416 SIR RODERICK I. MURCHISON'S ADDRESS. [May 25, 1857. 



remote periods, or now in progress. Once let tlie two points of this 

 simple view be established, and we may extend the reasoning to 

 those periods of change in the surface of the globe when, after the 

 former sea-bottoms were raised up to constitute the mass of the 

 present continents, great lines of cliff were formed in given direc- 

 tions, facing, as it were, broad, low tracts, covered by marine 

 drift. 



" How is it," said a native of the country to me, when I w^as 

 formerly travelling in Eussia, "that the Volga has always its right 

 bank lofty and precipitous, and its left bank low ? " The question 

 was startling ; but, in examining the rocks of the mightiest of 

 European streams, I found that it was true, though the course of 

 the stream varied more than the fourth of a circle in the two 

 main directions which it followed. Descending along the high or 

 right bank from Nijny Xovogorod to Kazan, I did, indeed, speculate 

 upon its having been the ancient shore of a sea which covered the 

 lower country to the north ; and if we adopt the law that the pre- 

 cipitous face was the side exposed to the waves, the prevalent 

 wind in that region, at a period antecedent to the creation of the 

 human race, must have proceeded from the north. 



This phenomenon, of a precipitous face exposed to the north, con- 

 tinues from the confluence of the Oka and Volga on the west, to 

 Kazan on the east, a distance of upwards of 200 miles. Throughout 

 that space, headlands of red sandstone and marls stand out on the 

 right bank, opposed, in a striking manner, to the low country on 

 the left or northern shore. Again, whilst not a single northern 

 erratic block is to be found to the south of this portion of the Volga, 

 the low country, at a little distance to the north, is covered by those 

 great erratics, all of which, as geologists know, were transported 

 by ice-floes from the north, and dropped upon the bottom of a 

 former sea. We may, therefore, naturally infer, that this east and 

 west line of cliffs was formed during the icy period, when the gi-eat 

 northern currents prevailed, the waves of which lashed against the 

 hills extending from Nijny Novogorod by Tcheboksar and Sviask 

 to Kazan. 



On the other hand, when the same great stream turns abruptly 

 to the S., and trends even to the S.S.W., a line of cliffs, still on the 

 right bank, ranges from the bold headland of Carboniferous Lime- 

 stone near Samara, and extends for about 550 miles to near Tzaritzin, 

 facing the E.S.E. and S.E. Now, it is to be noted that, in front 

 of this line of cliff, the low country on the opposite bank of the 



