No CrossRef data available.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
Published online by Cambridge University Press: 01 May 2009
As I have recently seen certain cases of the curious hollowing out of rocks in Corsica, described by Mr. F. F. Tuckett (with a note from myself) in the January number of this Magazine, for which Mr. Lake suggested an explanation in the following number, I will add something to that note and intimate why I did not refer to desert regions for an explanation. The case which Mr. Lake mentions (“Das Gesetz der Wüstenbildung,” fig. 7) undoubtedly much resembles Mr. Tuckett's photographs, and so, to some extent, do figs. 16 and 17, more especially the latter. With these I was not then acquainted, perhaps having overlooked the book, because I wrote a notice of “Die Denudation in der Wüste,” when it appeared in 1891, and had formed the opinion that the author was disposed to work his hypothesis for rather more than it would stand. As, however, I knew there would shortly be a chance of my getting a glimpse of the Egyptian desert, I postponed stating why I had not suggested that kind of atmospheric erosion. In this region, however, I saw no more than I already knew, but on our return, owing to an unexpected change of plans, we spent an afternoon and part of the next day in harbour at Ajaccio, when, by a lucky chance, I hit upon some curious instances of erosion, which I think may be worth a brief description.
page 388 note 1 A thin slice shows the rock to be, for a granite, in good preservation. Enough to say that it consists (apart from minor details) of quartz, biotite, and felspars, some of which (probably orthoclase), by enclosing smaller crystals of another species (usually a plagioclase), and by a peculiar mottling and streaking (perhaps a result of strain), recall the felspars of one or two Alpine granites, such as the protogine of the Mont Blane range or that on the upper part of the St. Gottbard Pass.
page 389 note 1 Perhaps it was part of the Salario Road. I had no map of Ajaccio.
page 389 note 2 The majority were wild olives, as Sir W. T. Thiselton - Dyer, afte a specimen, has kindly informed me.
page 390 note 1 See GEOL. MAG., 1869, Pl. XVII, and the Fig. on p. 486.
page 390 note 2 In a specimen obtained from a block on a more exposed part of the hillside, in which was one hollow, the cleavage-planes of the larger felspars still reflect light fairly well.
page 391 note 1 I was set on the track of this and other references by Sir A. Geikie's valuable “Text Book” (p. 456). Professor Reusch also published in a Christiania scientific periodical (1878), but I have not been able to consult the paper.