16 
BALL AND SIMPSON: COALFIELDS OF INDIA. 
north-east, and for a hundred miles south-west, being exposed 
only along the northern front of the Patkai range. They are con- 
sidered to be of Tertiary, probably miocene age, and to exceed 
2,000 feet in thickness. The most remote coal-bearing rocks that 
have been noted in these hills are on the flanks of Maiobum in 
the Dihing valley, where LaTouche ^ found two seams of hard, 
bright coal, the one of which is 3 feet in thickness and dips 20° 
to S. E., whilst the other has a thickness exceeding 6 feet. In the 
overlying sandstones of Upper Tertiary age lenticular bands of im- 
pure lignite, up to three feet in thickness, were found. This latter 
is the coal mentioned by Wilcox ^ in his account of the expedi- 
tion to the Irrawadi in 1828. Another outlying patch of the coal 
measures was discovered by Maclaren in the Manabum Range, a 
long spur parallel with the Noa Dihing river. A Hmited examination 
did not reveal the presence of coal-seams. Passing south again to 
the principal range the same rocks occur in the Namrup, and in 
the Namchik. Between the Namchik and the Tirap there appears 
to be a gap, due no doubt to the embaying of the range and the 
consequent denudation of the coal measures to the plains' level. 
From the Tirap to the Namsang river, a distance of 20 miles, the 
measures appear to be continuous, and it is in this locality that 
they appear to have attained their maximum development and that 
the extensive mines of the Assam Railways and Trading Company 
are situated. In the Namsang the great reversed fault which runs 
along the base of the hills has either raised the seam sufficiently 
high to enable the Namsang stream to erode it completely or it hes 
hidden beneath the alluvium. A second reversed fault to the north- 
west has raised and exposed the coal measures along the north- 
western flank of the Tipam hills, from whence they strike east of 
Jaipur to a little beyond the Disang river. They are again brought 
to the surface by the same or similar faults in the hills south of 
Nazira and of Moriani. 
Namchik river. — In 1911 Messrs. G. C. Webster and E. H. Pascoe ^ 
made a detailed examination of the coal in the Namchik valley. 
The seams were found in a small tributary on the right bank of 
the river. Sixty feet of coal were measured within a thickness of 
360 feet of strata. The best seam measures 26 feet and contains 
» Rec, O. S. I., XIX, p. 112 (1884-1885). 
As. Res., XVII, pp. 322, etc. (1828). 
» Rec, 0. 8. I., XLI, pt. .3, pp. 214-210 (1911). 
