GEOLOGY. 



RECENT PROGRESS IN GEOLOGY. 



Of the geological changes still in operation, none are more remarkable than 

 the formation of deltas at the mouths of great rivers, and of alluvial land by 

 their overflow. Of changes of the latter kind, perhaps the most remarkable 

 is the great alluvial deposit formed in the valley of the Nile by the annual 

 inundations of that river ; and here it fortunately happens that history comes 

 to the aid of the geologist. These sedimentary deposits have accumulated 

 round the bases of monuments of known age ; and we are, therefore, at once 

 furnished with a chronometric scale by which the rate of their formation may 

 be measured. The first of the series of measurements undertaken by Mr. 

 Homer was made with the co-operation of the Egyptian Government, 

 around the obelisk of Heliopolis, a monument built, according to Lepsius, 

 2300 vcars u. c. A more extensive scries of researches has been since tin- 



m 



dertaken in the district of Memphis ; but Mr. Horner has not yet, I believe, 

 published the results. The problems now to be solved in Palwonlolotjy are 

 clearly defined in the enunciation of the problem recently proposed by the 

 French Academy of Sciences as one of its prize questions, viz., "to study 

 the laws of distribution of organic beings in the different scdimentarv rocks, 



O O / ' 



according to the order of their superposition ; to discuss the question of 

 their appearance or disappearance, whether simultaneous or successive ; and 

 to determine the nature of the relations which subsist between the existing 

 organic kingdom and its anterior states." The prize was obtained by Prof. 

 Bronn, of Heidelberg ; and his Memoir, of which I have only seen an out- 

 line, appears to be characterized by views at once sound and comprehensive. 

 The leading result seems to be, that the genera and species of plants and 

 animals, which geology proves to have existed successively on our globe, 

 were created in succession, in adaptation to the existing state of their abode, 

 and not transmuted, or modified, as the theory of Lamark supposes, by the 

 physical influences which surrounded them. Address of the President 

 British Association for 1857. 



BAYOUS AND DELTA OF THE MISSISSIPPI. 



From a paper recently read before the New York Geographical Society, 

 by Erastus Everett, Esq., of New Orleans, " on the Bayous and Delta of 



