PHYSICAL FEATURES OF NOVA SCOTIA.—MURPHY. 133 
visible along the valley of the Rhone for a distance of 80 miles. 
until lost in Lake Geneva, are due to the same cause. For, says 
the learned Doctor, “ Grand as the present glaciers seem to those 
who explore them to their full extent, they are mere pigmies in 
comparison with their predecessors.” By their predecessors he 
means, as expressed previously, traces of ancient glaciers. 
There are many theories for the cause of glacier motion. 
1. That of Dr. Saussure,—The slow but continual sliding of 
the icy masses on inclined bases. 
2. The dilation theory, from expansion of water accumulating 
daily in its fissures, tending to urge the glacier onwards. 
3. Then there is that of Professor Forbes, viz:—A glacier is 
an imperfect fluid or viscous body which is urged down slopes 
of a certain inclination by the mutual pressure of its parts. 
The Encyclopedia Britannica, after giving in its usual preci- 
sive style, a description of the glacier, concludes its last paragraph 
on the subject thus:—“The problems of the cause of glacier 
motion cannot yet be considered to be satisfactorily solved,” and 
goes on to quote the contributors on the subject; such as Professor 
James Thompson, Professor Forbes, Sir William Thomson, Tyn- 
dall, Faraday and others, ending with the views of‘Dr. Croll, who 
_ regards the motion of ice of a glacier as molecular, resulting from 
the very conduction of heat through the mass of the glacier, 
which will melt the ice and create a wave of thaw, but will in turn 
freeze again and cause a downward movement in the direction 
which has the least resistance, and the direction in which gravi- 
tation co-operates. 
If we take a broad view of the extent of surface which exhibits 
such markings as those under consideration, we ean scarcely 
admit the theory of a gradual subsidence and the re-elevation 
with the action of the sea and its currents bearing ice at certain 
seasons of the year, which is really that of Dr. Dawson. 
The slope running back from the south-eastern shore to the 
top of the ridge of the low mountain range all the way from Cape 
Canso to Cape Sable, although rugged, undulatory and serrated, 
in numerous places, is nevertheless free from very high protu- 
berances, 
