STRATIGKAFHIC CLASSll'ICATlON DIASTROPHIC CRITERIA 397 



iiiit himself positively, still seems to question the possibility of a Gond- 

 wana land, and of transatlantic lands, one connecting South America and 

 Africa and another North America with northern Europe. That such 

 dependencies and intercontinental connections did exist at various times 

 in geologic history — their exact location is another matter — seems incon- 

 trovertibly established by the geographic distribution of certain fossil 

 faunas and floras. These east-west connecting lands were emerged at 

 times when the horizontal movements of the shell in a north-south direc- 

 tion dominated those acting in the opposite direction. The latter won in 

 the long run, the connecting lands being finally dragged down in the 

 aggregate growth of the oceanic geosynclines to depths from which it 

 seems unlikely that they can ever again emerge. 



I must take issue with Willis also when he says (Science, February 18, 

 1910, page 243) "in their genesis ocean basins and geosynclines may have 

 been similar ; but in their dimensions, histories and structural relations 

 they are radically different;'^ and again to his succeeding statement (op. 

 cit., page 244) that the "distinction between geosynclines and ocean basins 

 is fundamental" because the former "occupy positions among the positiva 

 continental elements" the latter "separate and surround continents . . . 

 and no ocean basin has been compressed, crumpled and raised, after tlie 

 manner of the Appalachians or Alps." As I see it, the differences are 

 merely relative — matters chiefly of magnitude — and therefore neither 

 radical nor fundamental. Indeed, in conceding similarity in genesis, 

 Willis himself tacitly admits this. Had he compared a whole continent 

 and not merely one of its compound synclines with the oceanic basins, he 

 might perhaps justly have called one the antithesis of the other, the one 

 being characterized by dominance of positive tendencies, the other by nega- 

 tive. Both, however, include areas that are synclinal in structure, being 

 relatively depressed, with respect to adjacent areas, and each of the oceanic 

 basins comprises several pronounced geosynclines and weaker geanticlines 

 just as the continents are made up of several strong geanticlines and rela- 

 tively subordinate geosynclines. That compression and resulting folding 

 and crumpling was developed to a less degree in the irregular floor of the 

 oceans than on the continents is probably true, but to say that no ocean 

 basin was compressed "after the manner of the Appalachians" seems un- 

 reasonable. That there is no sharp boundary of fundamental struc- 

 tural significance between those parts of the earth-crust that lie beneath 

 the sea and those which form the land is shown, as T believe, conclusively 

 by the fact that compressed and folded areas, both new and old, still high 

 or reduced, strike from the land into the sea. And the contours of the 



