874 Earl Compton on the Rocks of the Isle of Mull. 
columns, as if it were a columnar dyke. Two of these columns 
stand by themselves, one having probably fallen which connected 
them with the rest. The base of thia rock, as well as of that in 
which is the great cave, is green sand, in coarse grains. The small 
arch is very irregular in its form, as will appear by the accompanying 
sketch. The sea washes through both these arches at high water. 
I should not omit to say that this account of the great arch is taken 
from its appearance on the western side, as the state of the tide 
made it inaccessible on the eastern, which as I have already 
mentioned, is lower than that on the west. I was unable t© 
proceed more than a very little way beyond the arches. Fossil 
shells appear in the green sand, but they are not numerous. 
I found in basalt, very near the arches, a red crystallised substance 
resembling felspar ; also a yellow variety of the same mineral. In 
different parts of the coast, between the arches and Carseg, I found 
in the basalt, crystallised carbonate of lime, chalcedony, quartz, 
radiated zeolite, prismatic zeolite, acicular zeolite, and analcime; 
also a bluish mineral, with the nature of which I am unacquainted, 
but I think most resembling a pitchstone. I also succeeded in 
finding on the shore some green jasper, like that from Rum, but 
coarser, and a red crystallised opaque mineral, the forms of whose 
crystals were not ascertainable. I also met with a very pretty 
variety of amorphous quartz, of a kind of violet hue, intermediate 
between the colours of amethystine and rose quartz. A little way 
inland, and behind the farm house of Carseg, has been found 
analcime, with foliated zeolite. Perhaps it may not be uninteresting 
to add, that plumbago has been recently found near Pennycross, 
several miles from Carseg. 
