TRANSACTION'S OF THE SECTIONS. 53 



bring beds of different mineral character in contact, fragments of the containing rocks 

 form a great portion of the contents of the vein. 



The portion of the mine modelled represents the richest piece of ground as yet 

 opened in these mines, and includes two extensive fault veins, together with a piece of 

 ground from which some very rich slickensides have been obtained. All the ore found 

 near the slickensides is much more refractory in the furnace, and of less produce than 

 that raised at a distance from it. The gritstone between the two veins from the points 

 where the slickensides commenced is also quite altered in its character and appearance. 



The model was on a scale of one inch to five fathoms, but the veins and a bed of 

 coal represented were on a larger scale. There was exhibited a transverse section 

 of the mining ground for 138 fathoms, a longitudinal section of eighty fathoms, and a 

 depth of seventy fathoms. 



On the PalcRozoic Rocks of Scandinavia and Russia, particularly as to the 



Lower Silurian Rocks which form their true Base. By R. I. Murchison, 



F.R.S., P.R.Geog.S., Sfc. 



The author commenced by giving a general sketch of the Palaeozoic succession in 

 Russia, showing that however perfect in exhibiting a series of Silurian, Devonian, 

 Carboniferous and Permian rocks, it was defective at its base, since between the Silu- 

 rian rocks of the governments of St. Petersburg and lleval, and the crystalline rocks 

 of Finland, there occurs a wide and deep bay of the sea ; and in tracing the lower 

 edge of the Silurian rocks from St. Petersburg to Archangel on the N.E., their junc- 

 tion with the underlying series is equally hidden by large accumulations of detritus. 

 There is also another reason why this passage cannot be made out, arising from the 

 condition of the Silurian rocks, which soft, unaltered, and, in truth, unfathomed along 

 the northern edge of the Baltic provinces, come in contact towards the N.E. with erup- 

 tive trap rocks, and have thereby undergone metamorphosis over an extensive tract of 

 country, so that on the whole the exact manner in which these ancient deposits repose 

 on the pre-existing rocks cannot there be distinctly observed. 



Scandinavia, on the other hand, presents a very clearly defined base-line, which is ex- 

 posed in different sections, both in Sweden and Norway. In illustration, the author 

 first mentioned several instances in Sweden, where the very lowest Silurian beds con- 

 taining no other fossils than fucoids, repose horizontally upon the crj'stalline rocks of a 

 more ancient period ; and he also cited localities where the lowest Silurian rocks are to 

 a great extent formed out of the detritus of those more ancient rocks. 



In the first-formed or gneissose slates of Scandinavia no organic remains have been 

 discovered. Taking into account this fact, and adopting the prevailing theory, that 

 the first solid envelope of the globe was formed under a heat so intense as to preclude 

 the possibility of the existence of animal life, Mr. Murchison proposes the term "Azoic*" 

 for this group of deposits, as expressing the fact that no organic remains have yet been 

 discovered in them. The Azoic group is immediately followed by the great palseozoic 

 series, commencing with the lower Silurian, and terminated in the ascending order with 

 the rocks of the Permian system. 



Believing however, that metamorphismhas frequently imparted a crystalline character 

 to sedimentary strata, containing organic remains, in illustration of which view he re- 

 ferred to observations he made in company with Dr. Forchhammer (see memoir in this 

 volume), Mr. Murchison alluded next to the importance of drawing a marked distinc- 

 tion between this more modern class of crystalline rocks and that which he terms Azoic. 

 He mentioned as an instance, that in Norway there are extensive transition districts 

 replete with granite, porphyry, and greenstone, all erupted subsequent to the deposi- 

 tion of the Silurian stiata, which they have altered, and which are always distinguish- 

 able from the ancient gneiss and granitic gneiss, upon which they repose. 



Referring for the further illustration of his views to a section across Sweden and 

 the Baltic Sea, to the tract of Russia east and south of St. Petersburg, Mr. Mur- 

 chison proceeded to state, that the lower Silurian rocks of both countries contain a 

 similar group of organic remains, including many species occurring in deposits of the 

 same age in the British Isles. He also mentioned that in Sweden, at least throughout 

 the central and southern provinces, as well as in the Baltic provinces of Russia, no 



* Hypozoic of Phillips. 



