SECTIONAL TRANSACTIONS.—C. 385 
adding the effects of Glacial changes of ocean level and temperature, but that 
the modifications thus introduced do not greatly affect the original theory. 
Upgrowth over subsiding foundations still appears to have been the deter- 
mining factor in all barrier and atoll reefs of discoverable origin; the effects 
of Glacial changes of ocean level and temperature appear to be of subordinate 
value as compared to the effects of long-continued subsidence. Inhibition of reef 
growth by reduction of ocean temperature in the Glacial epochs, with a resulting 
low-level abrasion of pre-existent reefs and a cliffing of the islands behind them, 
appears to have taken place in a marginal belt of the Pacific coral seas between 
latitudes 23° and 28° N. and S.; but in the coral seas proper reef growth does 
not appear to have been thus interrupted. Although changes of ocean level are 
believed to have taken place in the Glacial Period, it has not been possible to 
determine their amount by their effects. 
(c) Prof. A. P. Coreman, F.R.S.—Raised Beaches as Related to the 
Thickness of Ice Sheets. 
Raised beaches occur in eastern, northern, and western Canada, and the 
amount of elevation of such beaches above sea-level appears to be roughly 
proportional to the thickness of ice removed at the end of the Glacial Period, 
thus supporting the theory of isostatic equilibrium. 
Instances are given showing these relations in Ontario, Quebec, the Maritime 
Provinces, Newfoundland and Labrador. 
General Discussion. 
14, Prof. W. M. Davis.—An Uptilted and Bevelled-off Atoll. 
If an atoll, thirty miles in diameter, were uptilted by deformational forces 
so that about half its area were raised above sea-level with a slant of 15°, and 
then bevelled off by degradational processes, its understructure would be well 
revealed. If the atoll had been built up over a subsiding foundation according 
to Darwin’s theory, the revealed understructure should exhibit a rock series 
of a considerable thickness, including volcanic rocks of subaerial eruption at 
the base, and marine calcareous beds above; the latter should contain corals and 
other fossils indicative of deposition in shallow water. An island of this kind 
will be described, in which the thickness of the bevelled-rock series is about 
five times the depth of the Funafuti boring. 
15, Prof. J. W. Russenu.—Hvidences of a quite recent Extinction of 
the American Mastodon. 
(1) Most Mastcdon remains have been recovered from post-glacial bogs con- 
taining either peaty material or marl, which acted as a preservative, thus 
obscuring the time interval. 
(2) During the past two years three places containing Mastodon skeletons 
were visited ; one of these had neither marl nor peat as a preservative. 
(3) Description and views of this location and samples of the bones found 
will be given; also description of the rapid weathering and dissolving that 
would have occurred here. 
16. Mr. Leversrr.—Glacial Phenomena in Kentucky. 
17. Mr. L. D. Huntoon.—Gold Production in Canada. 
18. Dr. H. M. Am1.—Paleozoic Problems in Eastern Canada. 
19. Mr. C. F. Ketiy.—Mineral Detection by means of its Electrical 
Activity 
1924 CC 
