220 The Great Ice Age and Origin of the “Till” [April, 
sea and there terminated their existence, just as the 
Antarctic glaciers terminate at the present Antarctic 
ice-wall. 
Whai must happen when a glacier is thus thrust out to 
sea ? This question is usually answered by assuming that 
it slides along the bottom until it reaches such a depth that 
flotation commences, and then it breaks off or “ calves ” as 
icebergs. This view is strongly expressed by Mr. Geikie 
(p. 47) when he says that — “ The seaward portion of an 
ArCtic glacier cannot by any possibility be floated up with- 
out sundering its connection with the frozen mass behind. 
So long as the bulk of the glacier much exceeds the depth 
of the sea, the ice will of course rest upon the bed of the 
fjord or bay without being subjected to any strain or tension. 
But when the glacier creeps outwards to greater depths, 
then the superior specific gravity of the sea-water will tend 
to press the ice upward. That ice, however, is a hard con- 
tinuous mass, with sufficient cohesion to oppose for a time 
this pressure, and hence the glacier crawls on to a depth far 
beyond the point at which, had it been free, it would have 
risen to the surface and floated. If at this great depth the 
whole mass of the glacier could be buoyed up without 
breaking off, it would certainly go to prove that the ice of 
ArCtic regions, unlike ice anywhere else, had the property 
of yielding to mechanical strain without rupturing. But 
the great tension to which it is subjected takes effeCt in the 
usual way, and the ice yields, not by bending and stretching, 
but by breaking.” Mr. Geikie illustrates this by a diagram 
showing the “ calving ” of an iceberg. 
In spite of my respeCt for Mr. Geikie as a geological 
authority, I have no hesitation in contradicting some of the 
physical assumptions included in the above. 
Ice has no such rigidity as here stated. It does possess 
in a high degree “ the property of yielding to mechanical 
strain without rupturing.” We need not go far for evidence 
of this. Everybody who has skated or seen others skating 
on ice that is but just thick enough to “ bear” must have 
felt or seen it yield to the mechanical strain of the skater’s 
weight. Under these conditions it not only bends under 
him, but it afterwards yields to the reaction of the water 
below, rising and falling in visible undulations, demon- 
strating most unequivocally a considerable degree of flexi- 
bility. It may be said that in this case the flexibility is due 
to the thinness of the ice ; but this argument is unsound, 
inasmuch as the manifestation of such flexibility does not 
depend upon absolute thickness or thinness, but upon the 
