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| this may account for the difference. The Carboniferous Lime- 
stone may be traced as a continuous belt round the Forest of 
Dean, from the Howbeach Valley to Wigpool on the North, 
| North-Western, Western, and South-Western outcroppings to 
Lydney Park, and is continuous half-way between the Red 
Hill and the Leech Pool. 
14 From this neighbourhood, and along the South-Eastern 
croppings of the coal field to Howbeach Valley, the limestone 
is absent. 
. The lower coal measures overlap and repose upon the older 
_ rocks. Near Soilwell Farm, the Trenchard outcroppings are 
- found nearly in contact with the Old Red Sandstone. 
i Buckland and Conybere, in a paper entitled “‘ Observations 
on the South-Western Coal District of England,” published in 
the Transactions of the Geological Society in 1824, considered 
| that the absence of the limestone is due to a fault, but they do 
not explain how it was brought about. Maclauchan, in his 
_ paper published in 18338, took the same view, which appears to 
have been derived from the late Mr David Mushet. 
It is very likely that the strata of the limestone along the 
line of the country mentioned was much dislocated in past 
Geological periods, and it is possible that a fault may also exist, 
but the entire absence of the limestone is more particularly 
due to the influences exerted throughout a very long period by 
denudation. 
| : How far in perpendicular depth the limestone has been 
| removed is a matter of conjecture at present. 
Mr Maclauchlan’s section shows it at a depth of over 300 
_ yards below the surface, but whether he had sufficient reason 
for such an hypothesis is doubtful. At whatever level denuding 
influences ceased, there we may expect to find the limestone, 
and it is possible that the difference of level between the lowest 
point in the Old Red Sandstone, South of Lydney, as it existed 
at that time, and its outcroppings along the neighbourhood 
referred to, may give some clue to the probable depth. 
_ Probably the limestone was thinned out from the Howbeach 
Valley along the ancient site now known as Cockshoot 
