410 PROCEEDINGS OF THE ACADEMY OF [1897. 



Below, there is a cavernous brecciforni limestone formed of 

 fragments of limestone cemented together by calcareous matter, but 

 without fossils. It is about 83 feet thick, occurs about 4 kilom. up 

 the Volga from Samara, and forms a large part of the upper part of 

 the Mountains of Sok. Some kilometers before reaching the con- 

 fluence of the Volga and Sok the Carbonic limestone shows itself 

 beneath the brecciated limestone in the sandy beds as in the moun- 

 tains of Jegouli. The upper horizon shows Schwagerina limestone. 

 Separated from the Sok Mountains by the valley of that name is the 

 mountain or hill called Tzarev-Kourgan (Hill of the Tsar). It 

 shows in descending order from the top : Limestone with Fusulina 

 longissima and other Fusulinas, Spiriferina Tarance, and Productus 

 Villiersi. 



(d) Limestone with Bellerophon, large, as yet undetermined 

 Spirifers, Nautilus, Orthoceras. 



(c) Dolomites with Productus Cora. 



(6) Limestone of Productus scabriculus, Camarophoria crumena, 

 Meekella eximia. 



(a) Limestone of corals and bryozoans. 



The Hill of the Tsar is thus formed by the same limestones as 

 those constituting the greater part of the Jegouli, and like that of 

 the fauna of gshelien age near Moscow. 



The long distance from Samara to Oufa over the trans- Volgian 

 steppes is over the Permo-Trias and the Permian. The modelling 

 of the country is so strikingly like that of the bad lands of South 

 Dakota and other parts of the western United States that no one 

 who had seen both could fail to be struck by the resemblance. The 

 geology would seem to be of the simplest, viz. : the very gradual 

 succession of continually lower horizons from the Volga to the 

 Ourals. 



But we come unexpectedly here upon another burning question 

 which divides the geologists of the official survey and others from 

 Stuckenburg, Kratov, Netchatev, Amalitzky and still others. The 

 Geological Survey sees in these beds which it marks P T., and which 

 lie between the Permian and Trias, a series of transitional deposits 

 not closely analogous to those in similar horizons in central Europe, 

 and proposes for them provisionally the name Tartarian. The 

 opponents of this view class all the upper beds of the iridescent 

 marls as Permian. The Russian Survey recognizes two series of 

 red and iridescent rocks. The first it calls the Tartarian, which 



