646 APPENDIX I. (INVERTED STRATA IN THE URAL MOUNTAINS.) 
within the cavities of the rock. The hydrates of iron, which in many countries fill superficial cavities, 
belon" clearly to another class of phenomena, and are to be generally considered as mere aqueous 
deposits, which are of comparatively recent age. 
H. 
Palaeozoic Rocks of Scandinavia. 
Some of the fossils from Hysbifiol in Sweden have very much the aspect of being derived from the 
uppermost beds of the Lower Silurian. In stating our belief, that the chief palaeozoic strata of the con- 
tinent of Sweden are Lower Silurian, as distinguished from those of Gothland, we allude simply to the 
zone which fell under our survey. We have grounds to think, that in some places patches of Upper Silu- 
rian group will also be found to occur, as in Norway. For example, our friend Prof. Forchhammer has 
informed us that he believes there are Upper Silurian fossils in the higher part of the Aalleberg in West 
Gothland, and at Klinte in Scania. At the latter place, indeed, the occurrence of the Avicitla retrofiexa 
and other Upper Silurian fossils quite unknown in the Lower Silurian beds, has already determined the 
point. In Scania also there is a red micaceous sandstone, connected with argillaceous beds and porphyry 
(as in Norway), in which forms like Avicula and Modiola have been discovered, and which Prof. Forch- 
hammer thinks may be of the age of the Old Red Sandstone. Again, from what we saw of the specimens 
of rocks and fossils from Dalecarlia in the Museum of Stockholm, we have very little doubt that a country 
which has afforded the Lcptmna depressa, L. euglypha, and a species of the peculiar genus Brontes (Gold- 
fuss), must contain Upper as well as Lower Silurian rocks, while a portion of the sandstones which 
occupy that region may represent the Old Red Sandstone. These points we hope to be able to work out 
in the course of the ensuing summer (February, 1845). 
I. 
Inverted Strata on the Flanks of the Ural Mountains. 
In reference to this phenomenon we have shown (p. 463 et seq.), how under the conditions exhibited 
along the flanks of the Ural, it is impracticable to explain the inversion on several parallels of longitude, 
by the mere uprising of the central ridge, and the consequent overthrowing or bending back of the strata 
upon themselves. We have, in fact, endeavoured to account for the inversions at considerable distances 
from the axis, by subsidences of the fractured ends of the rocks which approach towards the issue of erup- 
tion. But even admitting our hypothetical view, that the uprising of a large quantity of molten matter 
to swell the central ridge, might occasion cavities occupied by gases only, into which the ends of the 
fractured masses might sink; why, it will be asked, do the inward edges of such masses dip towards the 
chain ? why have their external edges never been depressed ? and why are they, on the contrary, raised ? 
Now, the facts are, that the sedimentary rocks on the flanks of the Ural Mountains are fissured by a 
number of parallel north and south cracks, at some of which (as Nijny Serginsk and Bissersk on the west 
flank, and at numerous points on the east of the chain) molten matter has forced its way to the surface. 
If then we Hew the original condition of this eruptive matter when it was seeking to find a vent in its 
central or chief habitual fissure, we may liken it to a series of great subterranean waves, moving from the 
eastern and western flanks, where its issue was repressed (by the nature of the sediment and other causes), 
to that channel where it was liberated. In this way we may conceive, how the wave-lilce, upheaving 
lateral force, when applied from flanks to centre, raised up the outward ends of the fissured strata by a 
succession of heaves ; and if this hypothesis be admissible, no great depression of their inward ends is 
called for. In speculating, however, on the possible modes of explaining this phenomenon, under such 
