BY R. M. JOHNSTON, F.L.S. 93 
tion to a personal friend of my own,* and one of his early 
associates, that I first, about 20 years ago, became aware of 
his discovery of many evidences of glaciation in Tasmania, 
especially in the valleys of the western highlands, which 
trend westward from the great elevated plateau of 4,000 to 
5,000 feet level, which occupies an area of some 400 square 
miles in the centre of our heart-shaped island. On its 
northern and western sides this elevated plateau rests upon a 
less elevated but still more extended plateau, whose undula- 
tions preserve a general level of from 2,000 to 8,000 feet above 
the sea. The extreme western and southern part of the 
island presents a wild and broken array of lofty mountain 
ranges and isolated peaks, with deeply cut ravines and 
valleys, but whose bases rest generally upon lower levels than 
the western portion of the massive central plateau. Although 
Tasmania does not possess any mountains of great altitude, 
its mountainous character may be best realised when we 
consider that within its limited extent (26,215 square miles) 
there are 20 names of mountains over 4,000 feet in height, 
and as many as 50 named mountains whose heights exceed 
2,500 feet. 
The large inland plateau which maintains a general alti- 
tude of about 4,000 feet, rising at times to over 5,000 feet, 
is worthy of special attention when regarding the conditions 
necessary for the development of a sufficiently large per- 
manent snowfield, which would suffice to feed glaciers flowing 
from its marginal slopes, during a period of extremely low 
temperature; for great height or extremely low temperature, 
per se, does not constitute all the necessary conditions for the 
development of glaciers. 
We must also conjoin with either of these conditions 
breadth of area of the névé or snow catchment, and a great 
local precipitation of water vapour. The necessary combina- 
tions of these requisite conditions are not dreamt of by many 
who too readily invoke glacial action within the Tertiary or 
Pleistocene period in regions where it is difficult to realise the 
full combination of the essential conditions necessary for its 
production. 
The following description, already given by me in a former 
publication,+ may help to afford the necessary information to 
those who may wish to know whether, in the event of a greatly 
lowered temperature, due to astronomical or other causes, 
the great inland plateau of Tasmania possesses all the other 
requisite conditions for the generation of glaciers :— 
“The great central greenstone plateau of the Lake Country 
* The Hon. Jas. Reid Scott, formerly Chief Secretary of Tasmania. 
tGeology of Tasmania, p. 101. 
