THE GEOLOGY OF THE FAROE ISLANDS. 239 
sea. If this had been their origin, we should be at a loss to account for the 
total absence of marine organic remains in the interstratified tuffs. Nothing 
at all resembling the fossiliferous tuffs of the Campagna di Roma and the Terra 
di Lavoro is to be found. Instead of these we have the coal-beds of Suderée; 
and hitherto the only fossils which the Miocene volcanic rocks of northern 
regions have yielded are land-plants, which would be inexplicable enough if 
these igneous masses had invariably been the products of submarine volcanoes.* 
The equable thickness and wide extension of the bedded basalts, which have 
been thought by some to indicate that the old lavas have been spread out 
under the weight of a superincumbent ocean, are equalled and even surpassed 
by the great lava-flow from Skaptur Jokul in 1783, which covers an area as 
extensive as that of all the Feerdées, and which in the open country does not 
average more than 100 feet in thickness. It may be admitted that the lavas 
of some modern volcanoes have “a more rugged and porous aspect” than 
many of the basalt-sheets of the Ferées—amongst which we look in vain for 
those great “ clinker-fields” and cinder-like masses which are often met with 
in the products of recent eruptions. But all modern lavas are not equally 
scoriaceous, and many have no thicker cinder-like crust than the old basalts of 
the region under review. 
While not disputing that the Feerde basalt-beds may have been poured out 
from fissures, it seems to me that the phenomena are not inexplicable on the 
view that they have proceeded from one or more foci in the manner of modern 
lavas. But if this has been the case, then it is obvious that the centre or 
centres of eruption must have been far removed from the site of the present 
islands. This, as I have already remarked, would explain the absence of 
breccias and agglomerates, of lapilliand bombs. It would also account for the 
uniform character of the ancient lavas. It is well known that in modern vol- 
canoes lavas and tufts of very different character issue at different times from 
one and the same orifice, or from craters which are contiguous. Thus a 
volcanic mountain may be built up of a great succession of basalt-rocks, 
trachytes, trachy-dolerites, obsidian, agglomerate, fine tuff, &c. And the 
basalts of modern formation do not differ essentially from those of older tertiary, 
secondary or primary age—such differences as do occur being sufficiently 
accounted for by long-continued chemical action. It is likewise true that 
trachytic rocks are not confined to modern volcanoes, but occur also inter- 
stratified with tertiary and secondary strata. We may reasonably infer, then, 
that if the Ferée basalts came from volcanic foci, and consolidated in proxi- 
mity to these, they ought to have been associated not only with coarse agglo- 
* Marine fossils are said to occur in the Surtarbrandr or lignite-beds of the sea-coast, near Husavik 
in Iceland ; but this appears to be exceptional—the palagonite-tuffs of that island being otherwise as. 
destitute of any trace of marine life as those of the Ferées. 
