490 Geological Society. 



The Memoir, of which the following is an abstract, is the result 

 of a journey through the Northern and Central Governments of 

 Russia in Europe, made during the summer of 1 840, a verbal account 

 of some of the chief points of which, accompanied by a new geo- 

 logical map of those regions, was offered to the public at the meet- 

 ing of the British Association for the Advancement of Science, in 

 September 1840. 



Introduction. — The authors preface their memoir with a sketch of 

 the condition of geological knowledge concerning the flat and cen- 

 tral countries of Russia in Europe anterior to their visit, and show 

 that the early efforts of Strangways* had not been followed up by 

 any connected attempt to establish the classification and succession 

 of the older sedimentary deposits on the true principles of the order 

 of their superposition, and their distinctions by organic remains. 

 They point out, however, that certain elements of the subject had 

 been prepared ; first, by the map and descriptions of Strangways | 

 secondly, by the publication of the palseontological works of Fischer 

 de Waldheim, Pander, and Eichwald ; thirdly, by the recent re- 

 searches of Colonel Helmersen in the Waldai Hills ; and fourthly, 

 by the important zoological distinctions indicated by M. Leopold de 

 Buch, who, on hearing of the plan of the voyage of the authors, ex- 

 pressed his belief (from the examination of certain fossils alone) that 

 the triple subdivision of the palccozoic rocks into the Carboniferous, 

 Old Red, and Silurian systems, as indicated by Mr. Murchisonf, 

 would be found to prevail in Esthonia, Livonia and Courland. 



After alluding to the vast importance to the Russian empire of a 

 correct knowledge of the subsoil of these flat regions, the authors 

 explained the scheme which they had devised, before they left their 

 own countries, for ascertaining the data required. Aware of the two 

 great difficulties which are opposed to the examination of this region, 

 — -the slight altitude of the masses above the sea, and the vast quan- 

 tity of drift or the slight superficial detritus which obscures the fun- 

 damental rocks, — they overcame these obstacles by examining, in 

 succession, the banks of the rivers between the longitude of St. 

 Petersburgh and of Archangel, which, flowing from N.N.W. to 

 S.S.E., or transverse to the only apparent lines of elevation, might 

 be expected to offer the evidences required. They also ascended the 

 great Dwina, from the White Sea to Oustiug Veliki ; and afterwards 

 extended their researches to the south of Nijnii Novogorod, in order 

 to determine the relations of the secondary rocks to those older 

 deposits with which they had become familiar. 



In terminating these introductory explanations, the authors dwelt 

 with pleasure on the valuable assistance they had received, particu- 

 larly in the early part of their tour, from the Baron A. de Meyen- 

 dorf X, now executing, by order of his Imperial Majesty, a statistical 

 survey of Russia, who endeavoured to combine geology and natural 

 history with the chief object of his expedition by attaching to it two 

 excellent naturalists, Count Keyserling and Professor Blasius. They 



* Geol. Trans., First Series, vol. v. ; Second Series, vol. i. 



f Silurian System and map. J Assisted by M. Zenofief. 



