204 SIN QIQIGES, JHOVER SIMYIOV BIN TES 
the strong formations bent into synclines because of the thrust 
ransmitted along their limbs furnished in part by the weight 
carried by the adjacent anticlines, will give increased pressure to 
the softer beds below and add to the ordinary thrust which is 
already forcing the material to follow the arches of the adjacent 
anticlines. However, if the superincumbent strata be but suffi- 
cient, the strongest and most brittle rock beds, such as quartzite 
and jaspilite, may be crumpled or bent upon themselves within 
their own radius without macroscopic sign of crevice or fracture. 
In extreme cases the microscope is unable to detect any evidence 
of crevices or cracks, but it shows in a most remarkable manner 
that the mineral particles have been greatly flattened. 
The thinner and softer the beds the less potent are they to 
control the movement of any considerable amount of material. 
Therefore, under given conditions, the thinner and softer the beds 
the shorter and the steeper are the folds, and more nearly does 
their material approach in its movement to the flowage of tallow. 
In soft homogeneous shales the approximation is closest. There- 
fore, in a series or group of beds of different lithological char- 
acters, the thick, strong beds are less closely folded than the thin, 
weak beds. The softer layers are greatly thickened here and 
greatly thinned there, as demanded by the stronger layers. 
The folding of the first may be comparatively simple, and the 
second may be closely plicated. These principles are finely 
illustrated in the Hiwassee section of the Ocoee series of the 
southern Appalachians. 
In any great anticlinorium, even if the strongest rock be at 
the bottom—for instance, a massif of granite—it yields to the 
force of thrust under the law of normal plastic flow, moving toward 
the places of least compression, and ever presses against and 
helps to raise and support the overlying arch of sedimentary 
and other rock. If a massif were absolutely homogeneous with- 
out reference to its strength, its movements would be analogous 
to that of wax. Consequent upon such movement, as explained 
in a subsequent paper, it is believed that uniform cleavage is often 
produced. But no massif is homogeneous. It is composed of 
