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Near to Shakemantle Pumping Pit, on the Eastern side of 
the Forest, a portion of the Trenchard measures are exposed in 
a section of the railway cutting, and the thickness of the Mill- 
stone Grit in this neighbourhood, taken to the top of the 
Carboniferous Limestone, is 780 feet; this railway cutting 
exhibits a beautiful section of the upper beds of this formation. 
In the upper portion of the series beds of a very pure fireclay 
exist, and have been worked at some points. Similar beds also 
exist above the Trenchard seam of coal, and have been exploited 
for the manufacture of bricks at the Southern extremity of 
Ruspidge Meend and to the West of Shakemantle Pumping 
Pit, as also at Darkhill and Milkwall Meend. The same belt of 
clay is visible between the upper and lower Oakwood Mine 
levels on the South-Eastern side of the Forest. 
At a point in the Millstone Grit, towards the South-East 
from Lambsquay House, and North-East from Gattles Cross, 
there exists fine beds of pure limestone which have been 
used for lime for many years. A bluish thin bed of lime- 
stone has also been worked at Oldcroft, near Soilwell House, 
but whether this is the remains of the Millstone Grit has not 
been ascertained. A sufficient number of sections do not exist 
by which it could be proved whether these limestone beds are 
general, 7.e., continuous in the Millstone Grit. 
At a considerable distance to the South-West of Shake- 
mantle Iron Mine, the Millstone Grit commences to thin out 
towards the Howbeach Valley, where there is no appearance of 
it, but the Pennant rock seems to rest upon the limestone. 
The Carboniferous Limestone succeeds the Millstone Grit 
_ in a descending order, and the junction of the two series is 
distinctly marked by shale and a bed of limestone of from 
eight to twelve feet thick, of a tine texture, and slightly red in 
colour. This rock is the upper portion of the upper Carboni- 
ferous Limestone, and is locally known as the “ Lid-stone,” 
because it forms a cover to the iron-ore deposits, in fact, iron- 
ore is never found above it unless this rock had suffered 
fracture, and so formed an open joint into which ore may have 
intruded itself. Immediately below this bed of rock, a thick 
