3206 SINGIDIOES IFO: SI OLDIGIN ICS 
The overturned abnormal synchinortum.—The primary fold of 
the overturned abnormal 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 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 trough diverge upward and 
converge downward. 
OCCURRENCE AND ORIGIN OF COMPOSITE FOLDS. 
Higher orders of folds.— In all of the above cases the secondary 
folds of the primary anticlinoria and synclinoria may themselves 
be anticlinoria and syclinoria. The tertiary folds of the second- 
‘ary anticlinoria and synclinoria may also be anticlinoria and 
synclinoria, and so on to the zth order. The higher orders of 
the anticlinoria and synclinoria are microscopic. Each higher 
order of anticlinorium and synclinorium may be described with 
reference to the anticlinorium and synclinorium of the next 
lower order in a manner similar to the description of the primary 
anticlinorium and synclinorium with reference to a simple fold 
of the first order of magnitude. 
Even in regions of gentle folding, looked at in a large way, 
anticlinoria and synclinoria are the rule rather than the exception. 
In regions of moderately close folding the secondary anticlinoria 
and synclinoria, as a rule, are themselves anticlinoria and syn- 
clinoria. However, it is in such regions as the Alps, Canada, 
eastern United States, and Lake Superior that occur the complex 
anticlinoria and synclinoria composed of folds of different orders 
up to the wth order. 
The primary anticlinoria and synclinoria are usually upright 
or slightly inclined. The higher orders of anticlinoria and syn- 
clinoria are usually inclined or overturned. The very large syn- 
clinoria and anticlinoria on the flanks of the massifs of the Alps, 
in the Green Mountains of Massachusetts, the southern Appala- 
chians, and many other mountain ranges, many of them miles in 
length, are to be considered as secondary folds composing a 
