196 
CARBONIFEROUS LIMESTONE SERIES. 
(6) The Dibunophyllum (D) Beds. 
These are only seen in the eastern part of the district, not being 
met with to the W. of Tyntesfield. In the Leigh Woods area 
there is a double development, a small northern wedge-shaped 
mass in the neighbourhood of Stoke Leigh Camp being formed 
by the D-beds in their normal position, while in the neighbour- 
hood of Rownham Hill the same beds occur repeated by the 
Observatory Hill fault. The exposures in the railway cuttings 
by the Avon were briefly described with fossil lists by Vaughan. 1 
Apart from the exposures in the Avon Valley, those of the 
wedge-shaped mass are poor and scanty. The best are in the 
crags which extend from the northern vallum of Stoke Leigh 
Camp down to the Avon. Here the various lithological types of 
the upper D i and lower D 2 beds may be easily recognised, 
particularly the coarse oolites, red grits, and bands full of 
Productus. Near the northern extremity of the wall which runs 
north eastwards from Beggar's Bush comer, the lower more 
massive limestones of D 1 are seen and contain the characteristic 
Cyathophyllum murchisoni. Apart from those in the Avon Valley 
the only exposure of D-beds as repeated by the fault, to be seen N. 
of Ash ton Park is at the well-known quarry on Rownham Hill. 2 . 
Much of the rock here is a coarse oolite. The southern boundary 
of the D-beds in Ashton Park is remarkably irregular, and we 
clearly have here a shore-line of Triassic age. The upper D-beds, 
which include much red grit form wooded promontories, with the 
Triassic rocks extending up the inlets between them. Church 
Wood must at one time have formed an island in the Triassic sea. 
The lower D i-beds which as in the Avon Section contain little 
or no grit, and are often coarsely oolitic, are seen in an old quarry 
J mile W. of Rownham Hill Lodge, and at a number of points 
on the hillside to the E. of New Barn. Many of the char- 
acteristic D 1 fossils may be readily found. Oolitic D 1 is also 
seen in a quarry in darken Combe. Ashton Hill and the neigh- 
bourhood of Providence, are mainly composed of red grit 
associated with red rubbly and often oolitic limestone. There 
are numerous exposures of both these rock-types, and in par- 
ticular there is a considerable quarry in massive grey, coarsely 
crinoidal and foraminiferal limestone on Ashton Hill 300 yards 
W. of the Convalescent Home. To the W. of Providence Lane 
the surface is very irregular owing to the old shallow workings 
for iron ore, which appears to occur in bands interbedded with 
the limestone. The cutting which traverses Iron Plantation 
was doubtless made in search of ore. The material thrown out 
in making a series of bunkers for the Long Ashton Golf Club 
about J mile W. of Iron Plantation enables the boundary between 
S and D to be very accurately fixed. 
1 Bristol Paper, pp. 197-199. 
2 Ibid, p. 197, and B.N.S. paper, p. 121. 
