PROGRESSION OF GLACIERS. 
These papers seem to have been overlooked by con- 
temporary investigators, and I may be permitted 
to translate here a passage from one of them, since 
it sums up tlie results of tlie inequality of motion 
throughout tlie glacier and its influence on the 
primitive stratification of the mass in as few words 
and as correctly as I could give them to-day, 
twenty years later : — u Combining these views, 
it appears that the glacier may be represented as 
composed of concentric shells which arise from 
the parallel strata of the upper region by the fol- 
lowing process. The primitively regular strata 
advance into gradually narrower and deeper val- 
leys, in consequence of which the margins are 
raised, while the middle is bent not only down- 
ward, but, from its more rapid motion, forward 
also,- so that they assume a trough-like form in 
the interior of the mass. Lower down, the gla- 
cier is worn by the surrounding air, and assumes 
the peculiar form characteristic of its lower 
course.” The last clause alludes to another se- 
ries of facts, which we shall examine in a future 
article, when we shall see that the heat of the 
walls in the lower part of its course melts the 
sides of the glacier, so that, instead of following 
the trough-like shape of the valley, it becomes 
convex, arching upward in the centre and sink- 
ing at the margins. 
I have dwelt thus long, and perhaps my read- 
