PHYSIOGRAPHIC PROBLEMS OF TODAY 547 



Physiographers were given a new point of view when Darwin explained 

 the part played by the humble earthworms in modifying the earth's 

 surface. As it seems, still other advances in our knowledge of the 

 changes in progress in the vast laboratory in which we live may 

 be gained by studying the ways in which organisms far lower in the 

 scale than the earthworm are supplying material for the building of 

 mountains or assisting in the leveling of plains. 



In brief, a review of the inter-relations of physiography and hfe, 

 shows that from the lofty snow-fields reddened by Proioccocus, to the 

 bottom of the ocean, the surface of the lithosphere is nearly everywhere 

 enveloped in a film teeming with life. In part the vital forces at work 

 are reconcentrating material and adding to the solid framework of 

 the globe, and in part, but less obviously, aiding in rock decay and 

 disintegration. Throughout this vast complex cycle of changes new 

 physiographic features are appearing, others disappearing, and one 

 and all, to a greater or less degree, are undergoing modifications. 

 The wide extent of the changes in progress, and their known impor- 

 tance in certain instances, are justification for the belief that the 

 physiographer as well as the ecologist will find many problems of 

 fundamental importance to his science in the inter-relations of life 

 and physiographic conditions. 



PHYSIOGRAPHY AND MAN. 



Go forth, subdue and replenish the earth, is the language of 

 Scripture. The observed results show that, while man strives to 

 bend nature to his will, he himself is a plastic organism that is molded 

 by the many and complex external forces with which it comes in con- 

 tact. Here again two groups of themes present themselves to the 

 physiographer : one, embracing the influences of environment on man ; 

 and the other, the changes in the features of the earth's surface, 

 brought about by human agencies. In the first the physiographer 

 can aid the anthropologist, the historian, the sociahst, etc.; and in 

 the second, which is more definitely a part of his own specialty, he 

 searches for suggestive facts throughout the entire domain of human 

 activities. It is in these two directions that the student of the earth's 

 surface finds the most difficult and the most instructive of the prob- 

 lems in which he takes delight, and the richest rewards for his efi'orts. 



