IRONSTONE FORMATION OF THE FOREST OF DEAN. 
225 
near Blakcncy Hill, a little to the east of Staple Edge enclosure ; it 
rc-appcars at Red Hill, near Sydney. The effect of this fault, which is 
marked by a liae of springs, has been this — the Coal-measures and Mill- 
stone-grit cover and repose conformably on the beds below the Old Red. 
The whole of the limestone-formation may be locally divided as fol- 
lows, in descending order ; — 
1. The "whitehead limestone" and calcareo- arenaceous red and purple- 
coloured shales, graduating into the lowermost beds of Millstone-grit, 
or the equivalent of that rock, one bed being slightly oolitic, near St. 
Briavils, and at Coleford. Average thickness, 40 yards. 
2. Grey iron-stone formation. Grey and red-limestone beds. Thick- 
ness, about 42 yards. 
3. "Black-rock" limestone, calcareo-argillaceous shales, and "Fore- 
line" limestone, often called the " Mountain-limestone," graduating into 
the uppermost beds of Old Red; average thickness, probably, 15 yards, 
but very variable. 
The middle and lower divisions are moderately fossiliferous, but I am 
not aware of any organic remains having been discovered in the beds 
above the " Ironstone- formation," although, on Deans Mccnd, near 
Mitcheldean, I have observed a thin bed of purplish arenaceous 
limestone, on the upper surface of which there are certain ring and 
jiipc-like markings, which may probably be considered annelidal, or 
made by marine worms. In a bed near the bottom of the " Grey beds" 
some fine specimens of "fish palates" have boon found, and in the 
" Red beds" some entrochites of large size. These grey and rod beds 
arc highly crystalline, and average from two feet to a yard thick. The 
innumerable small joints, however, by which they ai-e traversed, render 
the stone valueless for building-purposes, although it is most extensively 
quarried for the supply of the iron-furnaces, as well as for burning into 
lime. 
But the real harvest for the palcconlologist is to be gained in the 
carboniferous shale-partings or ancient mud-beds, which are inter- 
stratified with the thin beds of limestone and calcareo-arenaccous 
shales that form the transition to the Devonian beds. The series which, 
ia all probability, represents the carboniferous shales of Devonshire is 
a perfect charnel-house of cncrinital remains ; and I know of no better 
spot for the collector than the section, or, in quarry-language, " loose 
end," which is obtained in an old quarry near the summit of Plump 
