E. B. Bailey — Iceland, a Stepping-Stone. 475 



Pacific ranges for information regarding the essential features of 

 arcuate mountain chains. The account he gives of them can hest be 

 realized by reproducing certain of his statements. 



"Three arcuate and concentric elements occur in the Asiatic 

 island festoons, namely, the foredeeps, the folded chains (cordilleras), 

 and the volcanic lines" (p. 504). 



In the Bonin Islands of the Pacific, concentric zones are recognized 

 as follows : — 



1. Poredeep. 



2. Tertiary belt, often folded. 



3a. Polded cordilleras, the innermost sometimes backfolded. 



3b. The volcanic arc " always in the cordillera, and more precisely 

 in the zone of for ef old my, never in that of backfolding, and never in 

 the foredeep. 



" The same structure is also present in the Northern Antilles, but 

 in these islands no cordilleras occur within the volcanic zone. In 

 general, the cordilleras are the first to show a tendency to disappear, 

 as may be seen in the Bonin islands, while the volcanos hold their 

 ground with great tenacity as in the Aleutian islands " (p. 516). 



" As a result of these comparisons we see that the North Antilles 

 (probably also the South Antilles), the Alaskides and all the island 

 festoons as far as the Philippines, the Oceanides also, and in Asia 

 the oppositely-curved Burman arc, present a similar structure, and 

 this structure, although less sharply defined, is also perceptible in 

 the southern marginal arcs situated in great part on the mainland. 



" The constant occurrence of the arc of active volcanos within 

 the zone of forefolding is a remarkable fact " (p. 524). 



It is not only in his descriptions of mountain chains that Suess 

 seems to contradict his old theory. "We have already referred to his 

 observations regarding certain arcuate fractures developed during the 

 partial subsidence of an asphalt pavement under conditions wherein 

 tangential pressure played no part whatsoever. As stated above, he 

 compares these arcuate fractures with those of Iceland, but he is 

 obviously more interested in their reproduction of the phenomena of 

 linhing and syntaxis, so characteristic of the mountain systems 

 (p. 503) ; moreover, he returns to their consideration when he 

 discusses the origin of foredeeps (p. 505). 



And yet his views in regard to the cause of the arcuate form of 

 the various elements of mountain ranges do not seem to have altered. 

 The arcuate mountain fronts he compares with certain moraines 

 described from Greenland, where inland ice, forcing its way between 

 nunataks, sometimes carries ground moraine up from the bottom, and 

 spreads it in arcs over ice in front, acting the part of foreland 

 (p. 528); and the foredeeps, he says, "are subsidences of the 

 foreland beneath the folded mountains" (p. 295). 



The difficulty of this theory is that it gives scant recognition to the 

 volcanic arc, the Cinderella of the piece. Other workers, less 

 acquainted with the Alps, have held that the line of volcanoes and 

 its frequent underground equivalent in the denudation series, the 

 line of batholiths, must be afforded a very prominent position in any 

 interpretation of mountain structure. The references that might be 



