Second Geological Survey of Russia in Europe. 69 



dark shales and sands of the northern and central regions. They 

 are chiefly light-coloured limestones and marls, and are charged 

 with large Ammonites resembling those of the Portland rock with 

 Trigonia clavellata, Nerinea, and other types closely allied to those 

 which occur in the upper oolites of Great Britain and the Continent. 



Cretaceous System. — This system is very considerably developed 

 in the central and southern tracts of Russia. In the government of 

 Simbirsk, where it has been closely studied and its fossils carefully 

 collected by M. Jasikof, it surmounts the Jurassic series, and the 

 same order may be seen in the governments of Saratof and on the 

 banks of the Donetz near Izium. 



Though the lithological sequence of the strata differs from that 

 of the British Isles, the system, as a whole, bears striking analogies 

 to that of the same age in Western Europe. The white chalk, for 

 example, and many of the fossils which it contains, including Ino- 

 ceramus Cuvieri, Belemnites mucronatus, and Gryphcea vesiculosa, is 

 absolutely undistinguishable from that of France and England; but 

 in the localities seen by the authors, it did not offer the same sub- 

 jacent succession of gault and lower greensand as in Western 

 Europe, though at Kursk the white chalk reposes on hard concre- 

 tionary sandy ironstone, somewhat resembling the clinkers of the 

 lower greensand of England. Nor are there any evidences of the 

 existence beneath the cretaceous rocks of the " Systeme Neoco- 

 mien " of the French geologists. Associated however with the 

 white chalk, the authors observed, particularly between Saratof 

 and Tzaritzin, many beds of marl and siliceous clay-stone, in which 

 bodies like Alcyoniee were prevalent, and at Kursk they found that 

 the white and yellowish subcalcareous marls which closely overlaid 

 the white chalk contained a Belemnite, as well as certain polypifers 

 common to the true white chalk of other parts of Russia (Volsk), 

 and hence they concluded, that some of these overlying marls are 

 possibly the representatives of the Maestricht beds of Europe. 



The white chalk alone has been pierced to a depth of upwards of 

 600 feet by an artesian shaft at the iron forges of Lugan, in South- 

 ern Russia, in which tract the deposit lies unconformably on the 

 uplifted edges of the carboniferous rocks. 



Tertiary Deposits. — The tertiary strata, as separated from diluvial 

 and alluvial accumulations, are little known in the North of Russia, 

 with the exception of the shelly strata of post-pliocene age which 

 have been described in the government of Archangel, vol. six. p. 495. 



The lowest tertiary beds which the authors personally examined, 

 are the marls with concretions forming clifts at Antipofka, on the 

 right bank of the Volga below Saratof, where they were first noticed 

 by Pallas. Among these shells are several species undistinguishable 

 from those published by Sowerby from the London clay of Bognor 

 and Hants, such as Cucullcea decussata, Venericardia planicosta, 

 Calyptrcea trockiformis, Crassatella sulcata, Turritella edita, &c. 



The middle tertiary or miocene strata are spread, it is well known, 

 over large tracts in Volhynia and Podolia, in which countries they 

 have been described or alluded to by Prof. Eichwald, M. Dubois de 



