326 Reviews—The Geology of India. 
Coal.—During the past twenty years the production of Indian coal 
has risen from 1,397,818 tons in 1884 to 7,436,386 tons in 1908, the 
railways being the chief consumers; and this has reduced imported 
coal to an insignificant figure. Of the total output 95 per cent. was 
raised from the Gondwana coalfields of the Peninsula, the remainder 
being obtained from Tertiary beds in the extra-peninsular area. 
Bengal is the chief producer, and the most valuable of its coalfields 
are patches of Gondwana strata, faulted into the Archean schists and 
gneisses, and arranged as a band roughly east to west along the valley 
of the Damuda river. The Raniganj field, being nearest to Calcutta, 
still retains its pre-eminence and accounts for * of the total mined. 
Next to Raniganj in importance is the Jherria field, about 27 miles 
by 93 in extent. Workable coal occurs in the upper stage (Raniganj), 
but hitherto operations have been confined to the lower stage (Barakar), 
in which there are eighteen well-defined and mostly valuable seams, 
varying from 5 to 30 feet in thickness. As in the Raniganj field, 
a large amount of damage has been done to the coal by dykes and 
sheets of a peculiar igneous rock of the nature of a peridotite. Ten 
years ago this field was not worked, so that the results may be 
regarded as of good omen for the Indian coal-industry. The Tertiary 
coals of the outlying areas are of very little consequence, though much 
was expected at one time from a working on the Dandot plateau of the 
Salt Range, where, however, the collieries during the last two years 
have been worked at a loss. 
Gold.—This metal, as regards value, has long headed the list of 
‘minerals’ produced in India, though coal is fast catching it up, and 
there is very little doubt that ‘black diamond’ will be at the top of 
the tree in the course of the next few years. Gold is obtained in 
small quantities by washing in the river-gravels of various parts of 
India, but the bulk is mined from a rich reef on the Kolar field in the 
State of Mysore. The deepest workings, now somewhat more than 
3,000 feet below the surface, show little dimimution in the value 
or width of the auriferous quartz-vein. The Dharwar system of 
foliated schists, forming the ‘ country rock’ of the auriferous quartz 
in the Kolar field, is represented by bands of similar rocks folded into. 
the gneisses in various parts of the Peninsula, and many of these show 
traces of ancient workings, but recent operations other than those in 
Mysore have only yielded poor results. 
Lron-ores.—There seems to be a general consensus of opinion that. 
these are abundant and rich, especially in the Peninsula, but the 
native iron-smelting industry has been practically stamped out by 
cheap imported iron and steel within range of the railways. The most 
abundant iron-ores are the minerals magnetite and hematite, which 
occur in numerous places with quartz, making quartz iron-ore schists. 
which are generally members of the Dharwar and other Archean. 
schist series. The clay-ironstones of the Coal-measures, no doubt from. 
their proximity to fuel, are also beginning to attract attention. 
Other metals.—There has been a considerable quarrying of manganese- 
ore of late, so that India actually takes second place among the 
manganese-producing countries of the world. In the Nagpur area. 
the manganese-ore occurs as lenticular masses and bands in the 
