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| Keywords: The Quarterly journal of the Geological Society of London (13935627262).jpg 1866 J FISHER WARP 555 <br> for my present purpose an advantage over calcareous strata in that <br> they are not soluble by water and the phenomena therefore are less <br> complicated As far as my observations extend I have found that <br> cylindrical pits and pipes are generally confined to soluble beds and <br> that the normal form of the cavities in clays sands and gravels is <br> that of troughs or furrows They are usually filled vsdth materials <br> derived from some neighbouring higher ground and consequently <br> generally differing from the subjacent stratum at that spot ; and it is <br> by the admixture of the contents of the furrows with the material of <br> the subjacent stratum that the warp which is derived from the two <br> conjointly comes to contain materials mixed in a different propor- <br> tion from that in the subjacent bed <br> These furrows must be important indications of the mode of de- <br> nudation of those surfaces where they occur ; nevertheless being <br> simply the tool-mark of the last agent which has moulded the sur- <br> face if we could determine from them what that was we need not <br> exclude other and different ones which may have preceded it <br> For the sake of a name I shall call the materials which fill these <br> furrows the trail And I will now give a few examples of them <br> in diagram <br> Fig 1 � Section of a furrow which crosses the Tendring Hundred <br> Railway near Great Bentley Church Essex <br> - � � � � � � � Eailway <br> It is 7 feet deep full of grey sandy and gravelly clay h eroded in brown sands <br> c The warp a covers it There is a layer of pebbles at the bottom of <br> the furrow and roots have penetrated throughout it The gravel is more <br> angular than that of the glacial drift from which it has been derived many of <br> the rounded pebbles having been broken up into angular fragments <br> At the gravel-pit Ballast Quay Farm near Wivenhoe Essex two <br> masses of trail have been left being too clayey for use They are <br> parallel to each other ; one of them is fifty yards long the other not <br> much less Erosion has gone on beneath them which is shown by <br> the pebbles of the warp and also of the trail lying in festoons <br> They are inclined at a small angle to the surface-drainage They <br> occur in sandy glacial gravel <br> For examples of these troughs see figs 1 and 5 London clay dug for <br> ballast at Bentley Tey near G-reat Bentley to the depth of 5 feet exposed a <br> section of a furrow ten yards long and a yard wide running in the direction of <br> the drainage of the surface 36165008 111477 51125 Page 555 Text v 22 http //www biodiversitylibrary org/page/36165008 1866 Geological Society of London Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 22 1866 Geology Periodicals Smithsonian Libraries bhl page 36165008 dc identifier http //biodiversitylibrary org/page/36165008 smithsonian libraries Information field Flickr posted date ISOdate 2014-04-21 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/13935627262 2015-08-26 06 50 24 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1866 Photos uploaded from Flickr by Fæ using a script | ||||
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