The Period from 1871 to 1880 21 



I have thus endeavored to sketch, in a concise and rapid manner, the history of the 

 earlier rock-formations of eastern North America, and of our progress in the knowl- 

 edge of them ; while I have, at the same time, dwelt upon some of the geognostical and 

 chemical questions which their study suggests. With the record of the last thirty years 

 hefore them, American geologists have cause for congratulation that their investigations 

 have been so fruitful in great results. They see, however, at the same time, how much 

 yet remains to be done in the study of the Appalachians and of our northeastern coast, 

 before the history of these ancient rock-formations can be satisfactorily written. Mean- 

 while our adventurous students are directing their labors to the vast regions of western 

 America, where the results which have already been obtained are of profound interest. 

 The progress of these investigations will doubtless lead us to modify many of the 

 views now accepted in science, and cannot fail greatly to enlarge the bound of geologi- 

 cal knowledge. 



Asa Gray (botany), president of the Association in 1871, delivered his 

 address as retiring president at the meeting held in Dubuque, Iowa, in 

 August, 1872. Like his predecessor, Gray limited his discussion to his own 

 field. This change from general philosophical subjects to narrower fields 

 for addresses of retiring presidents of the Association may have been due to 

 the rapidly increasing richness of science or to an increasing humility of 

 scientists, only to be carried to such an extreme in later times that specialists 

 boasted of their ignorance respecting everything outside their own narrow 

 fields. 



Gray made a journey across the continent in preparation, as he said, for 

 his address. He chose for his subject the Sequoia trees of California. That 

 he spoke about them not as an awe-struck tourist but as a scientist grap- 

 pling with the great problems of evolution of life on the earth will be evi- 

 dent from the following excerpt from his address (vol. 21, pp. 1-31) : 



One notable thing about these Sequoia trees is their isolation. Most of the trees asso- 

 ciated with them are of peculiar species, and some of them are nearly as local. Yet 

 every Pine, Fir, and Cypress in California is in some sort familiar, because it has near 

 relatives in other parts of the world. But the Redwoods have none. The Redwood — 

 including in that name the two species of "big-trees" — belongs to the general Cypress 

 family, but is sni generis. Thus isolated systematically, and extremely isolated geo- 

 graphically, and so wonderful in size and port, they more than other trees suggest 

 questions. 



Were they created thus local and lonely, denizens of California only; one in limited 

 numbers in a few choice spots on the Sierra Nevada, the other along the coast range 

 from the Bay of Monterey to the frontiers of Oregon? Are they veritable Melchizedeks, 

 without pedigree or early relationship, and possibly fated to be without descent ? 



Or are they now coming upon the stage — or rather were they coming but for man's 

 interference — to play a part in the future? 



Or are they remnants, sole and scanty survivors of a race that has played a grander 

 part in the past, but is now verging to extinction? Have they had a career, and can 

 that career be ascertained or surmised, so that we may at least guess whence they came, 

 and how, and when? 



