ANTICLINAL ANI) SYNCLINAL LINES. 
85 
Figs. 66 and 67 may occasionally be encountered in follow¬ 
ing the same line of flexure at points a few miles distant 
from each other. A miner unacquainted with the rule, who 
had first explored the valley Fig. 66, may have sunk a vert¬ 
ical shaft below the coal-seam A, until he reached the inferior 
bed,’B. He might then pass to the valley. Fig. 67, and dis¬ 
covering there also the outcrop of two coal-seams, might be¬ 
gin his workings in the uppermost in the expectation of com¬ 
ing down to the other bed. A, which would be observed 
cropping out lower down the valley. But a glance at the 
section will demonstrate the futility of such hopes.* * 
Synclinal Strata forming Ridges.— Although in many cases 
an anticlinal axis forms a ridge, and a synclinal axis a valley, 
as in A B, Fig. 63, p. 82, yet this can by no means be laid 
down as a general rule, as the beds very often slope inward 
Fig. 69. 
Synclinal. Anticlinal. Synclinal. 
^ • 
Grits and shales. Mountain limestone. Grits and shales. 
Section of carboniferous rocks of Lancashire. (E. Hull.t) 
from either side of a mountain, as. at a, Fig. 69, while in 
the intervening valley, c, they slope upward, forming an arch. 
It would be natural to expect the fracture of solid rocks 
to take place chiefly where the bending of the strata has 
been sharpest, and such rending may produce ravines giving 
access to running water and exposing the surface to atmos¬ 
pheric waste. The entire absence, however, of such cracks 
at points where the strain must have been greatest, as at a. 
Fig. 63, is often very remarkable, and not always easy of ex¬ 
planation. We must imagine that many strata of limestone, 
chert, and other rocks which are now brittle, were pliant 
when bent into their present position. They may have owed 
their flexibility in part to the fluid matter which they con¬ 
tained in their minute pores, as before described (p. 62), and 
in part to the permeation of sea-water while they were yet 
submerged. 
* I am indebted to the kindness of T. Sopwith, Esq., for three models which 
I have copied in the above diagrams; but the beginner may find it by no 
means easy to understand such copies, although, if he were to examine and 
handle the originals, turning them about in dilferent ways, he would at once 
comprehend their meaning, as well as the import of others far more compli¬ 
cated, which the same engineer has constructed to illustrate faults. 
t Edward Hull, Quart. Geol. Joum., vol. xxiv., p. 324. 1868. 
