From what has been already stated in reference to
the i-e-solidifying of the particles in the interstices of
the ice, the application of the theory to the explanation
of the effects under consideration will no doubt be
apparent. Take the case of the passage of the ice-
sheet across a river-valley. As the upper surface of
the ice-sheet is constantly receiving heat from the sun
and the air in contact with it, there is consequently a
transference of heat from above downwards to the
bottom of the sheet. Tliis transference of heat is
accompanied by the melting and re-solidifying of suc-
cessive particles in the manner already detailed. As
the fluid particles tend to flow into adjoining inter-
stices before solidifying and assuming the crystalline
form, the interstices of the ice at the bottom of the
valley are constantly being filled by fluid particles
from above. These particles no sooner enter the inter-
stices than they pass into the crystalline form, and
• See 'Climate and Tinie,' p. B26,



256



DISCmSIOKS IS CLIMATOLOGY.
