CHARNOCKITE
, a See also:series of foliated igneous rocks of wide See also:distribution and See also:great importance in See also:India, See also:Ceylon, See also:Madagascar and See also:Africa
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The name was given by Dr T
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H
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See also:- HOLLAND
- HOLLAND, CHARLES (1733–1769)
- HOLLAND, COUNTY AND PROVINCE OF
- HOLLAND, HENRY FOX, 1ST BARON (1705–1774)
- HOLLAND, HENRY RICH, 1ST EARL OF (1S9o-,649)
- HOLLAND, HENRY RICHARD VASSALL FOX, 3RD
- HOLLAND, JOSIAH GILBERT (1819-1881)
- HOLLAND, PHILEMON (1552-1637)
- HOLLAND, RICHARD, or RICHARD DE HOLANDE (fl. 1450)
- HOLLAND, SIR HENRY, BART
Holland from the fact that the tombstone of See also:Job See also:Charnock, the founder of See also:Calcutta, is made of a See also:block of this See also:rock
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The charnockite series includes rocks of many different types, some being See also:acid and See also:rich in See also:quartz and See also:microcline, others basic and full of See also:pyroxene and See also:olivine, while there are also intermediate varieties corresponding mineralogically to norites, quartz-norites and diorites
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A See also:special feature, recurring in many members of the See also:group, is the presence of strongly pleochroic, reddish or See also:green See also:hypersthene
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Many of the minerals of these rocks are " schillerized," as they contain See also:minute platy or See also:rod-shaped enclosures, disposed parallel to certain crystallographic planes or axes
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The reflection of See also:light from the surfaces of these enclosures gives the minerals often a See also:peculiar See also:appearance, e.g. the quartz is See also:blue and opalescent, the See also:felspar has a milky shimmer like moonshine, the hypersthene has a bronzy metalloidal gleam
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Very often the different rock types occur in See also:close association as one set forms bands alternating with another set,or See also:veins traversing it, and where one facies appears the others also usually are found
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The See also:term charnockite consequently is not the name of a rock, but of an assemblage of rock types, connected in their origin because arising by differentiation of the same See also:parent magma
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The banded structure which these rocks commonly See also:present in the See also:- FIELD (a word common to many West German languages, cf. Ger. Feld, Dutch veld, possibly cognate with O.E. f olde, the earth, and ultimately with root of the Gr. irAaror, broad)
- FIELD, CYRUS WEST (1819-1892)
- FIELD, DAVID DUDLEY (18o5-1894)
- FIELD, EUGENE (1850-1895)
- FIELD, FREDERICK (18o1—1885)
- FIELD, HENRY MARTYN (1822-1907)
- FIELD, JOHN (1782—1837)
- FIELD, MARSHALL (183 1906)
- FIELD, NATHAN (1587—1633)
- FIELD, STEPHEN JOHNSON (1816-1899)
- FIELD, WILLIAM VENTRIS FIELD, BARON (1813-1907)
field is only in a small measure due to crushing, but is to a large extent See also:original,and has been produced by fluxion in a viscous crystallizing intrusive magma, together with differentiation or segregation of the See also:mass into bands of different chemical and mineralogical See also:composition
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There have also been, of course, See also:earth movements acting on the solid rock at a later See also:- TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
- TIME, MEASUREMENT OF
- TIME, STANDARD
time and injection of dikes both parallel to and across the See also:primary foliation
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In fact, the See also:history of the structures of the charnockite series is the history of the most See also:primitive gneisses in all parts of the See also:world, for which we cannot pretend to have as yet any thoroughly satisfactory explanations to offer
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A striking fact is the very wide distribution of rocks of this group
in the See also:southern hemisphere; but they also, or rocks very similar to them, occur in See also:Norway, See also:France, See also:Germany, See also:Scotland and See also:North See also:America, though in these countries they have been mostly described as pyroxene granulites, pyroxene gneisses, anorthosites, &c
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They are usually regarded as being of Archean See also:age (pre-See also:Cambrian), and in most cases this can be definitely proved, though not in all
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It is astonishing to find that in spite of their great age their minerals are often in excellent preservation
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In India they See also:form the Nilgiri Hills, the Shevaroys and See also:part of the Western See also:Ghats, extending southward to Cape See also:Comorin and re-appearing in Ceylon
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Although they are certainly for the most part igneous gneisses (or orthogneisses), rocks occur along with them, such as See also:marbles, See also:scapolite limestones, and See also:corundum rocks, which were probably of sedimentary origin
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