Page:Popular Science Monthly Volume 52.djvu/249

Rh 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 (Devonian). 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 in 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.