282 REVIEWS 
Copenhagen, to enable me to continue these investigations, | hope to do so 
on the lines here indicated. 
About 5500 square miles of the total area of Iceland are at present 
covered with glaciers. The country, therefore, would seem to be in a 
state of glaciation comparable to that obtaining in Scotland during the fourth 
glacial epoch as defined by Professor Geikie. Now, if Iceland were to be 
once more totally glaciated, should we term that final ice-invasion a separate 
stage of glaciation; or merely an oscillation of the existing glaciers? Would 
the present inhabited condition of Iceland be considered an interglacial 
epoch, or merely a stage of temporary glacial retreat ? 
Such considerations must be kept in view when we are discussing whether 
the old ground moraines described in this paper have been laid down by an 
oscillating ice-sheet or during separate glacial epochs. 
In Burfell two bottom-moraines are separated by 150 to 200 feet of 
basalt, on the striated surface of which the upper moraine reposes. Possibly, 
however, that basalt does not mark the lowest interglacial horizon. 
To the next succeeding interglacial horizon probably belong the conglom- 
erates of Stangarfjall, Bringa, and Hagafjall, which are supposed to be of 
fluviatile origin. Perhaps also the columnar dolerite of Stangarfjall should 
be included here. The existence of those conglomerates at such heights and 
so far inland suggests at least a very considerable oscillation of the ice-sheet. 
Moreover, we must not forget that the conglomerates in question are buried 
underneath masses of various volcanic products. [While some of the old 
gravel beds may well represent old river channels, in other places, as in 
Hagafjall and Bringa, they had more the character of lacustrine deltas or 
cones de aéjection. | 
The next interval between two glaciations is that marked by the so-called 
‘‘preglacial dolerites’’ which henceforward cannot claim to be more than 
interglacial. ‘At the time these preglacial lava beds were laid down, the 
country had pretty much the same essential contours that it has at present.” * 
But when the uppermost of the “‘ palagonite-moraines”’ (as in Berghylsfjall 
and Hagafjall) were laid down, the relief of the country, as we have seen, 
differed greatly from that which now obtains. In the interval of time that 
separates these morainic breccias from the eruption of the later lavas, the 
most radical changes in the contours of the country had been effected, chiefly 
perhaps by subsidence. The southern lowland of Iceland cannot date farther 
back than this interglacial epoch. 
It is not improbable, indeed, that the essential contour lines or surface 
features of the whole island, so far as these are older than the later outflows 
of dolerite, came into existence during this interglacial epoch. We cannot 
tell at what particular stage the later dolerites were erupted, but we know 
t Thoroddsen, Explorations etc., p. 55. 
