494- Geological Society. 



far into the country of the Samoiedea), a distance of not less than 

 1000 miles. This formation has also a mineral resemblance to chalk, 

 in being loaded with thin bands of flints, sometimes concretionary, 

 in which shells and corals occur. Associated with this formation, 

 on the banks of the Dwina, about 200 wersts above Archangel, and 

 south of Susskaia, are splendid bedded masses of white gypsum, 

 which, for many miles, present at a little distance all the appear- 

 ance of white limestone*. With these grand gypseous deposits, in 

 which are occasionally large concretions, two or three thin bands of 

 limestone alternate, in one of which the authors detected fossil shells 

 (Avicula) which are new to them. Other peculiar bands near Ust- 

 Vaga, which are rather higher in the series, contain a Productus 

 approaching to P. scabriculus, with Pectens and Corals. 



The carboniferous limestone of Russia is highly fossiliferous, and 

 from the normal and unaltered condition of most of the beds, the 

 fossils are generally in an excellent state of preservation. Among 

 them are many well-known British species, the lower beds being 

 distinguished by the large Productus hemisphericus so well known 

 in the same lower beds of England and Scotland ; and the white 

 beds being loaded with many of the species published by Fischer, 

 Phillips and Sowerby, such as Productus Martini, P. punctatus, San- 

 guinolaria sulcata, Spirifer Mosquensis, Cardium alceforme, Cidaris 

 vetustus, together with the abundant and characteristic Russian coral, 

 Chcetites radians (found, according to Mr. Lonsdale, in the carbo- 

 niferous limestone of Bristol, &c), and the Lithostrition fioriformis, 

 one of the most characteristic fossils of the English carboniferous 

 limestone, &c. 



Owing to its mineral aspect, the age of this rock had, till within 

 the last year, been misunderstood ; but Colonel Helmersen having 

 observed its position in the Waldai Hills and its association with 

 certain beds of coal, and having ascertained the nature of the fossils 

 through the examination of M. von Buch, he first gave out in Rus- 

 sia, that it must be considered the true mountain limestone. The 

 authors have completely confirmed this view, by ascending and de- 

 scending sections, and have largely extended it. 



Newer Red Formations. — The manner by which the authors were 

 led to believe in the existence of newer red deposits, forming a vast 

 basin in the governments of Vologda, Nijnii, Kostroma, is explained 

 at some length, by describing the ascending section of the Dwina, 

 and by details relating to the structure of the banks of the rivers 

 Volga, Okka, &c. They show that, although this great red series 

 of the central government agrees with that of the north, in contain^ 

 ing salt and gypsum, yet that it differs from the ,f old red " group in 

 the lithological and zoological character of its marls, limestones, and 

 fine conglomerates, none of the fishes or organic remains before 

 alluded to being anywhere discoverable. In expressing their sus- 

 picion that this newer red system may be found eventually to contain 

 the equivalents of the upper coal measures, lower new red sandstone 



* See M. Roberts's account of these white cliffs, which he supposed to 

 be limestone. — Bulletin de la Soc.Geol. de France, 1840, 



