OF THE SOUTH DEVON COAST. 25 
as perhaps will have been inferred from some of my preceding remarks, 
the phenomena of the district described in this paper are eminently 
those indicative of a mountain chain*. They record more than one 
chapter in the history of mountain-making. I can hardly under- 
stand the production of those great parallel flexures which affect 
all south-western England, and especially this district—flexures 
whose undulations become broader and flatter as we trace them 
northwards, without assuming the existence to the south of them of 
a great axial mass of much harder rock, to the pressure of which 
these sharper crumplings are due. On comparing a section of 
South Devon with a series of sections across the Alps we cannot 
fail to be struck with the resemblance between them, except that in 
the former we do not find the crystalline nucleus rising up as the 
central mass of the chain, often overtopping and apparently over- 
lying the later deposits. But when we look to the south, beyond 
the South-Devon and South-Cornish schists, we find at the Hddy- 
stone—we find probably in the shallower parts of the neighbouring 
sea—we certainly find yet further south in the Channel Islands and 
on the adjoining coast of France—large masses, projecting from the 
ocean, of much more coarsely crystalline rock. Is it possible that 
these may be the foundation-stones of a great mountain region, of 
whose outer zone South Devon and South Cornwall are the last 
remnants—the relics of a long-vanished highland region of Archean 
rock? If so, the mountain-making—at any rate that with which 
we are now concerned—occurred after the Carboniferous, and prior to 
the Triassic epoch,—was, in short, one of the closing incidents of the 
Paleozoic volume of geological history. Yet the Channel sea now 
occupies the place where this range was upraised, and of its ruins 
some fragments only remain in situ. These remarks may seem to 
belong rather to the poetry than to the prose of science; but I 
think that any one who will spend a few years in studying the 
structure of rocks and of mountain-masses will see that the idea 
conveyed by them is something more than a baseless flight of imagi- 
nation #. 
of compression, intrusive igneous rocks abound. ‘This is, of course, what was 
to be expected. 
* See also in illustration of this the sections in Dr. Holl’s paper, especially 
fig. 1, p. 409, and fig. 5, p. 438. 
t A thorough study of the rocks composing the Triassic conglomerates of 
Devonshire would give, I am sure, most interesting results. Whoever under- 
takes it must be a resident in Devonshire ; for the field-work will take no little 
time ; he must bea skilled petrologist, or his results will be worse than useless ; 
and he must have a special knowledge of the rock masses of Devonshire and 
Cornwall. Among the many excellent geologists and enthusiastic students of 
the West of England is there no one to undertake this task, and endeavour to 
replace the covering which has been stripped from the granitic bosses, and 
rebuild the hills which the sea has destroyed ? 
{ There is another more general conclusion to which I may call attention, 
namely, the importance of pressure as modifying rock structure. Rocks sub- 
jected to much pressure, folded, and squeezed out of shape, appear to undergo 
more micro-mineralogical change than similar rocks when not so maltreated. 
Perhaps it is hardly too much to say that the difference between a satiny 
slate or phyllite and an ordinary shale is due even more to the action of 
i ei 
