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| Keywords: The Quarterly journal of the Geological Society of London (12711590663).jpg 1855 <br> FORBES FOLIATION OF ROCKS <br> 173 <br> case in which the Unes of fohation are carried out quite independently <br> of the nature of the minerals hy which they are formed <br> It will be understood by referring to fig 1 p 167 where we have <br> an overlying granite A below this a bed of ordinary black micaceous <br> gneiss a a sending forth a small arm 6 very quartzy and losing <br> itself in the surrounding white coarse-grained crystalline limestone <br> d of which a thickness of about 8 feet is uncovered and is here <br> represented ; in this we find several blackish detached patches of <br> gneiss c <br> The line // crossing the lower part of the section represents <br> an apparent line of bedding very regular and showing itself the more <br> strongly from the foliation of a few inches on the upper side princi- <br> pally being much closer than throughout the rest of the mass This <br> line as shown in the section runs nearly E and W or at right <br> angles to the strike and inclines 20° from N to S The strike itself <br> is within a few degrees of N and S and inclines 15° to E <br> The portions of the limestone marked e in the section fig 1 are <br> foliated by crystals of blackish-green to light-green augite and white <br> scapolite ; in the part marked ff the foliation is produced by the <br> presence of laminae of mica Now when the lines of foliation are <br> examined which are well developed and distinct it will be seen that <br> these invariably run in one direction throughout the mass no matter <br> what minerals produce the foliation itself; also that this direction <br> coincides with the line of apparent bedding <br> Not many yards above and at right angles to this the section <br> represented in fig 5 was made showing as much as was uncovered <br> Fig 5 ” Section of granite gneiss and limestone at Jcegersborg <br> near Christiansand Norway <br> A Granite <br> a Granitic gneiss <br> b Ordinary gneiss <br> Foliated crystalline limestone <br> c <br> by soil or debris This presents a much-disturbed appearance ; the <br> central part appears to have been broken through by a fault and we <br> have on the east side on the surface granite A ; below this gneiss <br> « without grain passing into regular gneiss 6 and then the <br> limestone c c cut up by granite On the other side the granite is <br> absent ; and we have gneiss similar to the former and without grain <br> at top and then the limestone in which rounded masses of granite 35614745 110213 51125 Page 173 Text v 11 http //www biodiversitylibrary org/page/35614745 1855 Geological Society of London Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 11 1855 Geology Periodicals Smithsonian Libraries bhl page 35614745 dc identifier http //biodiversitylibrary org/page/35614745 smithsonian libraries Information field Flickr posted date ISOdate 2014-02-23 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12711590663 2015-08-26 21 00 03 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1855 Photos uploaded from Flickr by Fæ using a script | ||||
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