DANA CENTENARY 65 



3d. He must know what other workers have clone, and he ahle to utilize to 

 advantage their work and conclusions. 



4th. If he is a great geologist he must possess a creative imagination and be 

 master of both inductive and deductive methods of reasoning. 



5th. He must have staying power. 



Now, I have found no man, in my readings on American geology, who pos- 

 sessed these qualities to the same degree as Dana. In turning through that 

 masterly compendium which has come edition after edition from his hand one 

 can but be impressed with the grasp he had on the literature in all its phases : 

 how no writer, however humble or amateurish, was overlooked if his work 

 was of value, and how, notwithstanding the mass of detail, often contradictory 

 and inconclusive, the conclusions drawn were always clear and logical. 



Dana, almost from the beginning of his career, showed a capacity for the 

 larger problems, but by no means ignored the smaller ones. He was no mere 

 closet geologist or describer of species; neither was he parasitic on the work 

 of others. In no other branch of science than that of geology can it be said 

 with a greater degree of truth that "a thought is his own who kindles new 

 youth in it." Thus Dana made others' work his own, absorbing into his mind 

 the results of all laborers in the field and putting into them new youth. "And 

 we call a thing his in the long run who utters it clearest and best," wrote 

 Lowell, and he could not have better expressed it had he known Dana and 

 written it with him in mind. 



If any who are present tonight will read the writings of Dana, and particu- 

 larly those that appeared in the American Journal of Science and the two- 

 volume report of the Wilkes Exploring Expedition, and note the careful, de- 

 tailed manner in which his facts are presented, and the calmly .indicia 1 method 

 of disposing of them, I can but feel that they will agree with me in consider- 

 ing him the master mind of his time. It needs but a glance at his bibliography 

 to show us his mental breadth. I will quote a few titles, selected almost hap- 

 hazard, by way of illustration : 



On the areas of subsidence in the Pacific, as indicated by the distribu- 

 tion of coral islands. 1843. 



On the analogies between the modern igneous rocks and the so-called 

 primary formations, and the metamorphic changes produced by beat in 

 the associated sedimentary strata. 1843. 



He showed in this second paper (1) that the schistose structure of gneiss 

 and mica slates is no satisfactory evidence of sedimentary origin; rl) that 

 some granites having no schistose structure may have a sedimentary origin. 

 and (3) that the heat-producing metamorphism was not applied from beneath, 

 by conductivity from some internal source, but through the heated submarine 

 volcanic waters of the ocean. In other words, the rocks were not hypogene, as 

 explained by Lyell, but epigene. In favor of (1 ) lie showed that many lavas 

 had an original laminated structure; that when crystals of any mineral form 

 simultaneously they tend to assume a parallel structure; faces of tike cleavage 

 lie in the same direction. The unequal rectangular planes of fracture in 

 granitic rocks correspond, therefore, with the cleavages of the contained teld 

 spar. Though written in L843 more than sixty years ago this paper ma\ be 

 read with profit by the student of petrology today. 



V— Bull. Geol. Soc. Am., Vol. 84, 11)1:: 



