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| Keywords: The Quarterly journal of the Geological Society of London (12684744794).jpg 276 PROCEEDINGS OF THE GEOLOGICAL SOCIETY May 19 <br> flints with irregular seams of eocene pebbles as shown in the an- <br> nexed diagram <br> Section near Portobello Inn between Farningham and Wrotham <br> N Scale 12 feet to 1 inch S <br> Talus Talus <br> a Dark ferruginous clay with flints c Seams of rounded Eocene pebbles <br> b b' Light-coloured sandy loam d Red and yellow ochraceous sand <br> e Clay sandy loam and Eocene pebbles in irregular alternations horizontally stratified ; <br> becoming obscure towards the south part of the section / Chalk <br> The materials which fill the cavities in the Portobello section and <br> form the subsoil in the cuttings on the Wrotham road have evidently <br> been derived from the wreck of some of the eocene tertiaries ; but if <br> it should be alleged that these cavities and the deposits which they <br> contain belong to the eocene period I would draw attention to the <br> following facts None of the eocene strata of this neighbourhood <br> which are in contact with the chalk are of the red and yellow colours <br> seen in the specimens now exhibited and obtained from this section <br> The lowest bed at Woolwich Bexley Erith Crayford and Dartford <br> is a whitish or greenish sand Above this is a pebble-bed The <br> sand generally rests on an even surface of chalk In the few cases <br> in which it fills cavities in the chalk the contents are very diiferent <br> from those of the Portobello section The sands are not only green- <br> ish but the flints have a dark green coating and the lining of the <br> pipes instead of being clay is of an indurated ochreous character <br> As a contrast to the contents of the Portobello cavities I exhibit <br> specimens from a pipe in a chalk-pit a little east of LulHngstone <br> Park These specimens agree with the characters of the matter fill- <br> ing pipes in the Hampshire basin where the chalk is there in con- <br> tact with the lower eocene bed The Portobello sands and clays on <br> the contrary have more of the aspect of those which form the mid- <br> dle portion of the vertical strata of Alum Bay and which Mr Prest- <br> wich has identified with the Bagshot sands <br> Moreover in the immediate vicinity of Portobello there is an <br> eocene outlier of white sand In a wood marked on the Ordnance <br> Map as Knock Mill but better known on the spot as Gravel-pit <br> Wood there is a bed of this sand exposed to the depth of about <br> 12 feet A reconstructed bed of eocene pebbles unmixed with an- <br> gular and subangular flints and imbedded in a ferruginous base of <br> sand and loam abuts abruptly against the western edge of the sand <br> as far as can be judged from the obscure state of the section disturbed <br> by the operations of digging gravel The contact of the sand with <br> the chalk is not exposed ; but the rock must be very near the bottom <br> of the pit The surface-soil for some distance through the wood is 35461330 109911 51125 Page 276 Text v 8 http //www biodiversitylibrary org/page/35461330 1852 Geological Society of London NameFound None NameConfirmed None EOLID 2913255 Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 8 1852 Geology Periodicals Smithsonian Libraries bhl page 35461330 dc identifier http //biodiversitylibrary org/page/35461330 smithsonian libraries Information field Flickr posted date ISOdate 2014-02-21 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12684744794 2015-08-27 12 53 15 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1852 Photos uploaded from Flickr by Fæ using a script | ||||
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