2 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 11, 



In alluding to the highly important researches of that good 

 palaeontologist Schmidt, who has been exploring several parts of 

 Siberia, Count Keyserling states that he is of opinion that the chief 

 masses of the Secondary deposits which have been observed in 

 Northern Siberia are not, as Eichwald supposes, of Cretaceous age, 

 but that on closer examination their fossils will be found to agree 

 with those of Oolitic or Jurassic type, of which an account is given 

 by Keyserling in ' Eussia in Europe and the Ural Mountains,' i. e. 

 the remains derived from the Petchora region, which is the next 

 adjacent tract on the west to the Siberian region in question. 



This view is maintained by the fact that Lindstrom has described 

 exactly analogous fossils from Spitzbergen, from rocks which overlie 

 Triassic deposits. At the same time it is to be noted that these 

 fossils are somewhat peculiar, and should be classed as the Arctic 

 types of the Mesozoic formations of that age. 



It has been ascertained by M. Schmidt that the banks of the 

 Jenissei, as well as those of some of its affluents, are occupied by 

 Postpliocene accumulations, similar to those which my associates 

 and self found lying on Palaeozoic limestones at Ust Yaga and other 

 places on the borders of the great river Dwina, at Archangel. 



I have called attention to these recent observations, because from 

 them we learn that the classification which my friends and self 

 applied to Russia in Europe has a still wider application, extend- 

 ing far to the Asiatic side of the Ural Mountains. That zone of 

 eruptive, disturbed, and metamorphic rocks being passed over, many 

 of the sedimentary formations which occupy wide spaces in Europe, 

 reappear again in their normal European characters, and occupy 

 vast spaces in Siberia. 



It is right to add that M. Schmidt (whose health, I regret to 

 hear, suffered much in making these adventurous journeys) has 

 come to the conclusion that Mammoths lived in Northern Siberia ; 

 for, judging from the remains of the fossil and semifossil trees of the 

 region, he infers that in the days of those huge elephants the climate 

 of Siberia was somewhat more temperate than at present, and that 

 after the Glacial epoch the cold was for a time mitigated. 



These additional data respecting the extension into Siberia of vast 

 and slightly undulating, and to a great extent horizontal and un- 

 broken formations, which each respectively occupy such wide areas, 

 lead to the inquiry what can have been the deep-seated cause which, 

 excepting along the north and south axis of the Ural Mountains, has 

 prevented the extrusion through the crust of the globe of those 

 igneous rocks which have at various periods so highly diversified the 

 outlines of numerous geological formations in many other parts of 

 the globe. 



When speculating on the intervening matter which may have 

 checked the issue of such igneous materials over so wide an area, the 

 late Leopold von Buch once suggested to me, in conversation, that 

 possibly at some very remote period a vast sheet of hypersthene or 

 other submarine volcanic matter may have so spread over the surface 

 of the lower or more central regions of the Palaeozoic deposits as, on 



