The Hon. Mr. Strangways on the Geology of Russia. 11 



one of the older rocks last described. Upon this lies a sand or sandstone, 

 of which, it has been imagined, the hard red grit of the west coasts of 

 the Onega Lake is only a more compact form. In the neighbourhood of 

 Petersburg this sand alternates with beds of shale, above which occurs a 

 thick bed of limestone characterized by the same fossils which mark the 

 limestones of Sweden and Norway, according to Von Buch. The clay and 

 sand only have yet been found north of the Neva and Svir ; the limestone 

 follows the southern outline of the lakes, and skirts the two rivers above 

 named. The sand and shale, together with the limestone, are distinctly 

 stratified ; the latter, with the sand, contains organic remains; both which 

 characters are wanting in the clay. 



These three strata, which I shall consider as making one formation, extend 

 from the Baltic isles, which connect it with Sweden, through Esthonia*, 

 the north of Livonia and Ingria, up to Vitegra, at the south-east corner of the 

 Lake Onega. As I have given a more detailed account of it in another me- 

 moir, it will be unnecessary to enlarge upon it in this place. — Vide Geologi- 

 cal Transactions, Vol. v. p. 293, &c. 



Northern Salt District. 



This formation, characterized in all parts of the globe by its striking fea- 

 tures of red marl and sand, containing subordinate beds of sulphate of lime 

 in every possible variety, as well as rock salt or saline springs, abounds 

 in the central and southern parts of Russia, The northern salt district 

 stretches in a line parallel to the Petersburg limestone mentioned above 

 for one thousand versts ; it makes its first appearance in the Isle of Osel, 

 and is worked in several parts of the south of Livonia. 



Gypsum is quarried at Diinahof, Uexhiill, and Kirchkolm. It is frequently 

 of a dark brown colour, veined with white, and in that state takes a fine polish 

 and is extremely beautiful, much resembling that called oriental alabaster. 



* The limestone of Reval contains pyrites, which is uncommon in that of Petersburg. At 

 Arrosaar, near Fellin, it contains sulphuret of lead, together with blende, in nests. These 

 minerals were worked there under the Swedish Government; but an attempt to reopen the mines 

 in 1806 was unsuccessful. The same minerals have been found also in veins traversing the lime, 

 stone of Reval. 



This limestone exists also on the very edge of the salt district next described, at Seltza Posad, 

 a village and post on the road from Novgorod to Pscov, and just within the border of the latter 

 government; also, according to Giildenst'adt, at Sukhlova, not far from Porkhof. Both loca. 

 lilies are on the river Shelon. 



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