GEOLOGY 137 



existing continents. Thus he shows the kinship, so to speak, 

 in geological constitution, between India and Arabia on the 

 one hand and Africa on the other, as well as the fact that 

 India and Arabia are foreign to the main body of Asia in 

 geological history and constitution. From these and other 

 fragments of similar character and parallel historical devel- 

 opment, he builds the ancient Gondwana continent that in- 

 cluded Africa, India, Arabia, Madagascar, the Indian Ocean, 

 Australia, the South Atlantic, and part of Brazil. Through 

 breaking and collapse of parts, this has been changed to the 

 existing conditons of land and sea. 



In like manner, he shows the great similarity in existing 

 character, in historical development, and in relation to other 

 areas of northeastern North America and northwestern 

 Europe. Here again, by a masterly marshaling of evidence 

 of great diversity of character and origin, he rebuilds the 

 ancient continent of Atlantis and shows that in all probability 

 it continued to bridge what is now the North Atlantic until 

 a very short time ago geologically — almost, or possibly quite, 

 up to the time of the advent of man on the earth. He does 

 not stop with these broad general results, but extends his 

 studies to the detailed development of the continental sur- 

 faces themselves through mountain building and faulting. 



It is unnecessary, however, to go further in reviewing 

 his results. Suffice it to say that his is the first attempt to 

 deal with these features in a world encompassing way. 



The principles so far defined, in so far as they concerned 

 process at all, implied, if they did not explicitly postulate, 

 the constructive action of that process. The formation of 

 the rocks of the earth's crust, both igneous and sedimentary, 

 is effected through the action of constructive processes. The 

 construction of mountain ranges, of high plateaus, or even of 

 ocean basins, is brought about through the operation of con- 

 structive processes, either positive or negative. The build- 

 ing up of the sea bottom, the filling of lakes, the progressive 



