562 British Association Reports. 
bably derived from fields of ice grounded in the shallows, and 
there depositing their rocky burden. 
4. Recent Boulder-drift.—The driftage of the boulders in the 
Gulf of St. Lawrence was next noticed, and the author states that 
it would only require a subsidence which would bring these boulders 
under the influence of muddy deposits to form a sort of Boulder- 
clay. 
3. Supposed Drift by Glaciers.—With regard to the striations on 
the shore of Lake Huron, &c., and in Labrador, referred to the 
action of land-ice by Sir W. Logan and Professor Hind, Dr. Dawson 
admits that the mean temperature of Canada may have been so 
reduced by the diminution of land surface and the influx of cold 
currents loaded with ice, to permit the existence of glaciers in some 
of the hilly regions; but he rejects the theory that Canada was at 
any time covered with a general or universal glacier as physically 
impossible, and assigns his reasons in a quotation from a previous 
paper, to the effect that most of the striations are due to icebergs, 
and that many of the so-called moraines are probably shingle beaches, 
and old coast lines loaded with boulders. 
Part II. On Movern Icrsercs.—This is an account of obser- 
vations recently made on the icebergs in the Strait of Belle Isle. 
Between Newfoundland and Labrador, a branch of the Arctic 
current enters the strait at the north, bringing about one-fifth of 
the bergs that are drifted down the Labrador coast; as many as 496 
bergs have been counted in the strait at one time, many 60 feet 
in height, some more than 200 feet. The bottom of the strait con- 
sists of rocks and stones in most parts; and as the majority of the 
bergs had grounded, it is evident that the abrading power exercised 
by them was enormous, far greater than that of any glacier in a 
single year. Other icebergs, 400 feet high and half a mile long, 
have grounded off the strait, which, urged on by the current, and 
swaying to and fro, would constitute abrading agents unequalled in 
power. One berg noticed by Dr. Dawson had been overturned, and 
displayed what had been its working surface flattened and scored. 
The author infers that no other agency than icebergs, reinforced by 
glaciers descending from the higher lands of Labrador, need be 
invoked to produce ali the glacial effects observed in the Valley of 
the St. Lawrence, and that these observed phenomena correspond 
much better than that of a mantle of glacier, the possibility of 
which, on physical grounds, is more than doubtful. 
Part III. On tHe Post-pLioceneE PLants.—In this paper, Dr. 
Dawson describes the species of plants found in the Post-pliocene 
deposits, and shows what light they throw on the climate and geo- 
graphical conditions of the period. ‘They were principally obtained 
from nodules in the Leda-clay, associated with Leda truncata, and 
seem to have been washed down from the land into deep water. 
They indicate a summer colder than the present, to an extent equal 
to about 5° of latitude, which concurs with the other evidence the 
author has obtained, that the refrigeration of Canada in the Post- 
pliocene period consisted in a diminution of the summer heat, and 
