411 
TRAPPiEAN ROCKS OF MOUNT SABLIU. 
These whetstones are very largely developed along all the western flanks of the 
Arctic Ural. The river Petchora traverses them between 64° and 65° north latitude, 
and the huge blocks of grit found near the mouth of the Ussa, where that river 
empties itself into the Petchora, prove their persistence beyond 6G° north latitude. 
From its conformable junction with the inferior limestone, the plants which it con- 
tains, and its mineralogical identity with the grits of Artinsk, before described 
(p. 129), we consider this rock to be a true member of the Carboniferous system ; 
and we unhesitatingly distinguish it from the Permian grits above the Zechstein, 
which, however, we admit sometimes much resemble it. 
The same succession of rocks which has just been described, extends probably 
to more northern points of the Arctic Ural, at least we have seen specimens of 
slaty schists, grey limestones with Catenipora escharoides (unquestionably, there- 
fore, Silurian), as well as carboniferous limestone from the banks of the river 
Ussa. 
We may here request our readers to consult the Map, and remark that the prin- 
cipal crest of the chain changes its direction in north latitude 65°, and ranges to 
its termination north-eastwards into the high mountains of Obdorsk, containing 
powerful plutonic rocks to which we have before adverted, as having been ex- 
plored and their geographical position fixed by M. A. Erman. By reference to 
the map it will be seen, that a ridge of mountains, probably igneous and metamor- 
phic, extends north-north-west from the Obdorsk group towards the icy sea. It is 
still unknown, however, whether the meridian and pal?eozoic zone of the chain is 
expanded near that parallel, where it passes into the Isle of Vaigatz, or whether a 
particular and less elevated branch there extends to the sea^coast ; though, as before 
said, we are assured by the researches of M. Baer, that the same rocks are largely 
developed in Nova Zemlia. 
Mount Sabliu . — Before we quit the consideration of the Arctic Ural, ue may 
now speak of a small trappsean crest of no great longitudinal extension, called 
Sabliu, which we found to range from between 64° 30' and 65 north latitude, and 
perfectly parallel to the major axis of the chain. This ridge, rising to a height of 
about 4000 feet above marshy low grounds, formed out of the debris of the car- 
boniferous shale and grits, is composed of a porphyritic breccia, absolutely indis- 
tinguishable from that of the Solominski-kamen, near Petrozovodsk, on the borders 
of Russian Lapland (see ante, p. 18). Ranging from south to north for about 
thirty-five versts, the ridge of Sabliu affects an Alpine form, its western slopes 
