208 SIMGIDIGES, JADE SIN GIDBIN IES 
shows that on opposite sides of an anticline or syncline the move- 
ment for any given stratum is in opposite directions. Therefore 
at the anticlines and synclines the forces are directly opposed 
and hence the stretching or plications at these places, as already 
explained. But on the limbs of the folds the forces are in 
the same direction for each lamina, but in opposite directions for 
laminze upon opposite sides of any layer, thus constituting a 
couple. Each stratum moves up as compared with the one next 
below it, and each stratum moves down as compared with the one 
next above it. In the case of much inclined and overturned 
folds this statement needs modification. 
The axial lines also show that on the crests of the anticlines and 
inthetroughs of thesynclines there was comparatively little move- 
ment, whileatthe middle of the limbs of the folds movements were 
ata maximum. From this experiment and from Figs. 4 and 5 we 
would expect that in folded rock strata the effects of readjustment 
would be least at the crests of the anticlines and troughs of the 
synclines and most at the middle of the limbs, and such are the 
facts. Ina subsequent article it will be seen that clastic rocks 
become crystalline in proportion to the degree of shearing and 
the intensity of the pressure. The former is at a maximum on 
the limbs of folds and at a minimum on the crests and troughs. 
Further, secondary structures may develop on the limbs nearly 
parallel to the beds, while upon the anticlines and synclines the 
secondary structures form across the beds. It follows that on 
the anticlines and synclines, where there is most crenulation 
and puckering of the laminez, the original structures are less 
altered, and the clastic characters in sediments, such as sand- 
stones and conglomerates, are likely to be preserved. Upon the 
other hand, upon the limbs of the folds the obliteration of frag- 
mental characters may be complete. We therefore have the 
paradox that where there is most crenulation there is least meta- 
morphism; where least crenulation, most metamorphism. This 
of course applies only to the different positions of the rock in 
a fold, not to a gently folded district as compared with a more 
closely folded area. 
