29G Memoir on the Geology of the [Ocr. 



must transcribe entire, as I think the perforations he describes perfect- 

 ly analogous to those of Makoortee. 



" At Peninis Point, St. Mary's, Scilly Islands, there is a curious 

 " example of that decomposition of granite, which antiquaries have 

 " termed rock-basins, and considered the work of the Druids. The 

 " Kettle and Pans, as these depressions are there named, occur in 

 " the large blocks of granite on the top of this promontory ; they are 

 " generally three feet in diameter, and about two feet deep and mostly 

 " circular and concave, but there are others much indented at the sides, 

 *' * Some have perpendicular sides and flat bottoms ; some are of an oval 

 " form, and others of no regular figure. Many of the blocks are six or 

 " seven yards high and eight or nine yards square, and several of them 

 " have four, five, six or more of these cavities in them. A large rock 

 " at the extremity of this group, has two basins of an immense size, 

 " besides several smaller ones. The upper and larger one appears to 

 " have been formed by the junction of three or more large basins. It 

 " is irregularly shaped and about eighteen feet in circumference, and 

 " six feet deep. When the water in this basin has attained the height 

 " of three feet, it discharges itself by a lip into a lower basin, more 

 " regularly formed, the back of which is about five feet high, but 

 " which is incapable of containing more than a depth of two feet of 

 " water, owing to the declivity of the surface of the rock.'* As a 

 " proof that similar decomposition sometimes takes place on the sides of 

 " a block, the author, above cited, mentions an oval cavity, six feet long ? 

 " five wide, and near four feet deep, thus situated."! 



I have purposely marked in italics all the words that precisely cor- 

 respond with the description of the cavities of Makoortee. I am not 

 acquainted with the opinion of Mr. Woodley regarding these cavities, 

 but that of De la Beche is that they are produced by the decomposition 

 of the rock. 



After what has been detailed, I think that the conclusion is unavoid- 

 able, that the origin of the so called rock basins in England must have 

 been analogous to that of the Makoortee erosions ; and that, at a subse- 

 quent period, by one of those catastrophes which our planet has been sub- 

 jected to, these perforations, together with the hills or low-lands, in which 

 they had been excavated, were heaved up to the altitude at which they 

 are found at present. If, by a similar catastrophe, the present Makoor- 

 tee group, should be heaved up some more thousands of feet, the Ma- 

 koortee cavities would become precisely rock basi?is. I see no difficulty 

 in supposing the nests of mica of the granite (if it be the common 



* Itevd. G. Woodley ; View of the present State of the Scilly Islands, 1822. 

 + Geological Manual, p. 46, 3d Edition, 



