DEFORMATION OF ROCKS B21 
(6) Composed fan fold. The primary fold is composed of 
a set of secondary folds which at the crown are upright, and in 
passing in either direction transverse to the primary axial plane 
the secondary folds are first inclined and then overturned. The 
secondary folds may be ordinary, isoclinical, or fan-shaped. The 
Fic. 8.—Ideal composed fan fold. 
two sets of secondary axial planes on opposite sides of the 
crest of the primary fold diverge upward and converge down- 
ward (Figs. 8 and 9). Often in extreme cases of compression at 
/ 
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La & (Bros pr ff 
IANS WN LAT > hr IA 
WT ANNES WN MAG OGG Uf LELGABE 
REMAN Wp WI IGEGIYGEIETD 
RATATAT MMS LE 
SN | KC 
SD) SB N24 4 4 
gy SS SSW 227/44 
Fic. 9.—Generalized fan-fold of the central massif of the Alps. After Heim. 
the crest of the primary anticline the secondary folds are fan- 
shaped, and passing in either direction these grade into isoclinal 
and then into ordinary folds. Such are many of the composite 
folds of the Alps. 
The inclined normal anticlinorium.—The primary fold of the 
inclined normal anticlinorium 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 crest of the 
