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| Keywords: The Quarterly journal of the Geological Society of London (12645214255).jpg 1849 <br> BROWN ON ERECT SIGILLARI <br> 359 <br> stratum in the ascending order forms the roof of the coal In such <br> cases the surface of the peat bog could not have been level when the <br> shale was deposited upon it some small patches having been still <br> above water ; and as no upright trees are found in the sandstone <br> roof it may reasonably be inferred that plants would not vegetate <br> upon the bog itself a layer of soft mud being necessary in the first <br> instance for germinating the seeds ; but when a plant had once taken <br> root in this mud its rootlets penetrated downwards into the peat <br> and furnished an abundant supply of nutriment for the rapid growth <br> of the tree from the rich mass of decaying vegetable matter beneath <br> I may here observe that the quality of the upper part of the seam <br> appears invariably to be influenced by the nature of the roof the coal <br> being highly charged with iron pyrites under a sandstone but quite <br> free from it under a shale roof And since no upright trees are <br> found in the sandstone roofs is it probable that the luxuriant forest <br> of Sigillariae growing in the mud above the peat bog has taken up <br> the sulphuret of iron and thus produced such a beneficial eifect upon <br> the quality of the coal Both sulphuric acid and the oxide of iron <br> are inorganic constituents of plants and it has been ascertained that <br> natural and artificial waters that have a sulphureous taste when em- <br> ployed in irrigating meadows give birth to a very luxuriant vegeta- <br> tion f but whether the growth of a forest of Sigillarise upon the sur- <br> face of the peat bog is an adequate explanation of the absence of iron <br> pyrites from the upper part of the coal seam I must leave to more <br> skilful botanists to determine <br> Having shown that Sigillaria alternans was provided with roots <br> peculiarly adapted for flourishing upon a soft muddy soil and thus <br> furnished additional proof that coal seams have been formed from <br> beds of peat or other decaying vegetable matter accumulated on the <br> surface it only remains for me now to direct attention to the fossil <br> represented in fig 9 which it will be observed in its external aspect <br> Fig 9 <br> Stump broken off close to the root one-tivelfth of natural size <br> Mr Buddie states in the Trans of the Nat Hist Society of Newcastle vol i <br> p 217 that the coal seams in Northumberland are always more or less intermixed <br> with iron pyrites under a sandstone roof <br> t Johnston's Agricultural Chemistry p 273 35269009 109512 51125 Page 359 Text v 5 http //www biodiversitylibrary org/page/35269009 1849 Geological Society of London NameFound Sigillaria alternans Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 5 1849 Geology Periodicals Smithsonian Libraries bhl page 35269009 dc identifier http //biodiversitylibrary org/page/35269009 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 N02/12645214255 2015-08-27 10 52 35 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1849 Photos uploaded from Flickr by Fæ using a script | ||||
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