EXCURSIONS OF THE GEOLOGICAL CONGRESS. 235 



themselves are altered peridotites. These facts are not actually 

 new, but they are recent and little known. 



Especial interest gathers around two great mineral and mining 

 centers Miask, at the southern base of the Ilmen Mountains, and 

 Tagilsk, toward the northern part of the route, near Ekaterinbourg. 

 The rocks of all this region are metamorphic and intrusive, of great 

 variety, and are described in some detail. At times the limestones 

 are not so changed but that they retain determinable fossils (De- 

 vonian). The Miask region is remarkable for the varied and in 

 some cases peculiar character of its rocks and the great number of 

 minerals contained in them; the locality is celebrated in this respect, 

 but can not be dwelt upon here. The Tagilsk region is notable for 

 its great iron and copper mines; the former are magnetite masses 

 so intimately associated with porphyry that Professor Karpinsky 

 can only regard them as of similar and contemporaneous origin. 

 There are several great mines in and around the rather isolated 

 porphyry hill, Mount Wyssokaia; of these the oldest is that of 

 Nijni Tagilsk. Adjacent to it, below the hill, is the copper mine 

 of Mednoroudiansk, which has furnished all the beautiful Siberian 

 malachite so familiar in collections and in Russian works of art. 

 Unfortunately, the name of the iron mine, Nijni Tagilsk, has so long 

 been connected with the malachite that the error can scarcely now 

 be corrected. This name, however, is that of the district as well, 

 and so may be used for the copper locality in a general sense. 



The copper ores are a later deposit, amid tufas connected with 

 the porphyry of the hill. 



From these points the railroad turns westward, crosses the main 

 Urals, here not very elevated, and gradually descends to the city of 

 Perm. The route traverses much the same succession of rocks, in 

 reverse order, as was described irj approaching the mountains from 

 the east. This portion is treated of by Professor Krasnopolsky, and 

 the steamer route on the Kama and Volga to Nijni Novgorod by 

 MM. Stuckenberg, Nikitin, and Amalitzky. All these contain 

 much of geological and geographical interest, but there is not space 

 to go into further particulars. 



From Nijni Novgorod, the city of the great annual fair, where 

 fine sections of the several horizons of the Permian are directly 

 covered by Quaternary loess-like clays, the party returned to Moscow. 

 Here we must close this very hasty sketch, which can only give the 

 faintest idea of the extent and interest of the tour through regions 

 so little known and so little accessible to the majority of geological 

 students. 



