ANNIVERSARY ADDRESS OF THE PRESIDENT. XXXV 



geologist begins. There must necessarily have been a state of our 

 earth when no sedimentary strata existed, for they could only be 

 formed by the disintegration of pre-existing rocks : the smallest 

 fragment contained in them is an indisputable witness of the truth 

 of this fundamental principle in geology. We know what the mi- 

 neral nature of these rocks must have been, from the mineral nature 

 of the strata that have been formed out of them ; but beyond that, 

 all is obscure : under what forms the materials of these rocks were 

 aggregated, what masses the aggregations constituted, how, in short, 

 the round earth was then composed, are speculations that must be 

 left to cosmogonists, for they are not within the province of the 

 geologist. But if there are fragments in the oldest sedimentary de- 

 posits, and if these fragments, whether angular or rounded, are 

 similar to those now forming: under our eyes, we legitimately infer 

 that the agents that fornj-^ ^. both were alike : if the deposits con- 

 tain the remains of ahima^^ kuU plants, we also legitimately assume, 

 that the elements necefe ry for their existence were the same as 

 those which now support animal and vegetable life; it would be 

 unphilosophical to reason on any other principle. The deposition 

 of the oldest sedimentary rocks is therefore the commencement of 

 geological chronology; from that point we trace successive steps in 

 creation, a sequence of changes, to our own time ; that far-distant 

 period forms the subject of the first chapter of the voluminous history 

 of the earth, a history recorded in documents of unerring truth ; 

 written, it is true, in a language so rich and copious as to be very 

 difficult to learn, but to interpret and arrange these documents is the 

 business and the privilege of the geologist. 



M. Elie de Beaumont, in the lectures to which I have referred, has 

 taught his pupils that the only hope of arriving at a right interpretation 

 of thepast, is by a careful study of the phasnomena subject toourobser- 

 vation, and of the laws by which modern changes in the constitution 

 of the materials of the earth's crust, and in the arrangements of its 

 several parts are governed. One of the first and most striking things 

 that arrests our attention and excites our wonder, in the study of the 

 earth's structure, is the evidence it affords of the immensity of past 

 time, of the incalculable periods that have elapsed during the slow 

 and gradual progress of its formation. Thus M. Elie de Beaumont 

 begins by showing the great duration which we must often assign 

 even to the superficial covering of vegetable soil and alluvium ; and 

 he enters at considerable length into this subject in a very in- 

 structive manner. Thus, for example, he shows that the covering 

 of vegetable soil, thin though it be, is often proved to be of great 

 antiquity ; by the evidence of ancient tumuli, of cyclopean structures 

 and druidical monuments, built on that covering, which has under- 

 gone no change since their foundation ; that is, for a period of at 

 least 2500 years, and without our being then able to assign any limit 

 to its anterior existence. As another class of evidence, he refers to 

 the instances of the great age of dicotyledonous trees, which M. 

 DeCandolle has brought forward ; one of which, a Cypress near 

 Oxaca in Mexico, he estimates to be nearly 6000 years old. " The 



VOL. III. ^ 



