W. E. Tweketrees—TJie S. W. Slopes of the Urals. 409 



4. Seven feet of grey sandstone. 5, Two feet of grey marl and 

 white sandstone, with poor copper ore. 6. Two feet of white sand- 

 stone with cupriferous beds. 7. Ked marl. 



Troitskij Mine. — 1. Twenty-five feet red clay. 2. Forty feet of 

 red sandstone q,nd marl. 3. Six feet of brown sandstone. 4. Eight 

 feet of yellow sandstone. 5. Ore bed four feet. 6. Yellow and 

 grey sandstones. 



VicTiy Nikolskij Mine. — 1. Twenty-five feet of red clay and marls. 

 2. Twelve feet of grey marl. 3. Ore bed three feet. 4. Yellow 

 sandstone three feet. 5. Red marl. 



Droojeloobny Mine. — 1. Twenty feet red marl. 2. Three feet of 

 yellow sandstone. 3. Ore bed three feet. 4. Yellow sandstone. 



5. Red clay or marl. 



All over this area there are no repetitions of the limestone. The 

 Government of Orenburg affords a truly typical display of the 

 Permian rocks. In the eastern part are the lower limestones and 

 sandstones, in the central part is the band of Zechstein limestone, 

 while the Kargalinsk area is occupied by the upper series of sands 

 and marls. 



The conglomerates of the lower division are more powerful than 

 those of the upper, which are very thin and local. No gypsum 

 has been observed in the Kargalinsk series. The homogeneous 

 limestones so prevalent near the base of the system are here 

 absent from the upper beds. The copper ore is more irregularly 

 distributed in the lower beds than in the Kargalinsk steppe. A 

 combination of these characters, apart from stratigraphical considera- 

 tions, will generally enable a practised local observer to ascertain 

 whether he is on Lower or Upper Permian ground, though of course 

 there are localities which may fairly puzzle one. I should therefore 

 be disposed to dissent from the Eev. A. Irving's view that the 

 " limestones and dolomites of the Russian series are repeated over 

 and over again through nearly its whole range." ^ In the Bielebee 

 district, in addition to the supra-Zechstein marls and sandstones, 

 intercalated marls to a small extent and thin developments of sand- 

 stones occur in the Zechstein Limestone, and that district (though 

 not the intercalated marls) having yielded to Sir R. Murchison most 

 of his Permian plants, was much emphasized by him, and has become 

 a kind of typical ground for students of the Russian Permian, while 

 I should rather insist on the rocks of the Orenburg government 

 being taken as the type. The Zechstein Limestone of Bielebee is 

 below the marls, sandstones, and grits containing bones of Saurians. 

 That some data are needed for an appreciation ot" the correct age of 

 the Kargalinsk cupriferous beds may be seen from the uncertain tone 

 of Ludwig's treatise on the Dyas in Russia.^ He says, "It is not 

 clear from Murchison's description whether the cupriferous sand 

 ores of Kargalinsk, in which silicified wood, impressions of plants, 

 PalcBoniscus and bones of Saurians have been found, belong to the 

 Eothliegende or to the beds which at Nijni Troitsk [Bielebee dis- 



' Geol. Mag. AprU, 1882, p. 161. 

 2 Geinitz, Dyas, vol. i. p. 300. 



