Keywords: The Quarterly journal of the Geological Society of London (12961495654).jpg TYLOR QUATEENARY aRAVELS <br> 87 <br> is exposed at 45 feet above the Ordnance datum-line I have found <br> the Cyrena at about the same height at D ; and this is the highest <br> level at which the Cyrena is found either in the Thames valley or in <br> the Humber or Somme <br> Pig 18 is a section exhibiting the excavation of the chalk and <br> Thanet sands by the old Eiver Thames The chalk a reaches a <br> height fig 18 of about 45 feet above the Ordnance datum-line; and <br> the Thanet sands 6 have been partly denuded so that only 15 feet <br> out of 60 feet seen in the Station baUast-pit at Erith remain here <br> The gravel c reposes conformably on the top of the Thanet sands at <br> G the upper part of the section ; but the gravel follows the denuded <br> surface of the chalk filling up the concavities It contains much <br> rearranged Thanet sand ; and a large lump 5 is conspicuous in it <br> The 6 -feet step in the chalk is well marked and sharply cut out by <br> the action of the river flowing at right angles to the line G K <br> Fig 19 is a section in the same direction as fig 18 ; but steps from <br> Fig 19 ” Section in Erith Pit l atural scale <br> 1 to 2 feet deep cut by water in the Thanet sands are distinctly <br> seen The gravel is then deposited in the concavities formed by <br> the water Brick-earth with veins of gravel d follows on for <br> 15 feet and the covering gravel e succeeds sloping to the river at <br> a gradient of 1 in 200 only The Thanet sand is a somewhat inco- <br> herent mass ; and the action of the water must have been very gentle <br> to have formed such perfect steps The deposition of gravel and <br> brick-earth must have at once followed the denudation <br> Fig 20 is a section along part of the line G E The chalk with <br> a basement-bed of Thanet sands and green-coated flints is seen at d <br> in situ The Thanet sands in fig 20 were excavated by one of the <br> side-streams which formerly flowed into the ancient Thames The <br> edges of the sand 6 are so sharply cut in this transverse section <br> of a river-bed that it would be difficult to believe it was not an ar- 36102932 111288 51125 Page 87 Text v 25 http //www biodiversitylibrary org/page/36102932 1869 Geological Society of London NameFound Cyrena NameConfirmed Cyrena EOLID 4757476 NameBankID 4134596 Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 25 1869 Geology Periodicals Smithsonian Libraries bhl page 36102932 dc identifier http //biodiversitylibrary org/page/36102932 smithsonian libraries Information field Flickr posted date ISOdate 2014-03-06 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12961495654 2015-08-26 15 54 56 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1869 Photos uploaded from Flickr by Fæ using a script |