878 HISTORICAL GEOLOGY. 



a continent, causing displacements of the rock formations along lines 

 measuring hundreds of miles in extent, must have been attended by a 

 succession of earthquakes of unwonted violence, which would have caused 

 destruction by the vibrations in the rocks beneath, and also indirectly through 

 the deluging waves sent careering over the land from any seas in the range 

 of the vibrations. Whenever the shakings of the continent extended 

 beneath the ocean, these deluges from earthquakes of Laramide origin would 

 have been destructive over all the coasts of a hemisphere. As land was 

 mostly low at the time, the earthquake waves may have made their marches 

 inland for hundreds of miles, and have left alive only the smaller animal 

 species and the vegetation. 



This sweeping from the world of so large a part of its life, and especially 

 that of Mesozoic characteristics, was a much-needed preparation for the era 

 of the " Reign of Mammals." It was an opportunity for the " survival of 

 the fittest " on a grand scale ; that is, the survival of those species that could 

 withstand the special causes of destruction, and of the many that were out 

 of harm's way. The exterminations were the removals of hindrances to 

 progress. The survival of the fittest and of the lucky ones, while not directly 

 species-making, was the origin of new associations in continental and oceanic 

 life ; that is, of new faunas and new floras over the world, in which, under 

 the modified geographical and physical conditions, the elements existed for 

 further change and progress. 



