par has a milky shimmer like
moonshine, the hypersthene has a bronzy metalloidal gleam. Very often
the different rock types occur in close association as one set forms
bands alternating with another set, or veins traversing it, and where
one facies appears the others also usually are found. The 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 parent magma. The banded structure which
these rocks commonly present in the field is only in a small measure due
to crushing, but is to a large extent original, and has been produced by
fluxion in a viscous crystallizing intrusive magma, together with
differentiation or segregation of the mass into bands of different
chemical and mineralogical composition. There have also been, of course,
earth movements acting on the solid rock at a later time and injection
of dikes both parallel to and across the primary foliation. In fact, the
history of the structures of the charnockite series is the history of
the most primitive gneisses in all parts of the world, for which we
cannot pretend to have as yet any thoroughly satisfactory explanations
to offer. A striking fact is the very wide distribution of rocks of this
group in the southern hemisphere; but they also, or rocks very similar
to them, occur in Norway, France, Germany, Scotland and North America,
though in these countries they have been mostly described as pyroxene
granulites, pyroxene gneisses, anorthosites, &c. They are usually
regarded as being of Archean age (pre-Cambrian), and in most cases this
can be definitely proved, though not in all. It is astonishing to find
that in spite of their great age their minerals are often in excellent
preservation. In India they form the Nilgiri Hills, the Shevaroys and
part of the Western Ghats, extending southward to Cape Comorin and
reappearing in Ceylon. Although they are certainly for the most part
igneous gneisses (or orthogneisses), rocks occur along with them, such
as marbles, scapolite limestones, and corundum rocks, which were
probably of sedimentary origin. (J. S. F.)

CHARNWOOD FOREST, an upland tract in the N.-W. of Leicestershire,
England. It is undulating, rocky, picturesque, and in great part barren,
though there are some extensive tracts of woodland; its elevation is
generally 600 ft. and upwards, the area exceeding this height being
about 6100 acres.