DE'rAlFilOl) DIOSORIPTIONS OK THE RESPECTIVE COALFIELDS. Kk 
from this cause broke out at two well-known collieries. Smaller 
fires have also been experienced at other mines. 
The great thickness of some of the best coal seams adds consider- 
ably to the difficult)^ of working for not only does it militate against 
a high percentage of extraction, but it also introduces serious 
danger from falls of coal from the lofty pillars formed in the cus- 
tomary method of working. At a number of mines this difficulty 
is being successfully met by a system of working in stages with 
an unworked layer of coal between the successive stages. At one 
mine where a seam 100 feet thick dips at an angle of 45° a system 
of working in horizontal slices has been introduced and promises 
to be a success. 
By the extension of the East Indian Railway Company's Barakar 
branch this coalfield first obtained railway connection in 1894, in which 
year 15,000 tons of coal were produced. In 1903 the Bengal-Nagpur 
Railway Company extended their lines into the field, and the two 
railway companies will eventually take each about equal portions 
of the coal traffic. In 1910, 193 coUieries were at work and the 
output was 5,794,534 tons of coal or about one half of the whole 
production of India. The expansion during the decade 1899-1908 
was almost ninefold, and in 1906 the production outstripped that 
of the neighbouring Raniganj field, and the Jharia field assumed 
the lead and became the largest producer of coal in the Indian 
Empire. 
Bokaro. — The Bokaro coalfield lies some two or three miles 
west of the termination of the Jharia field. Its greatest length 
is in an east and west direction and is about 40 miles ; its maximum 
breadth from north to south does not exceed 6 J miles. The total 
area is 220 sq. miles. 
The rocks represented range from Talchirs to upper Pancheti? 
and are much disturbed by faulting ; high dips being the rule 
rather than the exception. Although coal-seams are found in the 
Raniganj beds, yet the whole of the workable coal occurs in the 
Barakars. In the opinion of Mr. Hughes^ who mapped the area 
in 1866 the coal cannot be compared in its general quality with 
that obtained from the Jharia coalfield. The number of coal-seams 
is very large and some of them are enormously thick. In many 
places they have been much damaged by intrusions of trap. 
» Alem., G. S. I., Vol. VI, p. 58 (1867). 
