1868.] MURCHisoiir — north- westeen Siberia. 3 



condensing, to form a bar to to all future outburst, and thus save 

 these vast regions from the earthquakes, dislocations, and ruin which 

 have for ages affected all those countries vrherein the issue of such 

 internal forces is not checked, and particularly vrhere great fissures 

 or deep longitudinal cracks in the crust exist. 



The Ural Mountains, lying as they do between two vast undis- 

 turbed regions, and replete as they are with many varieties of such 

 eruptive rocks, afford a fine illustration of this view. 



So also at several points around the centre of Eussia in Europe, 

 as in the environs of Petrozavodsk and the Lake Onega in the north, 

 and in the region of the Southern Steppes. 



It is within these zones of subterranean disturbance that the 

 huge and wide-spread deposits of Russia and Siberia exhibit un- 

 questionable proofs that they have been disturbed violently. They 

 have simply undergone equable movements of elevation and de- 

 pression, and exhibit strata of very high antiquity, often covered 

 with Postpliocene and arctic deposits, which, if we judged merely 

 from the conformity of their mutual arrangement, might be supposed 

 to be of the same or nearly the same age, though in reality they 

 were separated by long epochs in time. 



In regard to the geology of Eussia in Europe, Count Keyserling in- 

 forms me that M. Grewinck has discovered white fossiliferous chalk 

 in parts of the great Sarmatian plain, where its existence was un- 

 known owing to the cover of Quaternary and allied deposits : — 



1. At Baltishke, north-east of Kovno, and near the banks of the 

 river Noveja, where the rock is covered by 4 or 5 feet of Quaternary 

 deposit, it contains the following fossils — Rotidina trachyompJiala 

 (Reuss), CristeUaria rotulata (Lam.), Hotulina polyrapliis (Reuss), 

 Fromentulma levigata (Romer), Bulimina intermedia (Reuss), Tex- 

 tillaria glohife^^a (Reuss), Glohigerina cretacea (D'Orb.), Frondulariay 

 Dentdlina, Cytherea, of species not determined, with species of Echi- 

 noderms and large Inocerami. 2. At Melden, a country-house in 

 Courland, on the river Lendisk, below Nigrande, where, beneath a 

 cover of lignite, beds of chalk with several of the above-mentioned 

 fossils, including Inocerami, repose on Permian rocks. 



These Cretaceous rocks, separated by great distances, seem closely 

 to resemble those of Lemberg in Gallicia, and of Grodno in Russia ; so 

 that we may infer that, originally, the chalk formation had a very 

 wide extension in this region, whilst we know that it appears in force 

 low down the Volga and in the Government of Orenburg. Its denu- 

 dation in the two localities cited accounts for the great admixture of 

 chalk flint which is found in the so-called drift of these tracts. 



M. Grewinck has also made inquiries into the real source of the 

 vast quantities of amber which are found on the beach or by dredge 

 along the shore near Memel*. He suggests that it may be carried 

 down by rivers into that sea from the deposits of that age which 

 occupy the large adjacent region of Russia and Poland. I am the 

 more disposed to believe that these interior tracts are truly those 



* [On this point see Dr. Zaddach's memoir on Amber, translated in ' Quarterly 

 Journal of Science' for April. — H. M. J.] 



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