272 Scientific Intelligence. 
took place through the aid of the potash (as a flux) in the shale derived 
from the decomposition of the imbedded fucoids. Murchison reasons, 
from the vast abundance of fuci in the existing seas of those regions, 
that the view is a probable one. 
Gneiss, or granitic gneiss, is stated by Murchison to be the funda- 
mental rock of Sweden, existing with often high inclinations, before 
the lowest Silurian beds began to be formed. The facts also show 
that the crystalline ridge of the Omberg, must have been upheaved 
long after it was metamorphosed and rendered crystalline, inasmuch as 
the lower Silurian rocks upon the granitic, though highly dislocated, 
occur as soft shales and impure unaltered limestones and sandstones. 
The upper Silurian rocks are almost wholly absent from the main land 
of Sweden, showing that the former country had been uplifted before 
their deposition, and the same exist exclusively in Gothland. 
*« When viewing the great features of the earth,” says Mr. Murchison, 
“the geologist who compares the northern frontier of paleozoic de- 
posits of Scandinavia and Russia with that of British North America, 
recently described by Captain Bayfield, cannot avoid being struck with 
the great similarity of succession in these two vast regions. In both, 
the general range of the rocks is from S. W. to N. E. ; in both, the same 
type of lower Silurian deposits occurs, and _ rests upon more ancient 
crystalline rocks; and in both, are these strata succeeded in similar 
ascending order, by upper Silurian, Devonian, and Carboniferous de- 
posits. We may still further pursue the analogy by stating that in both 
regions, great sheets of water range more or less along the older fron- 
tier line, and lastly, that in both, large quantities of erratic blocks have 
been transported from N. to S., or from N. N. W. to 8. S. E.” 
**] will conclude this memoir by stating as one result of the examin- 
ation of the fossils of Scandinavia, that as the lowest fossiliferous rocks 
of that tract are unequivocally of the same age as the lower Silurian 
rocks of Great Britain and America, so the deposits which occupy the 
governments of St. Petersburgh and Reval are the same as those of the 
continent of Sweden; in the latter country (I speak now of its cen- 
tral mass) no upper Silurian having yet been discovered. 
7 In both countries it would appear, (the central mass of Sweden only 
being alluded to,) that this group, proved to be protozoic by its having 
been deposited on antecedent crystalline and azoic rocks, is uncovered 
by upper Silurian, though the latter deposit is copiously and unequiv- 
ocally exhibited in the great island of Gothland on the Swedish side, 
and in the smaller isles of Dago and Oesel, near the Russian shores. 
Thus it would seem that immediately after the completion of the lower 
Silurian group, these two continents were elevated and placed beyond 
the reach of the depositary influence of the sea in which the isles were 
