318 HISTORY OF GEOLOGY AND PALAEONTOLOGY. 



The older view, that in the Northern Hemisphere, from the 

 Caspian Sea to the American shores of the Pacific, folding- 

 movements had been directed to the north, north-west, or 

 north-east, is shown to be erroneous for the southern Apen- 

 nines and other outrunners of the Alpine system, as well as 

 for the coastal chains in North America. A special chapter is 

 devoted to the work of Mojsisovics on the inthrown area of 

 the "Dolomites" in South Tyrol, with which the origin of the 

 Adriatic Sea is associated. 



Another chapter is devoted to the geological history of the 

 Mediterranean Sea, which he proves to be a remnant from a 

 much greater ocean. He calls this ancient ocean "Thetys," 

 and by an exhaustive discussion of the various Tertiary 

 deposits demonstrates the former extent, boundaries, and 

 phases of development of the original ocean of "Thetys." 

 It extended across the Atlantic Ocean to the southern coasts 

 of North America, and through Central Europe to the inner 

 recesses of Central Asia. The fragmentation of the neighbour- 

 ing continents, the recent inthrows of the y^Egean and Black 

 Seas, are described with admirable mastery of detail. 



The following chapters treat the Sahara table-land, with 

 its continuation towards Arabia and Palestine ; the broad 

 South African table-land, which formerly extended as 

 " Gondwana Land " across Madagascar to Southern India and 

 Australia and is bounded on all sides by a faulted coast ; and 

 lastly, the mountain-systems of India and Central Asia and 

 their tectonical relations to the Alps and European mountains. 

 Suess then proceeds to describe the leading features of America. 

 In South America there is a certain unity of structure. In 

 the east and in the middle the great Brazilian table-land is 

 composed of little disturbed Palaeozoic strata ; in the west the 

 folded mountain-chains are mostly composed of Jurassic rocks. 

 Still younger strata occur near the Pacific coast, and the 

 volcanoes and earthquakes of this area indicate the continuance 

 of crust-disturbances in the present day. 



Central America is interposed between North and South 

 America with a structure geologically independent of either, 

 and representing a part of the former land-girdle of the Thetys. 

 In North America, the Appalachians, the Mountains of the 

 West, and the intervening table-lands afford the author 

 frequent opportunity of discussing the American literature on 

 the origin of mountain-systems. 



