624 [April 30. 



Popofka, thus demonstrating that wherever these usually hori- 

 zontal strata have been really affected by a line of transverse 

 fissure, their effects are by no means limited, but have ex- 

 tended athwart the sedimentary masses for considerable spaces. 



Li truth this is just what we might expect to see at intervals, 

 even in sediments like these, which, on the whole, have been so 

 equally upheaved and depressed, that, as before observed, the 

 lower Silurian are conformably overlaid by Devonian beds — the 

 relative age of the masses being alone determinable through a close 

 and rigid examination of the organic remains. In general, how- 

 ever, such abrupt curvatures and breaks are very rare, broad 

 undulations only being the predominant features of movement in 

 the unaltered paleozoic deposits of Russia. This general horizon- 

 tality of the strata was formerly sufliciently dwelt upon, and it was 

 even shown that limestones of the Permian age, on the Vaga and 

 the Dwina of north-eastern Russia, are so perfectly conformable to 

 certain pleistocene deposits, that a person unacquainted with 

 organic remains might suppose the upper palaeozoic rock to have been 

 there actually succeeded without any interval by those accumulations 

 in which the shells are to a great extent undistinguishable from, 

 those now living in the sea. Such very conformable appositions 

 of strata of different age are however most apparent wherever the 

 country is flat, and the deviations from such rules are usually found 

 where the ground rises. Thus the plateau of Czarskoe Celo, with 

 its conterminous hills of Duderhof, is high in relation to the 

 adjacent plains. Thus, again, in the Valdai Hills, which con- 

 stitute the only considerable elevation in the region south of 

 St. Petersburg, such transverse fissures are still more striking in 

 the carboniferous limestone, though difficult to observe from the 

 great masses of superficial detritus ; thus seeming to prove that in 

 proportion to the strain to which the strata were exposed in the 

 process of elevation, so were they disrupted at right angles to the 

 chief line of tension. After these allusions to the probable con- 

 nection between the transverse fissures and breaks observable in 

 the palasozoic strata of the Baltic provinces of Russia, and their 

 elevation, I will conclude this memoir by stating as one result of 

 the examination of the fossils of Scandinavia, that as the lowest 

 fossiliferous rocks of that tract are unequivocally of the same age 

 as the lower Silurian rocks of Great Britain and America, so the 

 deposits which occupy the governments of St. Petersburg and 

 Reval are the same as those of the continent of Sweden ; in the 

 latter country (I speak now of its central mass) no Upper Silurian 

 having yet been discovered. 



In both countries it would appear (the central mass of Sweden 

 only being alluded to) that this group, proved to be protozoic by 

 its having been deposited on antecedent crystalline and azoic 

 rocks, is uncovered by Upper Silurian, though the latter deposit 

 is copiously and unequivocally exhibited in the great island of 

 Gothland on the Swedish side, and in the smaller isles of Dago 

 and Oesel, near the Russian shores. Thus it would seem that 



