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98 THE EXPLORATION OF THE CAUCASUS
were carried down by the raging torrent. The origin of the
mischief" has never, however, been autlioritatively or exactly
explained. The sudden bursting of a sub-glacial lake, as in the
St. Gervais catastrophe, the creation and subsequent desti'uction
of a dam, caused by the fall of an avalanche from some lateral
ravine across the glacier torrent ; these are among the obvious
hypotheses that have been brought forward. But the bursting of
a sub- glacial reservoir is, in the Alps and elsewhere, a very rare
event. The Kasbek disaster, early in the present century, was of
frequent recurrence, and was believed to recur at periods of seven
years. There should, therefore, be something exceptional in the
local conditions. Now, as every experienced mountain explorer
will note on looking at the photograph here reproduced, the
peculiarities of the Devdorak Glacier are its narrowness, steepness,
and thickness. The terminal slope is of almost unparalleled height.
Is it not probable that the upper and central layers
of ice, moving
faster than the lower
according to the law that governs glaciers,
the cave
layers, sheer over and fall, temporarily burying and blocking
from which the stream issues ? Such accounts as I have found
of the conditions preceding a flood speak invariably of an advance
of the glacier, and assume it to be the main cause. Dr. Abich
expressly attributed the disaster to a fall in the front of the glacier.
I put forward, however, this suggestion tentatively. Further local
inquiries are very desirable. Bad weather has prevented me from
making any detailed examination of the ground myself, but those
who desire to do so can now obtain lodging in a house, erected
by the Government near the foot of the glacier.
Two glens, those of the Lagzdon and Gezeldon, run up to the
northern glaciers of Kasbek and its neighbour Gimarai Khokh, a
summit of the height of Mont Blanc. For a full description of
them the reader must turn to the forthcoming volume of Herr
Merzbacher, who was successful in scaling Gimarai Khokh, and also
Kasbek, from this side.
Close to the glacier at the head of the former glen the German
traveller found a curious and primitive bathing establishment.
It consists of a few rude stone huts, grouped
round a mineral