534 Geological Society: Anniversary Address, 1843. 
the Carboniferous rocks and the Magnesian Limestone, which is so 
prevalent in the British Isles. The examination of rocks of this age 
in North America, to which I shall hereafter advert, leads to the 
same opinion ; viz., that the Permian deposits must be viewed as the 
fourth or uppermost stage of the Paleozoic series, notwithstanding 
the occurrence of Thecodont Saurians. 
Jurassic, Cretaceous and Tertiary Strata.—Overlapped as these 
Permian deposits are, in certain tracts of Russia, by red and white 
marls and sands, we are not positively prepared to state (in the 
absence of decisive fossil evidences) whether some of them may not 
represent the Trias; though the fossiliferous limestone of Monte 
Bogdo, in the steppe of Astrachan, is probably of this age. With the 
Jurassic strata, however, which follow, and which occur at in- 
tervals from 65° north latitude to the countries south of the 
Crimea, we made ourselves well acquainted. Should the word 
Jurassic grate upon the ears of Englishmen, it is impossible to deny 
that this geographical term is much more applicable to the strata 
in question than our own word “ Oolitic,” which implies a struc- 
ture scarcely ever seen in beds of this age in Russia. Whether 
examined at Moscow or on the Lower Volga, they consist“of black 
shales and ferruginous sands, occasionally containing calcareous 
cement-stones, and thus they present a general lithological analogy 
to the Lias ; a formation, however, which is not represented in Russia, 
for the fossils are all referable to the groups extending from the 
Inferior to the Upper Oolite, and many of them are identical with 
British species. 
I must now pass over the Cretaceous deposits which occupy 
such broad spaces in Southern Russia, the Lower Tertiary beds, 
some of which, on the Volga, might almost be mistaken for those 
of Bognor and the London basin, and also the strata of the 
Miocene age, which occupy wide tracts in Volhynia and Podolia, 
merely remarking by the way, how the recent discovery in limestone 
of an herbivorous Cetacean (to which I shall elsewhere allude) is a 
very important addition to the fauna of that period. 
Superficial Detritus— Ural Mountains, §c.—The discovery of ac- 
cumulations containing recent shells of Arctic species, considerably 
to the south of Archangel, was important, as showing that the great 
northern blocks, which overlie them there, were brought to their 
present positions during a period which differed remarkably from the 
one preceding it, and also from that which has followed it, in the 
very general prevalence of a colder climate over large spaces ; thus 
enabling us very safely to infer, that the great erratics of the North 
were transported in icebergs, which floated in an arctic sea and 
oceasionally grated along its bottom. But this operation, gigantic 
as it was, had its well-defined southern limits, as is beautifully 
proved by the general survey of the Russian Empire ; in the southern 
half of which all such erratics cease, and fine black slime (tchor- 
nozem) takes their place. Wherever the recent accumulations of 
the steppes indicate the desiccation of brackish seas, which like 
the present Caspian were inhabited by Mollusca requiring a warmer 
