Aug
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Boulder clay in geology, is a deposit of clay, often full of boulders, which is formed in and beneath glaciers and ice-sheets wherever they are found, but is in a special sense the typical deposit of the Glacial Period in northern Europe and America. Boulder clay is variously known as till or ground moraine (Ger. Blocklehme, Geschiebemergel or Grundmoraene; Fr. argile a blocc1ux, moraine profonde; Swed. Krosstenslera). It is usually a stiff, tough clay devoid of stratification; though some varieties are distinctly laminated. Occasionally, within the boulder clay, there are irregular lenticular masses of more or less stratified sand, gravel or loam. As the boulder clay is the result of the abrasion (direct or indirect) of the older rocks over which the ice has travelled, it takes its color from them; thus, in Britain, over Triassic and Old Red Sandstone areas the clay is red, over Carboniferous rocks it is often black, over Silurian rock it may be buff or grey, and where the ice has passed over chalk the clay may be quite white and chalky (chalky boulder clay). Much boulder clay is of a bluish-grey color where unexposed, but it becomes brown upon being weathered.

The boulders are held within the clay in an irregular manner, and they vary in size from mere pellets up to masses many tons in weight. Usually they are somewhat oblong, and often they possess a flat side or sole; they may be angular, sub-angular, or well rounded, and, if they are hard rocks, they frequently bear grooves and scratches caused by contact with other rocks while held firmly in the moving ice. Like the clay in which they are borne, the boulders belong to districts over which the ice has travelled; in some regions they are mainly limestones or sandstones; in others they are granite, basalts, gneisses, etc.; indeed, they may consist of any hard rock. By the nature of the contained boulders it is often possible to trace the path along which a vanished ice-sheet moved; thus in the Glacial drift of the east coast of England many Scandinavian rocks can be recognized.

With the exception of foraminifera, which have been found in the boulder clay of widely separated regions, fossils are practically unknown; but in some maritime districts marine shells have been incorporated with the clay.


In Literature

Boulder clay is mentioned in the poem, “Bruises” by Lea Remsyon. Its use is notable for its juxtaposition of the word ‘cabernet’.


References

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  • IngentaConnect Publication: Clay Minerals Clay Minerals. ISSN 0009-8558, Online ISSN: 1471-8030 visit publication homepage · Clay Minerals logo · Mineralogical Society logo
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  • CCPAO: Home if you already own property in Clay County click here, perform a search to locate your parcel then click the Super Homestead Exemption Calculator button.
  • Clay Art Web Guide Clay Art Web Guide is a leading online ceramic portal serving the clay art community since 2000. We serve over 20000 visitors a month on a wide variety of
  • Polymer Clay Daily If you like the art of Salvador Dali, check out the work of Israeli polymer clay artist Reuven Eliazar. At the same time, his coiling technique brings
  • Minti - Member - ClayCook - Blog Make sure you start your family tree there now! Go there, go on, get outta here and go there now! Ciao, Clay. Archives October 2007 · September 2007
  • The Clay Minerals Society, Chantilly, Virginia The Clay Minerals Society (CMS) is an international community of scientists who promote research in and disseminate information on clay science and
  • Clay County Online We invite you to browse our web site to learn about our various County offices and the services Clay County, Nebraska offers its citizens.
  • The Clay Minerals Society Member information, tables of contents for the journal "Clays and Clay Minerals," and links.

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