ELEMENTS OF GEOLOGY. 
16 
Pig. 56. 
Curved strata of slate near St. Abb’s Head, Berwickshire. (Sir J. Hall.) 
which such strata, assuming them to have been originally 
horizontal, may have been forced into their present position. 
A set of la^^ers of clay were placed under a weight, and their 
opposite ends pressed towards each other with such force as 
to cause them to approach more nearly together. On the 
removal of the weight, the layers of clay were Jbund to be 
curved and folded, so as to bear a miniature resemblance to 
the strata in the cliffs. We must, however, bear in mind 
that in the natural section or sea-cliff we only see the fold¬ 
ings imperfectly, one part being invisible beneath the sea, 
and the other, or upper portion, being supposed to have 
been carried away by denudation^ or that action of w^ater 
which will be explained in the next chapter. The dark 
lines in the accompanying plan (Fig. 57) represent what is 
Fig. 5T. 
actually seen of the strata in the line of cliff alluded to; the 
fainter lines, that portion which is concealed beneath the sea- 
level, as also that which is supposed to have once existed 
above the present surface. 
