now try to explain how I think 
they could be derived from the force of currents and breakers without 
the intervention of ice. 
I will begin with the u boulder drift,” which I believe was depo¬ 
sited during a sinking of the land. I am aware that Mr. Darwin has 
written on the ascent of hills by boulders; but I have not seen his paper, 
and cannot tell how far his views may agree with or differ from the fol¬ 
lowing :— 
