were never reached again after it had retired. I insist upon this point,
because if it is true that all these moraines demonstrate a larger
extent of the glacier, they also prove that their retreat into their
present boundaries, far from having been catastrophic, was marked on the
contrary by periods of repose more or less frequent, which caused the
formation of a series of concentric moraines which even now indicate
their retrogression.

"The remains of longitudinal moraines are less frequent, less distinct,
and more difficult to investigate, because, indicating as they do the
levels to which the edges of the glacier reached at different epochs,
it is generally necessary to look for them above the line of the
paths along the escarpments of the valleys, and hence it is not always
possible to follow them along a valley. Often, also, the sides of a
valley which enclosed a glacier are so steep that it is only here and
there that the stones have remained in place. They are, nevertheless,
very distinct in the lower part of the valley of the Rhone, between
Martigny and the Lake of Geneva, where several parallel ridges can be
observed, one above the other, at a height of one thousand, one thousand
two hundred, and even one thousand five hundred feet above the Rhone.
It is between St. Maurice and the cascade of Pissevache, close to the
hamlet of Chaux-Fleurie, that they are most accessible, for at this
place the sides of the valley at different levels ascend in little
terraces, upon which the moraines have been preserved. They are also
very distinct above the Bains de Lavey, and above the village of Monthey
at the entrance of the Val d'Illiers, where the sides of the valley are
less inclined than in many other places.

"The perched bowlders which are found in the Alpine valleys, at
considerable distances from the glaciers, occupy at times positions so
extraordinary that they excite in a high degree the curiosity of those
who see them. For instance, when one sees an angular stone perched upon
the top of an isolated pyramid, or resting in some way in a very steep
locality, the first inquiry of the mind is, When and how have these
stones been placed in such positions, where the least shock would seem
to turn them over? But this phenomenon is not in the least astonishing
when it is seen to occur also within the limits of actual glaciers, and
it is recalled by what circumstances it is occasioned.

"The most curious examples of per