Anniversary o/'lSSB. Address of the President. 517 



itig at the general mass of his results, the account of which he has 

 been kind enough to place in my hands, I cannot help considering 

 his voyage round the world as one of the most important events for 

 geology which has occurred for many years. We may think our- 

 selves fortunate that Capt. Fitz Roy, who conducted the expedition, 

 was led, by his enlightened zeal for science, to take out a naturalist 

 with him. And we have further reason to rejoice that this lot fell to 

 a gentleman like Mr. Darwin, who possessed the genuine spirit and 

 zeal, as well as knowledge of a naturalist ; who had pursued the 

 studies which fitted him for this employment, under the friendly 

 guidance of Dr. Grant at Edinburgh, and Professor Henslow and 

 Professor Sedgwick at Cambridge; and whose powers of reason 

 and application had been braced and disciplined by the other stu- 

 dies of the University of which the latter two gentlemen are such 

 distinguished ornaments. But some of the principal of these re- 

 sults may be most conveniently mentioned, when we pass from 

 mere descriptive geology, to that other division of the subject which 

 I have termed Geological Dynamics. And this I now proceed to do. 



GEOLOGICAL DYNAMICS. 



This term is intended to express generally the science, so far as 

 we can frame a science, of the causes of change by which geological 

 phsenomena have been produced. Without here speaking of any 

 classification of such changes, I may observe that the gradual eleva- 

 tion and depression, through long ages, of large portions of the 

 earth's crust, is a proximate cause by which such phsenomena have 

 been explained : and this class of events, its evidence, extent, and 

 consequence, is brought before our view by Mr. Darwin's investi- 

 gations, with a clearness and force which has, I think 1 may say, 

 filled all of us with admiration. I may refer especially to his views 

 respecting the history of coral isles. Those vast tracts of the Pacific 

 which contain, along with small portions of scattered land, innumer- 

 able long reefs and small circles of coral, had hitherto been full of 

 problems, of which no satisfactory solution could be found. For 

 how could we explain the strange forms of these reefs ; their long 

 and winding lines ; their parallelism to the shores ? and by what 

 means did the animals, which can only work near the surface, build 

 up a fabric which has its foundations in the deepest abysses of ocean ? 

 To these questions Mr. Darwin replies, that all these circumstances, 

 the linear or annular form, their reference to the boundary of the 

 land, the clusters of little islands occupying so small a portion of the 

 sea, and, above all, the existence of the solid coral at the bottom of deep 

 seas, point out to us that the bottom of the sea has descended slowly 

 and gradually, carrying with it both land and corals ; while the ani- 

 mals of the latter are constantly employed in building to the surface, 

 and thus mark the shores of submerged lands, of which the summits 

 may or may not remain extant above the waters. I need not here 

 further state Mr. Darwin's views, or explain how corals, which when 

 the level is permanent fringe the shore to the depth of twenty fathoms, 

 as the land gradually sinks, become successively encircling reefs at 

 a distance from the shcre ; or barrier reefs at a still greater distance 



