12 Proceedings of the Royal Physical Society. 
of the traps of Faroe, and which to me were instructive, 
as an indication of the method by which these immense 
trappean beds were deposited. It has been admitted by 
most mineralogists that calcedony is formed by the aqueous 
method, and not subjected to any violent heat ; so here we 
have a proof, that the matrix or trap was not exposed to 
igneous fusion, and that the calcedonies and zeolites were 
metamorphic after the deposition of the trap. That these 
immense beds were of volcanic origin, no one will be bold 
enough to deny ; that they were subaqueous I cannot doubt, 
by the evidence they bear of having been horizontally 
arranged by water, and that, while at a comparatively high 
temperature, they were subjected to the action of gases 
under great tension, causing the vesicular cavities which are 
now filled with calcedonies and zeolites, — the evidence of long 
continued metamorphism. That these islands have risen at 
a period when the upper layers were still, if not plastic, yet 
containing much volatile matter, is evident from the columnar 
effects seen on all their summits, caused, certainly, not by 
igneous crystallisation but merely shrinkage. These pillars 
are always, as has been often pointed out to us by our late dis- 
tinguished President, Professor Fleming, at right angles to 
the strata beneath. 
The first glimpse of Iceland, to one who has from boyhood 
made it his hope and day-dream to visit it, was certainly very 
grand and impressive, as our eyes rested on the magnificent 
Oraefa Yokul, the highest mountain in the island. But as 
our aim was more scientific than scenic, we were more in- 
terested, as we approached the great chasm or crater of Kot- 
lugja, which so, lately as 1860 devastated the whole country 
around with a deluge of mud and showers of ashes. This 
enormous rent, which we reckoned equal to the whole length 
of Glen Eosa in Arran, is evidently so steep, that the snow 
does not lie on its sides, and there it stands in gloomy 
grandeur, on the haunch of an immense ice mountain, the 
Myrdals Yokul. Skirting the shore, we were much gratified 
by the sight of one of the largest glaciers in the plain, and, 
as we commanded the whole position, had a finer opportu- 
nity than we ever enjoyed in Switzerland, of observing the 
