232 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 4, 



mountain, perhaps on the col, or summit of a pass through a chain 

 of mountains, we see a circular pit of 3, 6, 10, or more feet in depth, 

 and 3, 6, or even 8 feet in diameter, with sides and bottom worn quite 

 as smooth as the parts of the surface near by ; " — and the author 

 imputes their origin to the action of ice. At Wick we have a 

 "Giant's Pot" very like those of Sweden ; and, as I was very sure 

 it did not owe its origin to ice, I communicated to Mr. Chambers 

 my views on the subject so far back as June 23, 1853, as follows : — 

 '* In my rambles along our sea-margin, between high- and low-water 

 mark, I observed long ago that stones, when resting on a pivot, or 

 on two points, were kept in constant motion when under the action 

 of the sea, and the effect of this motion was a corresponding hollow 

 on the rock on which they were oscillating and rotating. All here 

 with whom I have talked on the subject are conversant with the fact, 

 and have never had a doubt on the subject. 



" To-day I was shown a hole in a rock thus formed, about 5 feet in 

 diameter at the mouth, and 4 feet deep, very smooth, and as circular 

 as if formed by the turner. This pot is on a platform of very hard 

 clay-slate, having on the north a projecting shelf about 10 feet above 

 it ; and on the south the rock is 6 or 8 feet higher than the margin 

 of the pot ; and there is a narrow entrance sea- ward. There were 

 no stones in the pot when I saw it ; but between it and the land 

 there are several that must have been in the pot, for their form and 

 that of the pot corresponded. The interior of the pot is incrusted 

 with balani, limpets, and algse ; but sometimes it is perfectly free 

 from such. 



" I half filled the pot with stones of all sizes, from an ounce in 

 weight to that of twenty-eight pounds weight or more, and from 

 the force with which the sea dashed on the overhanging cliff, and 

 then into the pot, the stones must have been kept in perpetual 

 motion, just as sand in a tumbler of water is agitated when an addi- 

 tional quantity of water is poured into the tumbler. The sea was so 

 boisterous when I was there, that I could not ascertain the effect of 

 the stones on the pot or on themselves ; but I have no doubt, when 

 I examine it with a calm sea the molluscs and algae will be found to 

 have been rubbed off, and the stones rounded, if not knocked out of 

 the pot. The Giant's pots or tubs, described at page 37 of the 

 paper, on '* Glacial Phenomena," appear exactly to correspond with 

 this pot ; and I have no doubt that they were formed by the same 

 agents, and are additional evidence that the sea has receded or that 

 the Swedish coast has risen." 



The Dartmoor "Rock-Basins," the "Kettle and Pans" at St. 

 Mary's, Scilly, the "Giant's Pots " of Sweden, and our rock-pots in 

 Caithness have, to my view, the same origin ; the process being that 

 I have described, or a modification of it. 



I may mention that I frequently visited the pot above alluded to 

 during the summer of 1853, and found that the molluscs and algse 

 were rubbed off its sides ; the stones which I had put in were chafed 

 and rounded ; but during the winter that followed, they were all 

 knocked out of the pot. Had I been able to put a large enough 



