193 
XII. 
ICE OBSERVATIONS. 
By Proressor J. W. Grecory. D.Sc. F.R.S. F.G.S. Assisted by 
Proressor T. G. Bonngy, D.Sc. LL.D. F.R.S. F.G.S.* 
Memepers of the Expedition will have ample opportunities for the 
observation of Antarctic ice, but, that the observations may be scienti- 
fically useful, they must be systematic, and directed along certain 
definite lines. The following notes suggest lines of enquiry and a 
few explanations as to their objects. 
The great ice fields of the world may be divided into three groups. 
(1) Land ice—fields of snow and sheets of ice, and their tributary 
glaciers, which act as ice rivers, discharging the surplus snowfall from 
the collecting grounds to lower levels. (2) Icebergs—blocks of ice 
which have been detached from glaciers where they reach the sea or 
lakes. (3) Ice floes—comparatively thin sheets which have been 
formed in circumpolar regions by the freezing of the sea. 
In the Antarctic regions representatives of each group will be 
found, and probably will be developed on a greater scale than in any 
other part of the globe. But the study of Antarctic ice is desirable, 
not only from its local geographical importance, but also from the 
evidence it may yield as to the conditions of the period when some 
form of ice agent deposited a vast sheet of clay, sand and gravel over 
much of North-western Europe, including most of the British Isles, 
and over Canada and the northern part of the United States. 
There has been a prolonged controversy as to the mode of forma- 
tion of these deposits, but the main question is now reduced to the 
alternatives, (1) that vast continuous sheets of ice covered most of 
Northern Europe and America, just as its ice-cap does Greenland ; or, 
that there was a series of local glacial centres, beyond the limits 
* As Professor Gregory was obliged to return to Australia before quite completing 
these notes, he posted the manuscript to me, with the request that I would revise it, 
adding anything which I thought desirable, and see it through the press. I have 
accordingly made a few verbal alteratiuns and added an occasional sentence or 
clause.—T. GU. B. 
QO 
