. Geological magazine. I notice in the February number of the GeologicalMagazine a letter from Professor Bonney on the subject of atmo-spherically eroded rocks. In this connection it may be of interest toput on record the fact that hollowed rocks, apparently quite likethose described by Mr. Tuckett, Professor Bonney, and the Rev. , were met with under totally different atmospheric conditionsin the Antarctic. The examples there also occur in granite. Theyare found at an altitude of about 4,000 feet in latitude 77° 49 S.,longitude 163° E., in South Victoria Land, and at least two typesm
. Geological magazine. I notice in the February number of the GeologicalMagazine a letter from Professor Bonney on the subject of atmo-spherically eroded rocks. In this connection it may be of interest toput on record the fact that hollowed rocks, apparently quite likethose described by Mr. Tuckett, Professor Bonney, and the Rev. , were met with under totally different atmospheric conditionsin the Antarctic. The examples there also occur in granite. Theyare found at an altitude of about 4,000 feet in latitude 77° 49 S.,longitude 163° E., in South Victoria Land, and at least two typesmay be distinguished. A. In fairly normal granite. The rock is a very ordinary greyto pink granite with felspars usually about a quarter of an inch long;it appears to be quite fresh even on the surface, and has a markedsuperficial glaze on both convex and concave surfaces. The moststriking cavity is on the south and weather side of a large block, andtherefore faces away from the sun; it is about eighteen inches across. Fig. 1.âA large block of granite showing ca\dty on the south and -weather side;18 inches across at opening, diameter increasing to 2 feet inwards; depth ofcavity more than a foot. At the opening, and the diameter increases inwards to at leasttwo feet. The depth of the cavity is a little more than a foot, andthe back wall is partially covered with a hard mammillated orbotryoidal crust, the surface of which is white and harsh to thetouch. Pieces of this were brought home, and some of theseMr. Prior has kindly analysed for me: he says, the incrustationconsists mainly of carbonate of lime; there is a little silica leftbehind on solution in hydrochloric acid. The incrustation waslamellar, scarcely more than one-eighth of an inch thick on theaverage, but in the projecting botryoids, which are sometimespartially hollow, may be more. The incrustation was firmly fixedto the granite face, and it was impossible to make out whether thesurface beneath it was or was not gl
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1864
