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| Keywords: The Quarterly journal of the Geological Society of London (12981479134).jpg 1859 <br> SCKOPE COliTES AND CRATEKS <br> 517 <br> and the terminal cone of Etna to be eruptive cones But on the <br> other hand M de Buch in the passage I have already referred to <br> affirms the extreme regularity of the entire figure of Etna to be a <br> proof that it could not be the product of eruptions but must have <br> been upheaved at a single stroke ' a V instant meme de sanaissancef ' <br> In fact M de Buch's test is the precise reverse of M de Beaumont's <br> Suppose however we take M de Beaumont's as that of the latest <br> authority on the point Surely it is trifling with the subject to rest <br> so important a distinction as to origin upon a difference in outline <br> so slight so disputable nay so necessarily variable under varying <br> circumstances of composition dilapidation c independently of all <br> question of origin In the first place too it is undeniable that <br> many perhaps the majority of the acknowledged cones of eruption <br> about Etna and in Central France show a sloping outline by no <br> means ' rectilinear but sweeping downwards in a gradual curve <br> that lessens in steepness till it meets the base which is M de Beau- <br> mont's characteristic of an upheaved cone In the second place <br> the slightest consideration makes it obvious that great differences in <br> this respect must be occasioned by casual differences in the size <br> shape or mineral character of the ejected fragments by their more <br> or less heated state and consequent coherence or non- coherence at <br> the time of their fall and accumulation by their greater or less degra- <br> dation by storms of rain accompanying the eruption or by a longer <br> or shorter subsequent exposure to atmospheric influences In the <br> case of the larger volcanic mountains if we suppose them the pro- <br> duct of repeated eruptions a graduated slope towards the base must <br> necessarily have been occasioned not only by longer exposure to the <br> agents of degradation but still more by the accumulation of the <br> lavas and scorioe emitted from lateral vents on the lower flanks of <br> the mountain Indeed M de Beaumont by admitting the many <br> Fig 5 Outline of Etna as seen from near Catania From Mem <br> Soc Geol de France vol iv pi 2 <br> hundred parasitic cones of Etna and their lava-streams to be eruptive <br> himself accounts on the theory of accumulation not of upheaval for <br> the graduated slope of the mountain as a whole into the plain <br> around And in truth the visible portion of his central up- <br> Memoires iv p 157 <br> t Canaries p 326-7 36162084 111474 51125 Page 517 Text v 15 http //www biodiversitylibrary org/page/36162084 1859 Geological Society of London Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 15 1859 Geology Periodicals Smithsonian Libraries bhl page 36162084 dc identifier http //biodiversitylibrary org/page/36162084 smithsonian libraries Information field Flickr posted date ISOdate 2014-03-07 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12981479134 2015-08-26 14 57 02 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1859 Photos uploaded from Flickr by FĂŚ using a script | ||||
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