BY R. M. JOHNSTON, F.L.S. 121 
glacial epoch of Europe, in any part of the lowlands of even 
the most southerly region of the Australian mainland, at 
least. These conclusions are in perfect harmony with the 
most recent investigations of the extent and comparative 
intensity of the glaciation of Europe in the last ice age. 
Perhaps there is no one entitled to speak with greater 
authority on such a matter as Prof. James Geikie, D.C.L., 
LL.D., F.R.S., the accomplished author of “ The Great Ice 
Age.” In his last presidential address* to the members of the 
Geological Society of Edinburgh—from which I am proud to 
have received the honour of being elected as one of the 
honorary foreign corresponding members—he deals with the 
whole of the “Supposed Causes of the Glacial Period” with 
amaster mind. In referring to the extent of knowledge 
now possessed by us in measuring the limits and intensity 
of glaciation of the “ Ice Age,” he statest :—‘‘So greatly has 
our knowledge of the Glaciation of Hurope increased during 
recent years, that the height of the snow line of the glacial 
period has been determined by MM. Simony, Partsch, 
Penck, and Hofer. Their method is simple enough. They 
first ascertain the lowest parts of a glaciated region from 
which independent ‘glaciers have flowed. This gives the 
maximum height of the snow line. 
“Next they determine the lowest point reached by such 
glaciers. It is obvious that the snow line would occur higher 
up than that, but at a lower level than the actual sources cf 
the glaciers, and thus the minimum height of the former 
snow line is approximately ascertained. 
“The lowest level from which independent glaciers formerly 
flowed, and the terminal point reached by the highest lying 
glaciers having been duly ascertained, it is possible to 
determine with sufficient accuracy the mean height of the old 
snow line. The required data are best obtained, as one might 
have expected, in the Pyrenees and amongst the mountains of 
MIDDLE and SOUTHERN Hurope. 
“ In those regions the snow line would seem to have been some 
3,000 feet or so lower than now! From such data Professor 
Penck has constructed a map showing the isochional lines of 
the glacial period. These lines are, I need hardly say, only 
approximations, but they are sufficiently near the truth to 
bring out the contrast between the ice age and the present. 
Thus the isochional of 1,000 metres which at present lies 
above Northern Scandinavia was pushed south to the latitude 
of Southern France and North Italy ; while the isochional of 
2,000 metres (now overlying the extreme North of France 
* Trans. Edinburgh Geol, Soc., Vol. VI., Part 3, pp. 209, 230, 
t Ibid., p. 211. 
