DYNASTY OF MAN 681 



latitudes where other factors do not favor human development. 

 2. In regions of heavy glacial deposition, which fortunately include 

 the greater and the more southerly parts of the glaciated area, a 

 deep sheet of comminuted rock-material, ready for easy conversion 

 into soil by weathering and organic action, covers great plains. 

 Furthermore, the drift has a gentle relief that does not favor rapid 

 erosion. North of the border of the glaciated area in North America, 

 in a belt 400 or 500 miles wide, the subsoil of glacial flour and old 

 soil, glacially mixed, has an average thickness of about 100 feet. A 

 similar statement may be made of a large area in north-central 

 Europe. The average thickness of the residuary soils of unglaciated 

 regions similarly situated is about 5 feet. The twenty-fold provision 

 for permanent fertility thus arising from glaciation seems likely to 

 be a factor of importance in the localization of the basal industry 

 (agriculture) of mankind, and of the phases of civilization that are 

 dependent on it. 



With the evolution of the industrial arts, resources which were 

 neglected at first have come to play important parts in the distri- 

 bution and in the activities of the race, among which are the long 

 and growing lists of mineral resources. Chief among these are the 

 metallic ores, the fossil fuels, the mineral fertilizers, and the struc- 

 tural and ornamental materials of stone and clay. These now 

 influence man's distribution and activities far more than formerly, 

 and they are quite certain to be more influential still in the future. 



The distribution and activities of men recently have come to 

 be affected by the distribution of the water-power that arose from 

 the deformations of the late Tertiary periods, and the stream- 

 diversions of the glacial period. With little doubt, such sources of 

 power are to play an increasingly large part in human affairs as time 

 goes on and the stored fuels are exhausted. 



With the increasing complexity of human activities, the locali- 

 zation of the race will more and more depend on combinations of 

 resources and conditions; but it is difficult to see the time when 

 persistent fertility of the soil, under favorable climatic conditions, 

 co-ordinated with great supplies of fuels, ores, and structural ma- 

 terials, will not constitute a decisive and controlling advantage. 



Provincialism giving place to cosmopolitanism. The early 

 history of human dispersal was marked by pronounced provincial- 

 ism. Early peoples were much isolated by distance and by natural 

 barriers, and they often interposed artificial barriers against free 



