126 Mr. Murchison on the Geological Structure 



one, the whole not occupying a breadth of more than from 45 to 70 

 miles, the South Ural, i. e. to the south of the mountain Jurma*, 

 expands to much greater width, branching off into fan-shaped 

 ridges, which trend to the south and to the east and west of that 

 point. In this region, however, as in the north, the water crest or 

 Ural-tau preserves a north and south direction, varying in height 

 from 1800 to 2500 feet, whilst the broken ridges on its western 

 flanks, such as the Taganai near Zlataoust, rise to 3800 English 

 feet, and the Iremel to about 5136 English feet above the sea. 



From its configuration, and also from its latitude, the South Ural, 

 inhabited by Baschkirs, is infinitely more picturesque than the North 

 Ural ; but, with the exception of the environs of Miask and Zlata- 

 oust, it is much less rich in mines than the North Ural. 



Geological Structure. — The Ural mountains consist of ancient se- 

 dimentary strata, which, in the central parts of the chain and on its 

 eastern or Siberian flank, are for the most part in a highly metamor- 

 phic condition; also of various rocks of igneous or intrusive origin. 



Owing to the eruption of the latter at numberless points and 

 along great zones of fissure parallel to the axis of the chain, the 

 ancient deposits are so dismembered and altered, that it is at inter- 

 vals only they can be deciphered. The rocks are described in de- 

 scending order, or from the flanks to the centre of the chain. 



Carboniferous System. — By examining these mountains from their 

 western slopes, where igneous rocks are comparatively scarce, the 

 authors, in consequence of their knowledge of the palaeozoic strata 

 of western Europe and Russia in Europe, had no great difficulty in 

 reading off the true order of succession on the banks of the Tchus- 

 sovaya, Serebrianka, and other transversely-flowing streams. In 

 the first place, the beds of sandstone, conglomerate and calcareous 

 flags alluded to in the former memoirf are seen to rise from beneath 

 the Permian deposits, and containing in some parts thin courses of 

 coal, and in others coal-plants, Goniatites and certain fossils, re- 

 present the upper members of the carboniferous system. These 

 strata are succeeded by a thick formation of hard quartzose grit 

 and sandstone, very much resembling the millstone grit of some 

 parts of England. Beneath this is the carboniferous or mountain 

 limestone, properly so called', of English geologists, and which is 

 recognised by containing many of the same typical fossils as in En- 

 gland and other parts of Russia. Thus defined, the carboniferous 

 system occupies, on the western side of the chain, a very wide zone, 

 which to the south of Kongur is expanded into a large trough ex- 

 tending beyond the parallel of 55° N. lat., and flanked upon the 

 west and east by upcasts of the limestone, it contains in its centre the 

 great undulations of the grits and conglomerates just spoken of. 



A third and less prolonged, but most remarkable zone of this 

 limestone appears in four insulated hills extending north and south 

 of Sterlitamak, and perfectly parallel to the chain. It is in the 



* About 3000 English feet above the son. All these heights are taken 

 from Colonel Helmersen and M. Hoffmann. 

 f See pres. vol. p. 64. 



