Geology and Paleontology. 53 
GENERAL NOTES. 
GEOLOGY AND PALZONTOLOGY. 
On THE THEORY OF GLACIAL Morton.'—As glaciers deport 
themselves like rivers, in that they are constantly flowing, with 
greater velocity at centre than at margins, above than below, form 
pools and rapids, and conform themselves to channels, Prof. Forbes 
was led to propose the theory that: “ A glacier is an imperfect 
fluid or viscous body which is urged down slopes of a certain in- 
clination by mutual pressure of its parts.” ? He explained the veined 
structure of glaciers as being due to differential movement of its 
parts. 
Against this view, it was urged that ice is a brittle solid, which 
in the laboratory cannot be moulded as a semi-fluid, or even in na- 
ture, when in passing over a change of declivity of even 44 degrees, 
it becomes ruptured. Consequently, Prof. Tyndall applied Fara- 
day’s “ Law of Regelation,” è that ice when broken and moistened, 
re-united and could be moulded into any form by repeated crushing 
and pressure, and proposed the “ Fracture and Regelation theory.” 
He explained the veined structure of glaciers as being analogous to 
the slaty cleavage of certain rocks—the result of transverse pres- 
re 
Canon Moseley‘ calculated that the resistance of ice to descent is 
thirty-four times gravitation, and, therefore, fracture and gravitation 
could not be maintained. He likened the motion to the creeping 
of a leaden roof, owing to the expansion and contraction from change 
of temperature, which expansion Dr. Croll’ modified in assuming 
the transmission of heat from molecule to molecule with successive 
liquefaction and solidification of the glacial waters. 
Malleability, plasticity and viscosity are different degrees of the 
Same property. Prof. Heim® distinguishes between these last two 
semi-fluid forms. In plastic bodies, the internal cohesion is less than 
Internal resistance, and, therefore, under pressure these will flow, 
ut under tension they are not drawn out, but are brittle. In vis- 
cous bodies, the internal cohesion is greater than internal resistance, 
and, therefore, they will not only flow under pressure, but in ten- 
Sion they are drawn out before rupture. He concludes that glaciers 
are plastic bodies, and explains the veined structure as being due to 
partial liquefaction under compression in passing through narrow 
By Hoed before the Royal Society of Canada May, 1887, and before the 
~ A. A. B, ely 1887. Printed from advance sheets of Trans. Roy. 
y i 
. Royal Societ : 
5 Climate aaa ie 
sH me. 
andbuch der Gletscherkunde von Dr. Albert Heim, Stuttgart, 1885. 
