EXCURSIONS OF THE GEOLOGICAL CONGRESS. 231 



upper Jurassic and the Cretaceous and connecting the two; so that 

 there is not in Russia any such gap between these systems, in his 

 view, as is recognized in western Europe. The fauna, however, 

 requires more detailed study before positive results can be assured. 

 He gives much space to this discussion, in which we can not follow 

 him here. 



The Jurassic beds below present a close correspondence through- 

 out the whole of central Russia to those of the north and west of 

 France, and no marked differences can be observed. 



The Trias and the Permian are here wanting, and the Mesozoic 

 rocks lie directly on the limestones of the " Etage Moscovien " of 

 the middle Carboniferous. Both are fairly rich in fossils, and at 

 the base of the Callovian is a conglomerate in which characteristic 

 Callovian fossils are intermingled with rolled fossils of the under- 

 lying Muscovian. 



In the journey southward and eastward, from Moscow to Riazan, 

 Penza, Samara, and Oufa, these same rocks occupy the greater part 

 of the way, with much of interesting discussion, until some other 

 features begin to appear as the route approaches the Volga, which 

 it follows from Syzran to Samara. The lower Quaternary bowlder 

 clay begins to disappear and gives place gradually to an upper series 

 of deposits of mingled fluvial and seolian character, the most marked 

 of which are the " loess " and a heavy " terrace clay " of the valleys, 

 with a variety of intermediate types. 



At Syzran the general uniformity of the structure is broken by 

 an anticlinal elevation, in a north-to-south course, crossed by an 

 important line of fault, west-northwest and east-southeast. These 

 movements have produced a line of hills, which have deflected the 

 course of the Volga, and are the only examples of the kind in this 

 extensive region. Professor Nikitin places the period of their ele- 

 vation in the early Tertiary. 



At this point a very interesting feature first appears the occur- 

 rence of deposits laid down by the former extension of the Caspian 

 Sea. They are first seen near Syzran, in a baylike portion of the 

 valley of the Syzran River, and thence become more marked in 

 traveling eastward. They are chiefly clayey sands and conglomer- 

 ates, with rolled pebbles of the underlying Cretaceous rocks. They 

 appear on the divides and higher portions of the banks of the Volga 

 and its affluents, and are evidently older than the " terrace clays " 

 of the upper Quaternary. At many points they contain brackish 

 water shells of late Caspian type. We have here the evidence of 

 the Pleistocene extension of the Caspian waters over the great valley 

 of the Volga as far north as latitude 53, and even farther. 



Crossing the Volga near Samara, the route enters upon a wide 



