Brickearth: Difference between revisions

[[ File:Milford on Sea, Rook Cliff - geograph.org.uk - 1744521.jpg|thumb|200px|right|Brickearth deposits exposed as the topmost orange red layer in the cliff at Milford on Sea , Hampshire , UK]]

Brickearth is a piecesuperficial deposit of clayhomogeneous thats[[loam]] hard and jackie chan is asianor [[silt]]<ref name="kent">[https://shareweb.kent.gov.uk/Documents/Environment-and-planning/planning-and-land-use/kent-minerals-subject-plan-brickearth-extraction/kent-minerals-subject-plan-brickearth-1986.pdf Kent Minerals Subject Plan, BrickEathBrickEarth Written Statement], May 1986, Kent County Council Planning Department. Accessed April 2012</ref> deposited during the [[Pleistocene]] geological period.<ref name="chichester"/>

Brickearth typically occurs in discontinuous spreads, across southern England and South Wales , south of a line from Pembroke in the west to Essex in the east in depths of up to a metermetre.

Commercially useful deposits of about 2m to 4m thick are present in Kent, Hertfordshire and Hampshire, overlying [[chalk]], [[Thanet Beds]] or [[London Clay]]. The original deposition of the sediments occurred under cold climates where [[fluvial]] out-wash sediments from glaciers were subject to windy dry periods. The exposed finer-grained sediments were picked up and transported by the wind and were deposited wherever the wind strength decreased.<ref>[http://www.geo-east.org.uk/pp/essex/cgreport_pdf/GCA%201%20-%20Tendring%20Plateau.pdf Geodiversity Character Area Descriptions GCA 1 Tendring Plateau] {{Webarchive|url=https://web.archive.org/web/20160304072852/http://www.geo-east.org.uk/pp/essex/cgreport_pdf/GCA%201%20-%20Tendring%20Plateau.pdf |date=2016-03-04 }} Geo-East Partnership Accessed April 2012 </ref>

There are extensive brickearth deposits in [[Kent]], particularly on the [[North Downs]] dip slope and on the [[Hoo peninsula]], sections of the [[River Medway|Medway]] and [[River Stour, Kent|Stour]] valleys. TheIts mineral content is critical to its applicability in [[brickmaking]] and requires precise proportions of [[chalk]], [[clay]], and [[iron]].<ref name="NERC">[http://www.bgs.ac.uk/science/landUseAndDevelopment/engineering_geology/formation_engineering.html Loessic Brickearth Map] at Physical Properties and Behaviour of UK Rocks and Soils. British Geological Survey, National Environmental Research Council. Accessed April 2012</ref> Brickearth requires little or no admixture of other materials to render it suitable for the manufacture of '[[London stock brick|stock bricks]]'.<ref name="kent"/> In 1986, there were 4four active stock brick works were in Kent,: at [[Otterham Quay]], [[Funton]], [[Murston]] and [[Ospringe]].

The brickearth gives rise to rich and fertile soils which have been exploited for agriculture.<ref>[http://qra.org.uk/uploads/downloads/files/22/original/Tendring_Essex_Geodiversity_poster.pdf Tendring Essex Geodiversity poster] {{webarchive |url=https://web.archive.org/web/20130507120019/http://qra.org.uk/uploads/downloads/files/22/original/Tendring_Essex_Geodiversity_poster.pdf |date=May 7, 2013 }} Peter Allen, Gerald Lucy, Teresa O’Connor, David Bridgland, William George, Adrian Gascoyne, Adrian Knowles, Tom White. Quaternary Research Association, Geo Essex . Accessed April 2012</ref>

It is prone to rapid [[Slump (geology)|‘collapse’'collapse']] settlement when saturated with water and does not provide a firm foundation for buildings.<ref name="NERC"/>

In [[Chichester]], the brickearth is flintya flint-rich brown silty clay up to five metres thick, which occurs on the coastal plain. The brickearth is unfossiliferous but occasionally yields man-made flint implements.<ref name="chichester">[http://www.chichester.gov.uk/index.cfm?articleid=1827 Pleistocene] {{webarchive |url=https://web.archive.org/web/20071016150820/http://www.chichester.gov.uk/index.cfm?articleid=1827 |date=October 16, 2007 }} Chichester Museum website. Accessed April 2012</ref>

doi: 10.1144/​GSLGSL.QJEGH.1996.029.P2.04