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| Keywords: The Quarterly journal of the Geological Society of London (12512474604).jpg ARGYLL INVERARY DISTRICT 363 <br> as to the possible cause of such an association of these two rocks <br> there is one preUminary question which must be either settled by <br> proof or passed over as not really admitting of any serious doubt ; <br> I mean the question of the sedimentary origin of the mica-slates On <br> this point I can only say that there appears to me to be every proof <br> except one ” the remains of organic life Nothing can be more com- <br> plete and regular than the stratification of these rocks ; and if there <br> be any other mode whereby such a mechanical arrangement of earthy <br> matter can be effected than that of aqueous deposition it is a mode <br> of which we have no knowledge There are the same alternations <br> Fig 2 ” Ideal Section of the Inverary District <br> Mica-slate <br> which prevail in all other sedimentary rocks of siliceous shaly and <br> calcareous beds ; and in respect to the latter I have had the benefit <br> of examining some limestone strata in this district along with Sir <br> Roderick Murchison which were pronounced by him to be not very <br> much more crystalline than some of the limestones of the older rock's <br> which are so abundant in their oceanic fossils <br> The absence of organic remains however is of course no real <br> stumbling-block in the way of our conclusion as it is perfectly con- <br> sistent with our knowledge of actual facts that such remains if they <br> ever existed may well have been obliterated by metamorphic action ; <br> and further because it is equally consistent with theories having at <br> least some probability that in these very ancient rocks we should find <br> evidences of a period anterior to the introduction of organized beings <br> to our planet <br> Taking for granted then the sedimentary origin of the mica-slates <br> and therefore the comparative horizontality of their first position it <br> becomes a question of much geological interest how they came to <br> assume such a highly inclined position and how such masses of in- <br> trusive igneous rock came to be interposed between their beds with- <br> out interrupting their general conform ability of dip and of direction ; <br> the igneous and the aqueous rocks assuming the position as it were <br> of contemporaneous formations <br> With igneous rocks of another class this is no unknown phseno- <br> menon ; sheets of trap or lava interposed between the beds of sediment- <br> ary rocks are not unfrequent ; and a remarkable example has been <br> brought under the notice of this Society by Professor E Forbes in <br> reference to the oolites of Skye But the cause of such a conjunction 34983498 108767 51125 Page 363 Text v 9 http //www biodiversitylibrary org/page/34983498 1853 Geological Society of London Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 9 1853 Geology Periodicals Smithsonian Libraries bhl page 34983498 dc identifier http //biodiversitylibrary org/page/34983498 smithsonian libraries Information field Flickr posted date ISOdate 2014-02-14 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12512474604 2015-08-27 10 00 06 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1853 Photos uploaded from Flickr by Fæ using a script | ||||
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