127 
16,780 acres. It is probable that various maps may have been 
consulted by those who made the estimation of the area pre- 
viously referred to, and this may have occasioned a disagree- 
ment between the various calculations. 
The coal seams, generally speaking, are conformable to 
one another, and to the iron-ore measures below them, and dip 
at variable angles from all points of the outcroppings. 
The iron-ore measures dip from the outcroppings on the 
Eastern side of the district at angles varying from 60°, 65°, 
and to 70° towards the centre of the basin, where the strata 
and coal seams are nearly horizontal for a considerable distance. 
_ The various beds are proved to be very regular in all the parts 
explored; we therefore know from experience the structure 
and constituents of the strata and minerals contained in them, 
even where no explorations by boring or pits have, as yet, been 
made. 
The angles of dip of the measures are much greater on 
the Eastern than they are on the Northern, Western, and 
South-Western portion of the district. The maximum dip will 
be found to exist from a point half a mile or so to the North 
of the Howbeach Valley, passing through Shakemantle and to 
Westbury Brook Iron Mine. 
There are, however, one or two other places on the 
Western side of the Forest where the dip is rather severe for 
limited distances. 
The coal measures to which we shall refer more particularly 
further on, the strata in which the coal is found, consists 
q principally of various beds of arenaceous and argillaceous sand- 
stone rock, shale, and indurated clay. The thickest part of 
the sandstone called Pennant rock is situated in the Lower 
Series, resting upon the Trenchard coal and its associated sand- 
stone shale and clay beds, all of which repose upon the Millstone 
Grit. 
The Millstone Grit, the upper part of which consists of 
the Farewell rock, as it is sometimes called, is composed of a 
variety of beds of sandstone, conglomerate, shale, indurate 
clay, and a species of yellow ochre or coloured earth of no value. 
