ZOOGEOGRAPHY. 147 



practically unchanged since its geologic infancy. There has been an inclination 

 to look askance at those who do not beUeve in the permanence of land forms 

 almost as they exist today. Suess, however, says that "the crust of the Earth 

 is traversed not only by isolated faults, * * * but Ijy whole systems of fractures, 

 that extensive areas have thus been broken up, and have foundered into the 

 interior of tlie planet" (Suess, 1, p. 7). Again, he remarks that the enthusiasm 

 which we have expended in contemplating the part that the little polyp has played 

 in building up the coral reef, or that the rain-drop has performed in hollowing 

 out the stone, have brought the commonplaceness of everyday life into our 

 conception of the phenomena of the past. In his opinion the convulsions which 

 have affected parts of the crust of the earth have been greater, and of greater 

 frequency, than was formerly supposed. "The earthquakes of the present day 

 are certainly but faint reminiscences of those telluric movements to which the 

 structure of almost every mountain range bears witness." Enormous changes 

 of level have taken place upon the siu'face of the earth in such recent times, 

 geologically speaking, that one can fairly consider these changes to be hardly 

 less than others whose existence can not be proved geologically. These sup- 

 posedly have been brought about by the folding of the surface of the earth, or 

 by depression of those areas of the lithosphere which, once dry land, now lie 

 deep below the sea. The elevated valley of California, and the upper valley of 

 the Po in Europe are excellent examples of regions where enormous changes of 

 le\el of land in relation to sea have taken place since late Pliocene and probably 

 even since early Pleistocene times. The northeastern coast of North America 

 is fast sinking at the present. Where lines of recent volcanic activity, as in the 

 East Indian and West Indian Island areas, occur, one may fairly assume that 

 fundamental changes of level have taken place, or may take place in any short 

 space of time. These regions lie in geosynclines, areas where changes of level 

 are most likely to occur, for there folding and faulting are at a maximum. Prof. 

 J. B. Woodworth has told me that he considers it as not at all an extravagant 

 statement to say that, so far as the geologic evidence is concerned, the Brazilian 

 highland area may be projected indefinitely into the Atlantic basin; and the 

 same thing is true of the probable projection of the Chilean region into the 

 Pacific. He has recently studied both these regions in great detail. The geologic 

 evidence as to the great age of the Atlantic Ocean is purely negative. So late 

 as the Upper Trias there were, except for a small area in the Atlas Mountain 

 region, no marine sediments laid down by the existing shores of the Atlantic. 



We know that the facility with which animals of various orders are trans- 



