678 W. M. DAVIS 



of our own science, but of the branches of our own and of other 

 sciences, is truly a great step toward the solution of the wonderful 

 riddle of the world. 



The real foundation of the broad consideration of earth science 

 rests on the continuity of ordinary processes through the long periods 

 of recorded earth-history. Nothing has so profoundly modified the 

 appreciation of other subjects as well as of our own, as the teaching 

 of geology concerning the conception of time and the long procession 

 of orderly events that has marched through it. Such a conquest of 

 the understanding is enough to make us proud indeed; yet when we 

 realize how short a share of time has been allotted to us, how sincere 

 should be our humility ! Today we may be lords of creation, powerful 

 through cephalization ; yet in face of the repeated extinction of domi- 

 nant races in geological history, how can we think otherwise than 

 that we are clad only in a little brief authority; how can we seriously 

 believe that we represent the highest stage, the acme of organic 

 development, comforting and flattering as this deductive opinion 

 may be! 



The conception of the continuity of processes, without extra-natural 

 interference, has been forced to fight its way against opposition ; now 

 it has gained at least a very general verbal acceptance among us, and 

 is quietly drifting into popular belief. To realize its full meaning 

 is an arduous task, not only because of the opposition of inherited 

 prejudices, but even more because of the inherent difficulty of the 

 problem. To think that processes such as those of today have done 

 all the work of the past is appalling; yet we are constrained to believe 

 it. Even as waves, beaten up in a stormy sea, subside after the winds 

 are calmed, so the mountain waves or wrinkles of the earth's crust, 

 growing as long as orogenic storms are at work, are in time calmed 

 to plains; and this not by unusual processes, but by the patient 

 weathering and washing of scraps and grains. While these slow 

 changes go on in the extinction of mountain systems, the races of 

 plants and animals that originally gained possession of the lofty 

 young mountains, that grew up with them so to speak, must either 

 adjust themselves to the changes in their surroundings, or migrate 

 to other homes, or vanish, all in due order through the flowing current 

 of time. 



