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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. Image File history File links Current_event_marker. ... Image File history File links This is a lossless scalable vector image. ... The Gay Head cliffs in Marthas Vineyard are made almost entirely of clay. ... A glacier is a large, persistent body of ice, formed largely of compacted layers of snow, that slowly deforms and flows in response to gravity. ... World map showing the location of Europe. ... Motto: (Out Of Many, One) (traditional) In God We Trust (1956 to date) Anthem: The Star-Spangled Banner Capital Washington D.C. Largest city New York City None at federal level (English de facto) Government Federal constitutional republic  - President George Walker Bush (R)  - Vice President Dick Cheney (R) Independence from... Glacial till with tufts of grass Till is an unsorted glacial sediment. ... Moraine at Mono Lake, California, United States Moraines clearly seen on a side glacier of the Gorner Glacier, Zermatt, Switzerland. ... Stratification gooberini went to lousville to dance on a praire and then he went down the hill to hang out with jarry. ... Patterns in the sand Sand is a granular material made up of fine rock particles. ... Gravel being unloaded from a barge Gravel is rock that is of a certain grain size range. ... Loam is soil composed of a relatively even mixture of three mineral particle size groups: sand, silt, and clay. ... The Triassic is a geologic period that extends from about 251 ± 0. ... The Carboniferous is a major division of the geologic timescale that extends from the end of the Devonian period, about 359. ... The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ... The Needles,situated on the Isle Of Wight, are part of the extensive Southern England Chalk Formation. ...

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. Limey shale overlaid by limestone. ... Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ... Close-up of granite from Yosemite National Park, valley of the Merced River Quarrying granite for the Mormon Temple, Utah Territory. ... Basalt Basalt (IPA: ) is a common gray to black volcanic rock. ... Gneiss Gneiss (IPA: ) is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally either igneous or sedimentary rocks. ... Scandinavia is a historical and geographical region centered on the Scandinavian Peninsula in Northern Europe and includes the three kingdoms of Denmark, Norway and Sweden. ...

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. Orders Allogromiida Carterinida Fusulinida - extinct Globigerinida Involutinida - extinct Lagenida Miliolida Robertinida Rotaliida Silicoloculinida Spirillinida Textulariida incertae sedis    Xenophyophorea    Reticulomyxa The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands that branch and merge to form a dynamic net. ... FOSSIL is a standard for allowing serial communication for telecommunications programs under DOS. FOSSIL is an acronym for Fido Opus Seadog Standard Interface Layer. ...

References

• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.