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See also:LONDON See also:CLAY , in See also:geology, the most important member of the See also:Lower See also:Eocene strata in the See also:south of See also:England. It is well See also:developed in the London See also:basin, though not frequently exposed, partly because it is to a See also:great extent covered by more See also:recent gravels and partly because it is not often worked on a large See also:scale. It is a stiff, tenacious, bluish clay that becomes See also:- BROWN
- BROWN, CHARLES BROCKDEN (1771-181o)
- BROWN, FORD MADOX (1821-1893)
- BROWN, FRANCIS (1849- )
- BROWN, GEORGE (1818-188o)
- BROWN, HENRY KIRKE (1814-1886)
- BROWN, JACOB (1775–1828)
- BROWN, JOHN (1715–1766)
- BROWN, JOHN (1722-1787)
- BROWN, JOHN (1735–1788)
- BROWN, JOHN (1784–1858)
- BROWN, JOHN (1800-1859)
- BROWN, JOHN (1810—1882)
- BROWN, JOHN GEORGE (1831— )
- BROWN, ROBERT (1773-1858)
- BROWN, SAMUEL MORISON (1817—1856)
- BROWN, SIR GEORGE (1790-1865)
- BROWN, SIR JOHN (1816-1896)
- BROWN, SIR WILLIAM, BART
- BROWN, THOMAS (1663-1704)
- BROWN, THOMAS (1778-1820)
- BROWN, THOMAS EDWARD (1830-1897)
- BROWN, WILLIAM LAURENCE (1755–1830)
brown on weathering, occasionally it becomes distinctly sandy, some-times glauconitic, especially towards the See also:top; large calcareous septarian concretions are See also:common, and have been used in the manufacture of See also:cement, being dug for this purpose at See also:Sheppey, near Southend, and at See also:Harwich, and dredged off the See also:Hampshire See also:coast. Nodular lumps of See also:pyrites and crystals of selenite are of frequent occurrence. The clay has been employed for making bricks, tiles and coarse pottery, but it is usually too tenacious for this purpose except in well-weathered or sandy portions. The See also:base of the clay is very regularly indicated by a few inches of rounded See also:flint pebbles with See also:green and yellowish See also:sand, parts of this layer being frequently cemented by carbonate of See also:lime. The See also:average thickness of the London Clay in the London basin is about 450 ft.; at See also:Windsor it is 400 ft. thick; beneath London it is rather thicker, while in the south of See also:Essex it is over 48o ft. In See also:Wiltshire it only reaches a few feet in thickness, while in See also:Berkshire it is some 50 or 6o ft. It is found in the Isle of See also:Wight, where it is 300 ft. thick at Whitecliff See also:Bay—here the beds are See also:vertical and even slightly reversed—and in See also:Alum Bay it is 220 ft. thick. In Hampshire it is sometimes known as the See also:Bognor Beds, and certain layers of calcareous See also:sandstone within the See also:clays are called See also:Barnes or Bognor See also:Rock. In the eastern See also:part of the London basin in See also:east See also:Kent the pebbly
the Oldhaven and See also:Blackheath Beds.
The London Clay is a marine See also:deposit, and its fossils indicate a moderately warm See also:climate, the See also:flora having a tropical aspect. Among the fossils may be mentioned Panopoea intermedia, Ditrupa Plana, Teredina personata, Conus concinnus, Rostellaria ampla, See also:Nautilus centralis, Belosepia, See also:foraminifera and diatoms. See also:Fish remains include Otodus obliquus, Sphyroenodus crassidens; birds are represented by Halcyornis Toliapicus, Lithornis and Odontopteryx, and See also:reptiles by Chelone gigas, and other turtles, Palaeophis, a See also:serpent and crocodiles. Hyracotherium leporinum, See also:Palaeotherium and a few other mammals are recorded. Plant remains in a pyritized See also:condition are found in great abundance and perfection on the See also:shore of Sheppey; numerous See also:species of palms, See also:- SCREW (O.E. scrue, from O. Fr. escroue, mod. ecrou; ultimate origin uncertain; the word, or a similar one, appears in Teutonic languages, cf. Ger. Schraube, Dan. skrue, but Skeat, following Diaz, finds the origin in Lat. scrobs, a ditch, hole, particularl
screw pines, See also:water lilies, cypresses, yews, leguminous See also:plants and many others occur; logs of coniferous See also:wood bored through by annelids and See also:Teredo are common, and fossil See also:resin has been found at See also:Highgate.
See EOCENE ; also W. See also:Whitaker, " The Geology of London and part of the See also:Thames Valley," Mem. Geol. Survey (1889)., and See also:Sheet See also:Memoirs of the Geol. Survey, London, Nos. 314, 315, 268, 329, 332, and Memoirs on the Geology of the Isle of Wight (1889).
End of Article: LONDON CLAY
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