OROGENY AND EARTH’S ROTATION 
75 
circumference. On the globe these folds correspond closely in 
location to the positions of the continents. The fact that only 
three plaits should develop in numerous instances and that they 
should be unequally separated appears both in experiment and in 
Figure 4. Normal Continental Plait ^ 
nature to be more than mere fortuitous circumstance. It calls 
for special inquiry. It seems capable of reduction to a mathe¬ 
matical basis. 
Singularly enough anticlinoria are among the tectonic structures 
easiest of formation in recent experiments. Structures thus pro¬ 
duced in miniature simulate in all essential particulars those fa¬ 
miliar and often complex flexures which distinguish the great 
mountain tracts of the globe. Representative diagrams of several 
of them are represented in the accompanying cut (figure 5), which 
are pen-tracings of photographs. None of them are especially 
selected as particularly good examples; but they are normal, re- 
Figure 5. Development of the Cordilleran Anticlinorium 
curring figures. Reproduced time and again substantially as fig¬ 
ured the forms seem to be a necessary consequence of tempered 
tangential stress. This appears to find direct analogy in the cor¬ 
dilleran belts of the earth wherein corrugation takes place in the 
straticulate crust as a relief from tremendous telluric strain. 
A striking feature of the experimental production is the relative 
