49^ POPULAR SCIENCE MONTHLY 



COIXCIDEXT ACTIVITIES OF THE EARTH AXD THE SUX 



By Dr. ELLSWORTH HUNTINGTON 



YALE UNIVERSITY 



AHOXG the inorganic factors by which the fitness of the earth 

 for human occupation is most profoundly influenced, two of 

 the chief are climate, on the one hand, and telluric activity on the 

 other. To climate we owe much of the nature and depth of the soil 

 upon which all life depends; it determines the character of vegetation, 

 and makes possible the vast commerce which consists of the exchange of 

 the vegetable products of one land for the commodities of another; 

 it causes men to engage in different occupations, some, for instance, 

 raising rice in the warm plain of Egypt, and others leading the life of 

 the lumberman or trapper in the cold woods of Canada; and finally 

 climate exerts a profound influence upon human temperament, the 

 inhabitants of the torrid zone, as is generally recognized, being notably 

 less energetic than those of temperate regions. Telluric activity, mani- 

 fested in movements of the earth's crust, past and present, is equally im- 

 portant, though its effects are not so immediately visible. The ravages 

 of earthquakes and volcanoes, great as they are, fade into insignificance 

 when compared with the stupendous results which have followed from 

 the upheaval of continents and folding of thick strata of solid rock. 

 If telluric processes had not throughout the ages again and again up- 

 heaved the crust of the earth, the climatic forces of weathering and 

 erosion would long ago have reduced the original continents to feature- 

 less plains of small extent compared with the present great areas of 

 land. There would be no mountains full of minerals, and the use of 

 metals would probably be unknown because none would have been 

 discovered by reason of the enormous depth of soil which would cover 

 the country. 



In the study of climate and of telluric activity, attention has till 

 recently been concentrated upon the earth. Within a few years, how- 

 ever, scientists have begun to turn to the sun to see if its changes are 

 in any way connected with changes of climate or with the occurrence 

 of earthquakes and volcanic eruptions. At first the results were nega- 

 tive. Of late, however, students of solar physics have shown that 

 there are now in progress fluctuations of climate which appear to be 

 coincident with variations in the activity of the sun as evinced by 

 the occurrence of sunspots; and the investigations of Jensen, as I shall 



