314 



THE WONDERS OF GEOLOGY. Lect. IV. 



In Russia the white chalk is finely developed in the 

 southern steppes of the Don Cossacks ;* and Artesian 

 wells have been carried to a depth of 630 feet through these 

 strata, without indicating any change of rock. The chalk 

 at Uspensk lies in hollows of the carboniferous system, and 

 contains many well known English cretaceous shells. In 

 the royal collection at Warsaw^ are echinoderms and shells 

 from the Polish chalk, identical with our common species : 

 even the Choanites Kbnigi occurs in the flints, as in those 

 of the South Downs, f Sir R. Murchison observed true 

 chalk on the banks of the river Ural, the extreme boundary 

 of the Russian Empire. On the Volga the white chalk 

 passes through a group of clay-stones and shales, into 

 tertiary eocene strata. The surface of the chalk of Russia 

 is no where eroded as in Western Europe. 



In North America, the deposits which appear to be the 

 equivalents of the lower members of the British series, 

 contain numerous fossils of the cretaceous types, and a 

 few species which are identical. The chalk strata of 

 New Jersey, that intervene between the Alleghany moun- 

 tains and the Atlantic, resemble the sandy and argillaceous 

 beds of our gait and greensand. The overlying tertiary 

 consist of marly clays, and variously coloured sands, with 

 green particles, as in the bottom of the London clay near 

 Reading. Such is for the most part the character of the 

 series in New Jersey : and further south, in Maryland 

 and Virginia, the eocene strata are as full of green particles 

 as the cretaceous, and can only be distinguished by their 

 fossils, and geological position. \ 



* Geology of Russia, vol. i. p. 265. All the remarks relating to 

 the Geology of Russia are derived from Sir R. I. Murchison's work. 



f Medals, vol. i. p. 264. 



% See Mr. Lyell's Remarks on the Cretaceous Strata of New Jersey, 

 in his Travels in North America. Also Prof. Rogers's Address to 

 Mie Association of American Geologists. 1844. 



