GENERAL .MEETING. 37 
There followed a symposium on the question 
WHAT IS A GLACIER? 
[ Abstract. ] 
Mr. I. C. Russevu: In framing a definition of a glacier it is 
evident that we must include both alpine and continental types, 
and also take account of the secondary phenomena that are com- 
monly present. With this preamble we may define a glacier as an 
ice-body, originating from the consolidation of snow in regions 
where the secular accumulation exceeds the loss by melting and 
evaporation, 7. ¢., above the snow-line, and flowing to regions where 
loss exceeds supply, 7. e., below the snow-line. 
Accompanying these primary conditions, many secondary phe- 
nomena dependent upon environment, as crevasses, moraines, lami- 
nation, dirt-bands, glacier-tables, ice-pyramids, etc., may or may 
not be present. 
Mr. 8. F. Emmons: The glacier is a river of ice, possessed, like 
the aqueous river, of movement and of plasticity. In virtue of 
the latter quality it adapts itself, though more slowly, to the form 
of the bed in which it flows. The névé field is the reservoir, from 
which it derives not only its supply of ice, but the impulse which 
gives it its first movement. The névé is formed by the snows which 
accumulate in relatively wide basins above the snow-line from 
year to year, living through the heat of summer. Its mass may be 
more or less compact, according as it is thicker or thinner, and it 
may have a certain movement, which will be greater or less, accord- 
ing to the greater or less inclination of the basin; but until it moves 
from its wide and shallow bed into a narrower and deeper one, and 
thus gives outward proof of the plasticity of the ice of which it is 
composed, it does not become a glacier. It may be crevassed. 
Often a long crevasse at its upper edge gives definite proof of its 
movement; and this movement may cause a cracking or crevassing 
in other points, resulting from the unevenness of its bed. It may 
or may not carry blocks of rock on its surface, but these would be 
rare, and never in the well-defined moraine ridges that are formed 
upon the glacier proper. Not, however, until its form had essen- 
tially changed to fit the bed in which it flows should it be considered 
to ee a glacier proper. 
