153 
The Starkey coal also exists in a similar condition. It is 
not very clear what portion of the Forest is represented by 
this section, but it is highly probable that it has been made of 
portions of the measures from different localities, because the 
seams of coal referred to are not found in exactly the same 
form at the Lightmoor and some other collieries. It is very 
evident that the seams of coal were deposited at various periods, 
otherwise the intervening veins of shale could not exist. It is 
also clear that consequent upon denuding action the thinning- 
out effects of the same beds of rock have been variable, in fact 
they are formed as already indicated from a mere line in some 
places to 86ft. in others. It is difficult to form a correct 
opinion of the entire effects produced by denudation upon all 
the other intervening beds of rock and coal seams in all parts 
of the Forest; but if we assume that its influence lessened 
upwards from the Upper Churchway seams, then we should be 
obliged to conclude that the interval of time which elapsed, and 
represented by the thin beds of coal between the upper beds of 
rock, must have been too short to permit of the growth and 
decay of a sufficient amount of vegetable matter to produce 
thicker seams of coal. 
On the contrary, it could be urged that the beds of rock, 
shale, and coal seams may originally have had any other thick- 
ness, and that a series of reductions or thinning-out may have 
taken place. The first assumption, however, is most probable, 
but in either case the question is as interesting as it is im- 
portant, and the co-relation of the coal beds of the Forest of 
Dean with those in the surrounding coal fields of Bristol and 
Wales, is rendered all the more difficult, because we cannot 
suppose that vegetable growth has been subjected to any 
_. particular variation in places so closely situated. 
There are more workable seams of coal in the South Wales 
coal fields than there are in the Bristol or in the Dean Forest 
district, and that fact alone ought to be sufficient evidence 
that similar conditions of coal beds once existed over the entire 
~ area of Gloucestershire, and their absence can only be accounted 
_ for, as we have previously indicated, on Geological grounds. 
E 
