he advance of the latter to the
north. The anticline has advanced relatively to the syncline. To
this law one exception only is observed in the Swiss Alps; the
sheet of the Breche (_Byecciendecke_) falls short, in its northerly
extension, of the underlying fold, which extends to form the
Prealpes.

Contemplating such a generalised section as Professor Schmidt's,
or, indeed, more particular sections, such as those in the Mont
Blanc Massif by Marcel Bertrand,[1] of the Dent de Morcles,
Diablerets, Wildhorn, and Massif de la Breche by Lugeon,[2] or
finally Termier's section of the Pelvoux Massif,[3] one is
reminded of the breaking of waves on a sloping beach. The wave,
retarded at its base, is carried forward above by its momentum,
and finally spreads far up on the strand; and if it could there
remain, the succeeding wave must necessarily find itself
superimposed upon the first. But no effects of inertia, no
kinetic effects, may be called to our aid in explaining the
formation of mountains. Some geologists have accordingly supposed
that in order to account for

[1] Marcel Bertrand, _Cong. Geol. Internat._, 1900, Guide Geol.,
xiii. a, p. 41.

[2] Lugeon, _loc. cit._, p. 773.

[3] De Lapparent, _Traite de Geol._, p. 1,773.

154

the recumbent folds and the peculiar phenomena of increasing
overlap, or _deferlement_, an obstacle, fixed and deep-seated, must
have arrested the roots or synclines of the folds, and held them
against translational motion, while a movement of the upper crust
drew out and carried forward the anticlines. Others have
contented themselves by recording the facts without advancing any
explanatory hypothesis beyond that embodied in the incontestable
statement that such phenomena must be referred to the effects of
tangential forces acting in the Earth's crust.

It would appear that the explanation of the phenomena of
recumbent folds and their _deferlement_ is to be obtained directly
from the temperature conditions prevailing throughout the
stressed pile of rocks; and here the subject of mountain
tectonics touches that with which we were elsewhere specially
concerned--the geological influence of accumulated radioactive
energy.

As already shown[1], a rise of temperature due to this source of
several hundred degrees might be added to such temperatures as
would arise from the mere blanketing of the Earth, and the
consequent upward movement of the geotherms. The time element is
here the most impo