454 
THE CRETACEOUS ROCKS OF BRITAIN. 
There is probably another 8 or 9 feet of Melbourn Eock below 
the quarry floor, and the total thickness of the Middle Chalk 
here will therefore be about 88 feet. The beds dip at 3 or 4 deg. 
to the north. Prof. Barrois gave an account of this section in 
1876,* but the thicknesses he assigns to the several beds are all 
too great. He records the following fossils from the Terebratulina 
zone : — 
Inoceramus mytiloides. Rhynchonella Cuvieri. 
„ Brongniarti. Terebratulina gracilis. 
Pinna decussata. 
The large quarry on Cley Hill, west of Warminster, shews a 
similar section, but exposes more of the Melbourn Eock at the 
base, find the total thickness appears to be rather less. Mr. 
Scanes has recently made a careful measurement and found it to 
be about 78 feet. 
The only good exposure of the Middle Chalk near Westbury is in 
the large quarry on the Long Eiver Eoad. The weathered face near 
the road shows about 8 feet of yellowish-white chalk, hard nodular 
beds alternating with soft marly layers containing loose nodules ; 
Inoceramus mytiloides and Rhynchonella Cuvieri are abundant. 
I was informed by workmen that the pit was formerly worked 
down to a very hard rock, and that the lowest layers came out in 
large blocks weighing over a ton in weight. This was evidently 
the Melbourn Eock, but is not now visible. 
On the inner face of the quarry the beds are more massive and 
less weathered; the lower part is hard and contains some Inoce- 
rami, but the higher beds belonging to the Terebratulina zone 
are difficult to reach. The height of this inner face must be nearly 
70 feet above the floor of the quarry. The total thickness of Middle 
Chalk here must be from 90 to 100 feet, as the outcrop of the 
Chalk Eock is some distance above the top of the quarry. 
The outcrop of the Melbourn Eock can be seen imrnost of the road- 
wnys which ascend the escarpment near Market Lavington and 
Urchfont, but there are no good exposures of the overlying beds 
along this tract. Some 20 feet of the Terebratulina zone are, how¬ 
ever, exposed below the Chalk Eock in a quarry on Eedhorn Hill, 
south-east of Hrchfont. 
Mr. Bennett found an exposure of the Rhynchonella Cuvieri zone 
in a pit about two miles south of Marden Church, showing:— 
feet. 
Rather soft white chalk ------- l 
Hard nodular chalk - - 5 
Smooth chalk, passing down into greyish laminated marl - § 
Hard smooth chalk ..--1 
Hard nodular chalk in two beds, separated by a thin seam of 
marl - - - - - - - - - -2 
From these beds he obtained Inoceramus mytiloides , Rhynchonella 
Cuvieri , and Discoidea Dixoni. 
* Recherches sur le Terrain Cret. Sup. p. 58, 
