648 PHYSIOGRAPHY 



Can predictions be made as to what the results of a given combina- 

 tion of physical conditions on a given community will be, in spite 

 of that other and still more mobile, and as yet but little understood, 

 group of conditions embraced under the term psychology ? Many 

 profound questions, in the solution of which the physiographer 

 unites his efforts with those of the student of the humanities, present 

 themselves for study during the century that is yet young. 



Within the broader questions just suggested are many others that 

 are more concrete and definite, and of vital importance to mankind, 

 which can be conveniently grouped under the term economic physio- 

 graphy. The problems which here present themselves share their 

 chief interests with the engineer. They relate to plans for transport- 

 ation in all of its various forms, drainage, irrigation, water-supply, 

 sanitation, choice of municipal locations, control of river-floods, 

 selection of cities for homes, farms, vineyards, factories, etc. In every 

 branch of industry a critical knowledge of the physical conditions, 

 both favorable and adverse to the economic ends in view, and of 

 the limitations of the daily, seasonal, and secular changes they 

 experience, is of primary commercial importance. Although the 

 money- value of truth should be a secondary consideration to the 

 truth-seekers, a critical study of the influence of environment on 

 industry is as truly a matter of scientific research as any of the less 

 complex and less directly utilitarian branches of physiography. 



The reaction of human activities on physiographic features pre- 

 sents two great groups of problems. These embrace, on the one 

 hand, the far-reaching and frequently cumulative effects of man's 

 interference with the delicate adjustment reached in natural condi- 

 tions before his influence became manifest; and, on the other hand, 

 the effects of such changes on man's welfare. 



A change, amounting to but little less than a revolution in the 

 long-established processes by which the features of the earth's sur- 

 face are modified and developed, accompanied the advancement of 

 man from a state of barbarism to one of civilization, and is most 

 strikingly illustrated when men skilled in the arts migrate to a pre- 

 viously unoccupied region. This new factor in the earth's history 

 demands conspicuous changes in the methods of study usually 

 employed by physiographers, and makes prominent a series of inves- 

 tigations, the full significance of which is as yet obscure. The whole- 

 sale destruction of forests, drainage of marshes, diversion of streams, 

 building of restraining levees along river banks, tillage of land, 

 abandonment of regions once under cultivation; the introduction of 

 domestic animals in large numbers into arid regions, and the conse- 

 quent modification, and frequently the destruction, of the natural 

 vegetal covering of the soil; and many other sweeping changes inci- 

 dent to man's industrial development, are fraught with consequences 



