MECHANICS OF FORMATION OF ARCUATE MOUNTAINS 79 



6. Within the geologically recent peninsula which comprised 

 the present Malayan peninsula, Indo-China and Malaysia, the 

 arcs are developed in relatively much narrower and deeper festoons 

 than elsewhere, thus giving the impression of having been subjected 

 to strong lateral compression. 



7. Locally and upon the outermost series of arcs, particularly, 

 are superimposed arcs of smaller order of magnitude arranged 

 after the manner of a scalloped border (Sewestan, Timor, etc., 

 Fig. 2, a, b, c, d). 



8. The outer group of arcs is paralleled by near-lying arcs of 



Fig. 3. — The multiple arc of Sewestan, British 'India (after de Saint Martin 

 and Schrader). 



volcanoes generally upon the concave margin, and these vents are 

 characterized by unusually strong activity (see Figs. 2, 4, and 5). 



9. Upon the convex margin of the outer series of arcs particu- 

 larly lie "fore-deeps" (Fig. 5). 



10. The outer series of arcs is characterized by extraordinary 

 seismic activity (Fig. 6). 



1 1 . The outer arcs lying between the ancient Angara land-mass 

 and the Pacific Ocean are to a marked degree asymmetric, each 

 succeeding arc in the series springing from the side of its neighbor 

 (see Fig. 2). 



Structural peculiarities of the arcs. — Of all mountain arcs of 

 strongly marked Asiatic type, the Alps have been most carefully 



