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seams of coal have been worked extensively. For example, it 
has been proved that some of such seams of coal in Yorkshire 
had a thickness of from three to five feet. The Millstone Grit 
caps the hills of Yorkshire, and there is also evidence that 
coal has been worked in these measures from Silkstone to 
Chatsworth. 
The writer has had no opportunity to examine the coal 
measures at Wigpool, and cannot therefore determine what 
period it belongs to; but the section No. 15 of the Geological 
Survey produces some evidence. 
From the extreme Northern portion of the outcroppings of 
the Lower Limestone measures, the Millstone Grit measures 
have been completely denuded for a distance of 650 yards at 
least towards the South, but at that point it comes in as a thin 
edge of a wedge; attaining its maximum thickness further 
South, at the intersection of the Trenchard coal on Harrow 
Hill. The perpendicular thickness is about 480 feet, but near 
to Wigpool pit its thickness is no more than 120 feet. Re- 
storing, therefore, the coal measures to their proper position on 
the Government Section referred to, the Lower Trenchard seam 
would have occupied a position of 360 feet above the present 
surface line. This, therefore, seems to prove that the seam of — 
coal found at the Wigpool Pumping Pit exists in the lower part 
of the Millstone Grit series, and consequently must at one time 
have extended over the entire Forest. 
It should, however, be observed that the deduction thus 
arrived at depends entirely upon the accuracy of the Geological 
Survey Section referred to. Future observers may, however, 
be able to verify existing data and determine the question. 
In every mining district faults or dislocations, more or 
less extensive and troublesome, exist, but in the Dean Forest 
mineral field the known faults are of no very great extent, and 
the only effect has been to break up the continuity of the 
mineral deposited for limited distances. The most curious of 
these faults is that called the “ Horse,” first discovered in the 
Coleford Hill delf seam, on the Western side of the district. 
It seems to have first made its appearance below ground at a 
