538 GEOLOGY. 



" Northward the star of empire takes its way " is quite as true as the 

 more familiar apothegm, and carries a more obvious causal suggestion, 

 that of the need of a progressively higher degree of stimulus from low 

 temperature, as man increased the means of his control of natural 

 agencies. The modern movement has also been somewhat more toward 

 mildly humid and forested regions, perhaps because man's superior 

 resources have led to the removal of their deterrent features, and have 

 permitted a larger utilization of their advantageous ones. It is also 

 a question whether, at the present stage of the development of man's 

 nervous organization, a somewhat less stimulative atmosphere may 

 not best conserve his energies, and give steadiness, persistence and 

 endurance to his sufficiently aggressive endeavors. The comparative 

 results that shall arise from the different physiographic conditions in 

 North America, where the same race under the same institutions is 

 subjected to wide ranges of barometric states, temperatures, air-move- 

 ments, humidity, and topography, may well be watched with interest. 

 The exceptionally rapid evolution of the American people, an off- 

 shoot of the older peoples of the Eurasian Occident, and the similarly 

 rapid evolution of the Japanese people, in some sense an offshoot of 

 the more ancient peoples of the Eurasian Orient, are to be studied 

 on their own special grounds. 



A basal factor in all this early evolution of civilization was the 

 productiveness and availability of the soil. The passage from the 

 condition of hunters and fishers, scattered necessarily to adjust them- 

 selves to the distribution of game, and shifting with its changes, or 

 from that of simple herders in sterile tracts, roaming with the changes 

 of pasture, in both cases deprived of the evolutionary influences of a 

 fixed abode and of a permanent social and civil organization, was 

 essentially dependent on agriculture, and was hence largely controlled 

 by the permanent fertility of the soil, conjoined with suitable climatic 

 conditions. And so, conversely, among the agencies that have forced 

 the migration of centers of civilization, loss of soil or of soil-fertility, 

 is one of the more important. In the lower latitudes, the upland 

 soils are usually but the residue left by the decomposition of the under- 

 lying rocks which has not been removed by surface-wash. Its depth 

 is usually quite limited. With cultivation, wash and wind-drift are 

 accelerated, and unless ample preventive measures are employed, as 

 has not usually been the case in past history, the soils are at length 



