EURASIA 191 



radius of nearly 1,300 miles, and its curvature is remarkably perfect for 

 a feature of this kind. The island arcs off the east coast are almost as 

 nearly circular in their curvature. But westward from Burma the first 

 range, omitting the Himalaya arc, shows many irregularities that break 

 up the simplicity of its curves. 



From Asia Minor to the Philippines the peripheral belt of Tertiary 

 folds is not a single folded line, but consists of two or three lines, some- 

 times more, lying one behind the other. From the Philippines to Alaska, 

 however, the Tertiary belt is a single fold-line, so far as known. The 

 reason for this difference is not known with certainty. As Suess says, 

 we do not know the character of the platforms upon which lie the seas 

 behind the island arcs ; there may be other weaker, lower fold-lines behind 

 the arcs, or the platforms may be composed of ancient, crystalline rocks 

 which moved as ^^plates^' without parallel foldings. In Europe and 

 western Asia the resistance of the Indo-African plateau may have con- 

 tributed largely to the making of parellel fold-lines, but this would 

 hardly apply to the Malay arc between Burma and the Philippines. ISTev- 

 ertheless, the absence of any obstruction along the east coast would seem 

 to have favored simpler results there. 



The peripheral mountain arcs form a continuous frontal fold for the 

 whole southern border of the continent, and are apparently all of one 

 age. Regarded as a product of crustal deformation, this fold appears to 

 he a unit in both extent and time, and it is therefore a unit in dynamic 

 process also. A mighty creeping movement of the earth's crust from 

 tlie north toward every part of the vast periphery appears to have taken 

 place, and the area of earth-crust involved appears to have been as great 

 or greater than the entire expanse of Asia. This idea is very different 

 from the conception of Suess, who pictures the ancient vertex in Siberia 

 as the center from which all the movements took place, the vertex re- 

 maining unmoved, while the crust around it moved away in slightly 

 divergent southerly directions. 



THE HIMALAYA RE-ENTRANT AND THE MALAY EARTH-LOBE 



The most pronounced departure, however, from a fairly even front for 

 Asia is found in the contrasted forms of the Himala^^a re-entrant and 

 the Malay earth-lobe. If we contemplate the plan of the trend-lines, as 

 shown in figure 2 for these two features, it seems apparent that it was 

 the obstructing action of the Indian peninsula which produced the great 

 Himalaya re-entrant. It was the tremendous resistance offered by this 

 fragment of the ancient Gondwana-land which held back the advancing 

 folds to the line of the Himalaya. The effect seen in horizontal plan is 



