JAMES DWIGHT DANA 251 



friend's conversion. The accession to the ranks of the evolu- 

 tionists of one whose learning was so vast and varied, whose think- 

 ing was so conservative, and whose spirit was so devout, was a very 

 potent factor in promoting the acceptance of the doctrine among 

 thinkers outside the ranks of scientific specialists. 



Valuable as were the investigations of Professor Dana in miner- 

 alogy and in zoology, his great work was in geology. The last 

 three decades of his life were devoted almost entirely to that science. 

 After the publication of the fifth edition of the System of Miner- 

 alogy, in 1868, he scarcely published anything outside of the field 

 of geology. No other science was so well adapted to the tastes 

 and capabilities of a mind so strongly disposed to broad views of 

 comprehensive relations. As Dana himself remarked, "Geology 

 is all the sciences combined into one." In such a science such a 

 mind might well find its chosen field. 



The Manual of Geology, has been since its first publication 

 the one indispensable book of reference for any American geolo- 

 gist. Apart from its unique character as a manual of American 

 geology, it is unquestionably one of the best manuals of geology 

 in general. But it must not be forgotten that Dana's contribu- 

 tions to geology include more than one hundred and fifty books 

 and papers of greater or less length and importance besides the 

 encyclopedic Manual. 



Perhaps the most characteristic contribution of Dana to geology 

 was in rendering more clear and definite the conception of the 

 scope and significance of the science. There is a little exaggera- 

 tion in Le Conte's statement that "geology became one of the 

 great departments of abstract science, with its own characteristic 

 idea and its own distinctive method under Dana." 1 Yet the state- 

 ment contains an important truth. More or less clearly all geolog- 

 ical investigators must have felt that the distinctive idea of geology 

 is that the structures shown in the rocks of the earth's crust, 

 whether on the large scale or on the small scale, whether seen in 

 the panoramic view of the landscape or discerned by the micro- 

 1 Bulletin of the Geological Society of America, vol. 7, p. 463. 



