DEFORMATION OF ROCKS ; 207 
than the preceding. This may go beyond the limit of elasticity 
and produce minor plications. 
But the majority of strata which have been closely folded 
when bent were deeply buried beneath other strata. If the 
superincumbent weight was greater than the strength of the rock 
all parts of it were under compression, increasing, it is true, 
from top to bottom in an anticline, and if the mass is not too thick 
from bottom to top inasyncline. In this case there was no 
MV 
FIG. 3. | 
neutral plane. The rearrangements which took place were there- 
fore those of varying compression,—flowage away from the places 
of greatest compression and flowage toward the places of least 
compression. The crenulations in an anticline may mean that 
the part of the fold seen was in the compressed area, the 
stretched and fractured part being removed by erosion. Where 
both the anticlines and synclines show plications throughout, it 
follows that the superincumbent strata were so thick that no zone 
of stretching could be formed, the weight being beyond the 
supporting strength of the rocks, and the movements being 
those of a heterogeneous plastic body. 
Just as there is rearrangement of the particles within a bed, 
so there is readjustment of the beds over one another. This 
may be illustrated by a bunch of paper. (Figs. 2 and 3.) If straight 
lines be drawn at the edges of a bunch of horizontal sheets, 
and then the whole be bent into folds, it will be found that the 
straight lines become curved. In other words, the sheets were 
moved over one another. An examination of the curved lines 
