420 Mr. Murchison's Sketch of some of the principal Results 



True lias does not exist in Russia, as Von fiuch had de- 

 cided from an examination of fossils sent to him, but the Ju- 

 rassic or oolitic series is divisible into two stages. The lowest 

 of these, which is much more developed than the upper, never 

 occupies any considerable tract of country, being either dis- 

 tributed in patches, or hidden by newer accumulations. From 

 the eastern flanks of the Ural chain in the 64° of N. latitude to 

 the Caspian Sea, it preserves nearly the same mineral and fos- 

 sil characters. This formation represents the inferior and mid- 

 dle oolite. The ferruginous sands, calcareous grits, and black 

 schists of the Moskwa are of this age; and also those beds 

 which we examined last year on the Volga between Kostroma 

 and Kinshma, at Makarief upon the Unja, as well as those 

 shales and sands which we have seen this year in many other 

 localities, particularly between Arzamas and Simbirsk, between 

 Syzran and Saratoft, at Saragula, and on the river Ilek near 

 Orenbourg. 



The upper oolitic group occurs in several situations along 

 the Donetz, where it was first recognized by Major Blcide. 

 It is calcareous, often oolitic, of light yellow colour, and 

 contains many Trigonice, Nerinees, &c, which enable us to 

 compare it with the upper Jura of the Germans, or Port- 

 land and Coral rag division of my own country. 



The cretaceous system, though composed of very different 

 beds of marls, white chalk, sands and grits (sometimes green), 

 offers for the most part the fossils of the white chalk of Eu- 

 rope, such as the Inocerami (Catillus), Belemnites mucro- 

 natus, Ostrcea vesiculates, Terebratula camea*. 



Above the cretaceous system, we have not been able to dis- 

 cover in any part of Russia, except in the Crimasa, the "num- 

 mulite limestone" which there sets on, and acquires a great 

 importance in its range through Georgia, Egypt, and the 

 Mediterranean basin. 



The equivalents of the lower tertiary formations (Eocene of 

 Lyell) seem to exist in one part only of your country (S. of 

 Saratoft). On the other hand, the middle and upper ter- 

 tiaries (Miocene and Pleiocene) cover large surfaces on the 

 Lower Volga, in Podolia, Volhynia, and also along the shores 

 of the Sea of Azof and the Black Sea, where the youngest of 

 these strata, very much resembling the "upper crag" of 

 Norfolk, are beautifully displayed. 



I have not time to enter upon the numerous and inter- 



* After this letter was written, we found in the collection of Professor 

 Eichwald at St. Petersburgh, a fine specimen of Exogyra and other fossils 

 in a green sandstone from the Lower Volga, sent to him from a locality well 

 known to us, which leaves little doubt of the existence also of a true re- 

 presentative of our greensand. — R. I. M. 



