MEDITERRAKEANS COMPARED WITH GEOSYNCLINES 197 



this very wide and long-enduring polygeosyncline is so because of its 

 developmental relation with the vastness of the Pacific, the greatest of 

 oceans. 



' ME80GE0SYNCLINE8, OR MEDITERRANEANS 



The mediterraneans are the areally smaller and decidedly elongate, but 

 most mobile oceans, and are more completely bounded by continents than 

 are the true oceans. They are characterized by abyssal waters, by ex- 

 cessive mobility, and by very intricate histories, combining eventually 

 several geanticlines and geosynclines. The Eoman Mediterranean is the 

 best known example, and, to distinguish this type from the other geosyn- 

 clines, they may be known as meso geosynclines (with reference to their 

 position between continents) or simply as mediterraneans. 



In Europe the theory of geosynclines centers in the structure of Tethys 

 and is set forth in the great work of Haug.*^ He defines them as follows : 



"The geosynclines, essentially mobile regions of the earth's crust, are always 

 situated between two continental masses or relatively stable regions. They 

 constitute, before their filling with sediments, marine depressions of quite a 

 considerable depth" (page 632). "It is evident that the folded mountain 

 chains have in general become emergent geanticlines, and divide the primitive 

 geosyncline into secondary ones. After the folding phase the whole is again 

 depressed, the geanticlines are again covered by the sea, and the same phe- 

 nomena are reproduced in the same order up to the emergent condition'' (page 

 708). 



Again : 



"Most often the strata of the geosynclines belong to the bathyal type. . . . 

 American writers have always taken as a point of departure for their theories 

 on mountain-making the fundamental idea that mountains are formed on 

 [inside of] the border of oceans, and that the continents increase by the addi- 

 tion of other chains, more and more recent. [The last part of this sentence 

 is not an American idea.] Under this hj-pothesis, geosynclines take birth at 

 the limit between continents and oceans, the sediments which accumulate there 

 are exclusively littoral, and the zone of sinking, with the greatest thickness 

 of strata, is separated from the ocean by a simple swelling." *^ 



From these quotations we see that Haug's theory of geosynclines is 

 far from the American conception of the evolution of the continent of 

 ^orth America as described in this address. In the first place, the conti- 

 nent was much larger in Proterozoic time than it is now, and paren- 

 thetically it may be added that the writer holds most of the continents 



*2 E. Haug : Les geosynclinaux et les aires continentales. Contribution h Tetude des 

 transgressions et des regressions marines. Bull. Soc. Geol. de France, 3d ser., vol. 28, 

 1900, pp. 617-711. 



«E. Haug: Traite de geologic, 1907, pp. 160, 166. 



