ANNIVERSARY ADDRESS OF THE PRESIDENT. ciii 



the Jurassic series, resting unconformably on the rocks beneath. Above 

 the Jurassic the cretaceous series reposes. It is divided by Dr. Co- 

 quard into three parts : a. a hmestone with Chama ammonia ; b. num- 

 muHtic Hmestone (these being conformable to each other) ; and c. 

 fucoid sandstone, unconformable. The first he refers to the Neoco- 

 mian rocks, the second to the greensand, and the third to the upper 

 chalk. The tertiary rocks are considered to be represented by a 

 freshwater and by a marine deposit, both miocene and conformable 

 to each other, and by an argillaceous and horizontal formation. To 

 these succeed modern travertines, osseous breccias, bog iron, and 

 dunes. There is much detail given in the memoir : the direction of 

 the lines of elevation is noticed in accordance with the views of M. 

 Elie de Beaumont, and the paper is accompanied by several sections. 



In a letter from Boston (7th Nov. 1847), M. Desor gave an ac- 

 count of his discovery of fragments of Venus mercenaria in the drift 

 of Brooklyn, near New York, and stated that in consequence much 

 search had been made by Mr. Redfield, whose labours had been re- 

 warded by fine collections of shells from the drift around Nevv York, 

 consisting of Venus mercenaria, Ostrea canadensis, Nassa trivittata. 

 My a arenaria, Purpura Jloridana, &c., all molluscs now found living 

 on the coasts near that city, with the exception of one species, the 

 living representatives of which are found more southward, on the 

 coast of Carolina. Details are given respecting the drift of North 

 America, and of the heights at which it is found. Pleistocene clay 

 is also noticed. M. Desor observes that the shells obtained from the 

 clay of the different localities are of littoral species, and hence, to ac- 

 count for the different levels at which they occur, he considers it not 

 improbable that during the emergence of the land above the sea, there 

 was time sufficient for these species to multiply and form beds at 

 different altitudes above the present ocean level. Mention is made 

 of the probable distribution of land and water in later geological 

 times in North America, and of its consequences. 



M. d'Archiac gave a summary of the observations made on the 

 quaternary or diluvial rocks, which he defined to consist of accumu- 

 lations effected between the close of the Subapennine deposits and 

 the commencement of the modern period. It may, he observes, be 

 considered, that no one cause yet assigned for these accumulations is 

 of itself sufficient for the effects observed, while many of them have 

 concurred either simultaneously or successively, in different degrees 

 and under different circumstances, to produce the results seen. M. 

 d'Archiac refers to the first part of the second volume of his Histoire 

 des Pr ogres de la Geologic for the proofs of his opinions. 



M. Frapolli, in a summary of the first part of a work on the 

 Terrains meuhles of Europe (subhercynian type), observes, after 

 remarking on the varied production of detrital rocks, that the accu- 

 mulation of boulders and blocks, gravels, sands and clays, commonly 

 termed terrains meuhles, is not, as a whole, single and posterior to 

 deposits in beds, as has been sometimes supposed, but that there 

 have been similar accumulations during all geological periods, formed 

 on the land as well as in the sea. Taking the view of sudden marked 



