
520 GEOTECTONIC (STRUCTURAL) GEOLOGY. [Boox IV. — 
fissile shales have been corrugated by subsiding heavy masses of 
more solid rock (Fig. 244). But it is, of course, among the more 
licated parts of mountain-chains that the structure receives its 
ex illustrations. Few travellers who have passed the upper end 
of the Lake of Lucerne can have failed to notice the remarkable 
cliffs of contorted rocks near Fluelen. But innumerable examples 
of equal or even superior grandeur may be observed among the 
more precipitous valleys of the Swiss Alps. No more impressive 










Fic. 245.—Pirce or ALPINE LIMESTONE, SHOWING FINE PUCKERING PRODUCED BY 
GREAT LATERAL COMPRESSION, 
mountains were upheaved. And yet, striking as are these colossal 
examples, involving as they do whole mountain masses in their 
folds, their effect upon the mind is even heightened when we dis- 
cover that such has been the strain to which solid limestones and 
other rocks have been subjected that even their minuter layers have 
been intensely puckered. Some of these minor crumplings are readily 
visible to the eye in hand-specimens (Figs. 18, 245). But in many 
foliated crumpled rocks the puckering descends to such extreme 
minuteness as to be discernible only with the microscope (Fig. 19). 

Fig. 246.—UnequaL Compression or Coan In CRUMPLING, PeMBROKESHIRE (B.). © 
It may often be observed that in strata which have been intensely 
crumpled, the same bed is reduced to the smallest thickness in the 
arms of the folds, but swells out at the bends as if squeezed laterally 
into these loops. ‘This appearance, so noticeable on a great scale in 
mountain structure, may be seen locally among low grounds, as in 
