285 
PSOFESSOE TYNDALL ON THE VEINED STEUCTUEE OF GLACIEES. 
hollows between them wrinkle up in submission to the pressure ; the whole aspect of 
the glacier here gives evidence of the powerful exertion of the latter force ; and exactly 
at the place where it is exerted, the structure makes its appearance, and being once 
manufactured, is sent onwards, giving a character to other portions of the ice-stream 
which have no share in its production. 
An illustration, perhaps equally good and equally accessible, is furnished by the 
glacier of the Rhone, Above the great icefall which the traveller descending from the 
Furca has to his right, the horizontal bedding is exhibited in a more or less perfect 
manner, to a certain depth, upon the walls of the huge and numerous crevasses here 
existing. I have also examined this fall from both sides, and an ordinary mountaineer 
will find no difficulty in reaching a spot nearly opposite the centre of the fall, from 
which both the fall itself and the glacier below it are distinctly visible. Here a similar 
state of things to that already presented to his view reveals itself. The fall is structure- 
less ; the cliffy ridges are separated from each other by transverse hollows, following 
each other in succession down the slope ; those ridges are toned down to protuberances 
at the base of the fall, becoming more and more subdued, until low down the glacier 
the transverse swellings disappear. As in the case of the Grindelwald glacier, the 
squeezing of the protuberances and of the spaces be- 
tween them is visibly manifested. Where this squeezing 
commences the transverse structure also commences, and 
in a very short distance reaches perfection. All the ice 
that forms the lower portion of the glacier has to pass 
through this structure mill at the base of the fall, and the 
consequence is that it is all laminated. 
The case will be better appreciated by reference to 
figs. 3 and 4, the former being a sketch, in plan, and 
the latter a sketch in section of a part of the ice-fall and 
of the lower portion of the glacier of the Rhone, aehf 
is the gorge of the fall, and f b its base. The transverse 
ridges are shown crossing the fall, being subdued at the 
base to protuberances, which gradually disappear further 
down the glacier. The “ structure ” sweeps across the 
glacier in the direction of the fine curved lines. On 
the plan I have also endeavoured to show the radial 
crevasses of the glacier; they are at right angles, or 
nearly so, to the structure. As would be inferred by 
those acquainted with what I have already written upon 
the influence of curvature, the side b c d o{ the glacier is much more violently crevassed 
than the sidey^A. 
Fig. 4 shows the cliffy ridges of the fall, and of the rounded protuberances below it, 
in section. The shading lines below denote the structure. The protuberances are so 
MDCCCLIX. 9 r. 
Fig. 3. 
