MEDITERRAXEAXS COMPARED WITH GEOSYNCLINES 199 



Hang;, seeing clearly that iQesogeos}Ticlines lie between continents, and 

 that the marine loading areas of today are situated npon the outer edges 

 of the continents — the continental shelves — postulates these same places 

 for the geosynclines of Mesozoic time. However, continental shelves 

 have not the trough structure of geos}Ticlines, and to get such troughs 

 here during Mesozoic time, Haug postulates and maps continents, though 

 with a great deal of doubt, over the entire areas of the present oceans I 

 Accordingly, his theor}^ calls for mesogeos}Ticlines ; but his making land 

 of nearly all the oceans leads us to ask, What has become of all the marine 

 water of Mesozoic time? Of course, he can give no answer. We can 

 partiall}^ help him out of his difficulty by postulating ( 1 ) for the greatest 

 geosynclines an i/i^er-continental position — that is, the mesogeosynclines 

 and oceans — and (2) an mtra-continental position for the polygeos3'n- 

 clines and monogeosynclines. At present the earth is without active geo- 

 synclines in the sense of those of Mesozoic and Paleozoic times. The 

 continental shelves are not geosynclines, since they have no outer border- 

 lands. 



At the present time there appear to be no monogeos}Ticlines in forma- 

 tion, unless it be (1) the Baltic Sea and Gulf of Bothnia making their 

 way into the White Sea, or (2) the Persian Gulf heading through Meso- 

 potamia into the Mediterranean. The Eed Sea is a rift sea, with depths 

 down, to 6,000 feet, and the Gulf of California, with a major depth of 

 over 10,000 feet, appears to be another. 



Of polygeosynclines there also appear to be none now in formation. 

 In regard to mesogeosynclines, the Mediterranean is clearly one and the 

 Caribbean another. 



The island arcs off eastern Asia inclose the Sea of Okhotsk (depth to 

 12,000 feet), Japan Sea (10,500), Eastern Sea, and China Sea (16,100). 

 The Yellow Sea appears to be nearly tilled with sediments, since the 

 greater part has depths less than 400 feet, but a small outer part goes 

 down to over 7,700 feet. These recording basins can not be grouped into 

 any of the mentioned types of geosynclines, since some of them have 

 oceanic depths, but all are actually a part of the Asiatic continent. They 

 are marginal geosynclines or parageosynclines (geosynclines beside a 

 continent) and contrast with mesogeosynclines that lie between conti- 

 nents. 



OCEANS 



The largest sinking fields are, of course, the oceans, with their down- 

 fractured or downwarped parts of continents, their geanticlines, and their 

 mountains of extrusion that are either single, clustered, or arranged in 



XIV — Bull. Geol. Soc. Am., Vol. 34, .1922 



