DEFORMATION OF ROCKS 325 
and the limbs at corresponding points have equal or unequal 
average dips in the same direction. The primary fold is com- 
posed of a set of secondary folds, which are overturned in the 
same direction as the primary fold. The two sets of secondary 
axial planes on opposite sides of the crest converge upward and 
diverge downward. The secondary folds may be ordinary, iso- 
clinal, or fan-shaped. 
Fic. 14. — Ideal section of an upright abnormal synclinorium. 
The upright abnormal synclinorium.— The primary fold of the 
upright abnormal synclinorium has a vertical, or nearly vertical, 
axial plane, and the limbs at corresponding points have nearly 
equal average dips in opposite directions. The primary fold is 
composed of a set of secondary folds, which at the trough are 
upright, and in passing in either direction transverse to the 
primary axial plane the secondary folds are first inclined and 
then overturned. The two sets of secondary axial planes on 
opposite sides of the trough diverge upward and converge down- 
ward. The secondary folds may be ordinary, isoclinal, or fan- 
shaped (Fig. 14). 
The inclined abnormal synclinorium.—The primary fold of the 
inclined abnormal syclinorium has an inclined axial plane, and 
the limbs at corresponding points have unequal average dips in 
opposite directions. The primary fold is composed of a set of 
secondary folds, all of which are inclined or overturned. The 
two sets of secondary axial planes on opposite sides of the trough 
diverge upward and converge downward. The secondary folds 
may be ordinary, isoclinal, or fan-shaped. 
