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| Keywords: The Quarterly journal of the Geological Society of London (12645856563).jpg 194 <br> PROCEEDINGS OF THE GEOLOGICAL SOCIETY <br> slates at Comrie and proving that it too is cleavage and not stratifi- <br> cation The position of the other planes is less definite from their <br> curvature but they seem on the whole to dip S E and the large <br> rock-masses in some of the neighbouring hills appear also to dip <br> in that direction The subjoined figure fig 7 may give some <br> imperfect idea of the contortions in the beds in one part of these <br> quarries The borders represented as seen in the quarry are nearly <br> in the line of cleavage <br> Fig 7 ” Contortions in Slate Aberuchil Quarry <br> On the whole therefore I conclude that the chief division -planes <br> seen in the slates near Comrie are those of cleavage and not of <br> deposition The dip of this cleavage is predominantly N 10° W <br> and the direction W 10° S to E 10° N and thus oblique to the <br> general course of the slate on the south flank of the Grampians <br> The strike of the beds as marked by the other division-planes <br> N 30° W with a S W or more rarely N E dip is still less conform- <br> able to the usual course of the slates This deviation may perhaps <br> be caused by the intrusion of the Glen Lednock syenite though as <br> stated it appears to have exercised no very marked influence on the <br> position of the slates <br> 12 Mica-slate of Loch Earn ” The relation of the clay-slate to the <br> mica-slate formation is not very clearly shown in any of the sections <br> I examined in Strath Earn Mica-slate appears near St Eillans <br> Church but soon again gives place higher in the valley to clay- <br> slate and greywacke This mica- slate as already noted besides a <br> very distinct foliation much twisted and contorted as is common <br> in mica-slate shows also other division-planes parallel to the bed- <br> ding of the clay-slates Mica-slate predominates along the north <br> bank of Loch Earn but the rocks are much concealed by wood and <br> vegetation and the strata greatly disturbed probably by intrusive <br> greenstones So irregular are the beds that at first it seems almost <br> impossible to discover any dominant dip or direction On further <br> examination however the direction E 22° IN comes out as the <br> average result of the whole; or excluding a few dips nearly at <br> right angles to the others a mean direction of E 40° N with a <br> The strike of these beds is thus parallel to that of the gneiss on the N W <br> coast of Ross and Sutherland which it has been supposed to characterize as an <br> older group ; but see my paper Quart Journ Geol Soc vol xvii p 110 35328155 109632 51125 Page 194 Text v 19 http //www biodiversitylibrary org/page/35328155 1863 Geological Society of London Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 19 1863 Geology Periodicals Smithsonian Libraries bhl page 35328155 dc identifier http //biodiversitylibrary org/page/35328155 smithsonian libraries Information field Flickr posted date ISOdate 2014-02-20 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12645856563 2015-08-27 12 00 45 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1863 Photos uploaded from Flickr by Fæ using a script | ||||
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