DEFORMATION OF ROCKS 328 
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 of the major fold converge upward 
and diverge downward. The secondary folds may be ordinary, 
isoclinal, or fan-shaped (Fig. 11). 
The inclined normal synchinorium.—The primary fold of the 
Fic. 11.—Ideal section of an inverted intermont trough. 
inclined normal synclinorium 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, which are inclined or overturned. The two sets 
of secondary axial planes on opposite sides of the trough of 
the major fold converge upward and diverge downward. The 
secondary folds may be ordinary, isoclinal or fan-shaped. 
The overturned normal synchinorium.—The primary fold of the 
overturned normal synclinorium has an inclined axial plane, and 
_the limbs at corresponding points have equal or unequal average 
dips in the same direction. The primary fold is composed of 
a set of secondary folds, which are overturned in the same direc- 
tion as the primary fold. The two sets of axial planes of the 
secondary folds on the opposite sides of the trough of the major 
fold converge upward and diverge downward. The secondary 
folds may be ordinary, isoclinal, or fan-shaped. 
ABNORMAL COMPOSITE FOLDS. 
The upright abnormal anticlinortum.—vVhe primary fold of the 
upright normal anticlinorium has a vertical, or nearly vertical, 
axial plane, and the limbs at corresponding points have nearly 
