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Proceedings of the Royal Society 
plynthite, which may here represent an overflowed and burnt layer 
of clay-soil. I also imagined that I could with a binocular make out 
other beds of the same fissile clay as that which, at the cliff foot, 
holds the plants. 
As there was a gentle dip towards the south-west, I was prepared 
to find that one or other of these beds had come down to the water 
edge ; to form, when puddled by the waves, the so-called fuller’s 
earth; — and this was very much the true state of matters. A washed- 
out dyke, conjoined with a small fault, has formed a “ geo,” ter- 
minating in a cave. At flood-mark the waters stand in part of this 
cave. Surface waters are also constantly sapping into it from above ; 
making it more ample, by reducing to pulp, and carrying away the 
exposed edge of a bed of much the same rock as that which has 
been already noted as carrying the leaves. The fuller’s earth was 
found to be, at the time of our visit, of about the same consistence 
as pea-soup. By taking portions of the dry bed, pounding them, 
floating off in water, and sedimenting, I made some, — decidedly 
superior to the native article. A sample of this I sent to the 
Museum. 
The Pitchstone- Porphyry River of the Scuir of Eigg. 
The pitchstone plug of the river-canon of Eigg, forming the 
singular Scuir, — picturesque from certain points of view, weird and 
fantastic from others, — should be about equally well known to 
scenery hunters and to geologists. The filled-up water trench is not 
of great length ; somewhere about two miles, as its historian tells us. 
This is but a short junk of such a mighty river as that must have 
been, which cut a channel at least 400 feet deep and about 1000 
wide. As the eye ranges over a wide expanse of ocean at the spot 
where this pitchstone cast is shorn off at the west , — and as no remain- 
ing fragment of the widespread lands from which its waters must 
have been gathered on the east , now remains, — there seemed to be 
but little hope of our collecting any further fragments of its history. 
Chance threw the writer upon one such fragment. I was looking 
for boulders everywhere ; Mr. Harvie Brown was looking after grey 
seals, and birds’ eggs, grey, green, or blue; and so we landed upon 
Hyskier. Hy shier — that is, the High Skerry ; only 40 feet, but 
high enough to afford some sort of a shelter to boats which might 
