496 Mr. J. Ball on the Structure of Glaciers. 
subsist long enough, be converted into glacier, Thus we often 
have névé beds, and may easily find glacier, formed upon an un- 
derlying glacier at a place far removed from that where the lower 
part was originally consolidated. In such cases, one instance of 
which is described at page 204 of the Nouvelles Etudes sur les 
Glaciers, 1t is obvious that no sort of conformity can be ex- 
pected to exist between the structure of the upper and the lower 
beds. When, either through a temporary change of seasons, or 
through the descent of the newly-formed glacier or névé beds 
into a warmer climate, these latter begin to waste away, this 
process will usually go on most rapidly along the outer edges of 
the new deposits, and especially where adjacent rocks reflect 
heat upon the glacier, and the same operation may easily cut 
into the underlying mass of old glacier. In this way we may 
have exposed to view layers of dirt and debris of rock, either 
underlying the new formation, or intercalated between its beds 
during the period of its growth, but having no relation what - 
ever to the surfaces which indicate the structure and mode of 
formation of the old glacier. When the new formation is com- 
pletely melted away, no difficulty remains, because the whole of 
the foreign matters mixed up in it will be deposited on the sur- 
face of the main glacier, now again brought to light, and will 
follow the ordinary laws which regulate the distribution of su- 
perficial debris. 
5. Crevasses. 
6. Capillary fissures. 
7. Air-bubbles. 
This paper has grown to such undue length, that I forbear to 
add more than a single remark upon these topics to those which 
I have included in the foregoing pages. 
It seems to me, that in regard to the existence and extent of 
capillary fissures in the compact ice, those portions of a glacier 
which are subjected to the pressures and tensions which must 
accompany the onward movement of the mass, may be expected 
to be in a different condition from those which by their position 
are excmpted from the action of these forces. Parts of the ice 
sometimes appear completely solid, and show to the eye no trace 
of capillary fissures. Perhaps the existence of these is not so 
universal as has been commonly supposed. 
I may now be permitted to point out very briefly how far 
the facts discussed in the foregoing pages are consistent with a 
theory of glacier structure which has hitherto found little favour 
with the eminent men who have taken part in the controversy. 
According to this hypothesis, the stratification of the névé passes 
by a gradual consolidation of the ice into that laminar or veined 
re 
