398 
GARNET ROCKS NEAR BOGOSLOFSK. 
did not visit in this parallel, we learn from Captain Karpinski and Colonel Hel- 
mersen, that nothing occurs but highly metamorphic rocks (talc schist and quartz 
rock) flanked on the east by lofty culminating points of syenite and greenstone 1 . 
This, in lact, is the portion of the Ural chain in which the peaks rise to the greatest 
height, the Konshakofski Karnen being about 844 toises, or upwards of 5400 
English feet above the sea. 
The tract to the east of Bogoslofsk bristles with lower ridges and points of 
intrusive rock, which though slightly diversified in outline, possesses a great 
variety of mineral structure 2 . The copper mines of Turyinsk, fifteen versts east 
of Bogoslofsk, afford a fine illustration of metamorphism, and the effect pro- 
duced on sedimentary strata by the eruption of plutonic rocks. These mines 
occur at a point where the limestone is intersected in a complicated manner by 
greenstone porphyry, between which and the limestone are not only masses of 
copper ore, but large bands of garnet rock. We specially notice the nature of 
this metamorphism, as the result of the intrusion of igneous upon sedimentary 
matter, because it confirms, upon a grand scale, a phenomenon which was admi- 
rably described many years ago by Professor Henslow, in a memoir upon the 
Isle of Anglesea 5 . In the Welsh case the altered rock is of the carboniferous age, 
1 Helmersen does not indicate any syenite towards the centre of the chain, but lays down all the 
highest peaks as greenstone and greenstone porphyry, which rocks are occasionally separated from the 
talcose and quartzose rocks by hornblende slate. 
* Besides several ores of copper, these mines have afforded silver, zinc, lead, iron, &c„ all of which 
are described by M. Rose. 
3 Trans. Phil. Soc. Cambridge, vol. i. p. 359-447. This very able memoir of Professor Henslow de- 
monstrates, what is not so clearly exhibited in the Uralian case, that a rock containing analcime as well 
as garnets is absolutely nothing more than a metamorphosed mass of shale and limestone full of organic 
remains, which had, by the influence of an eruptive rock, been converted into hornstone, jasper, and the 
above simple minerals. It is indeed very remarkable, that so far back as the year 1821, when some of the 
ablest geologists of the present day were still “ Wernerians,” Professor Henslow’s view of the whole 
structure of the Isle of Anglesea was such, that it may to a great extent be now applied to the Ural 
Mountains, like which its chief and oldest metamorphic masses are chlorite schists and quartz rocks, 
passing into greywacke (Silurian ?) and overlaid by old red sandstone, carboniferous limestone, &c. In 
the Welsh case, as in the Uralian, the strata are penetrated by trappsean rocks and also by granites, 
which, in addition to metamorphism and fractures, have given rise to a copious development of copper 
ores. The author describes in a very masterly manner every minute change which the sedimentary de- 
posits undergo in the contiguity of the igneous rocks, and shows how the old red sandstone becomes 
crystalline, the very pebbles of its conglomerate having been fused in contact with granite. He further 
points out how, through the disappearance of one mineral ingredient and the substitution of another, 
certain intrusive masses of rock necessarily acquire different names, though in respect to age and geolo- 
gical operations they can seldom be separated. The reader who will take the trouble of comparing 
