| 1. | Uppermost; Coral-rag, three and a half feet. |
| 2. | Limestone, containing an abundance of shells, particularly of Trigoniæ ([p. 412]), &c. four and a half feet. |
| 3. | Portland sand, of an olive-green colour, three feet. |
| 4. | Kimmeridge clay. |
Some shells are extremely numerous; principally of the genera Trigonia, Gervillia, Pecten, Ostrea, Terebratula, &c.; fine Belemnites also occur. The oolitic structure is very apparent in the upper beds of limestone.
Swindon, Wilts.—Fourteen miles beyond the Farringdon station of the railway, we arrive at that of Swindon. About a mile from this station, on the rising ground to the south, stands the little, and formerly retired, town of Swindon. Here, when a schoolboy, my curiosity was strongly excited by the so-called petrified "ram’s horns," and "oak," so abundant in the solid masses of stone in the neighbouring quarries, and which daily came under my notice in my rambles around the town. It is indeed a locality most prolific in the Ammonites and other shells, and in the fossil wood peculiar to the upper division of the Oolite formation—the Portland beds; the hill on which the town is built consisting of those strata; the Kimmeridge Clay, on which they rest, is exposed in the railway cuttings in the valley on the north. There are two little Inns, the Bell and the Goddard Arms, where the visitor may meet with accommodation. The quarries, which are in the immediate vicinity of the town, abound in Ammonites, Trigoniæ, and other shells: and some layers are entirely composed of the casts of several species. The Ammonites are principally of two kinds, viz. A. biplex and A. triplicatus, and vary in size from a few inches to upwards of three feet in diameter; the specimens are casts only, no vestiges of the shells remaining. At Aylesbury the same species occur in clay, with the shells entire (see [p. 481]). A large collection may be made in a few hours; and from some of the quarry-men the less common forms may probably be obtained. Casts of the bivalves called Gervillia and Perna abound in the quarry on the right hand of the road. I have collected from this place, in addition to those above mentioned, casts of the genera Buccinum, Cardium, Cytherea or Venus, Nerita, Terebra, Pullastra, Pecten; and of the large species of Pleurotomaria which occurs in the Kimmeridge clay of Hartwell, with the shell perfect ([p. 428]); also vertebræ of Ichthyosauri.
A section of the strata from Swindon to the nearest point of the chalk hills would pass over, in succession,—1. Portland Oolite; 2. Lower Greensand; 3. Galt; 4. Upper Greensand; 5. Chalk-marl; and, 6. Chalk.
EXCURSION TO CHIPPENHAM AND CALNE.
Chippenham and Calne.—In from three and a half to four hours the traveller from London reaches the town of Chippenham, ninety-three miles from London, and situated on the Oxford clay; the locality where Mr. William Bye obtained those interesting specimens of Belemnoteuthis, that contain vestiges of the soft bodies and arms (see [page 459], and [Lign. 145]).
Calne, about six miles from Chippenham, stands on Oolitic limestone; and the quarries around the town have long been celebrated for the perfection and abundance of their fossil remains; particularly of various species of the turban echinites (Cidarites, see [p. 316]), and their spines. A day or two at each of these towns will be well spent by the geologist and the collector of organic remains.
Bath and Bristol.—The immediate vicinities of these cities are rich in interesting localities for the geologist. A visit to the public museums in Bath and Bristol cannot fail to gratify the student, and will at once point out to him the places most worthy his examination. That of Bristol is admirably arranged, and contains, among other treasures, the specimen of fossil Squaloraia (see [p. 596]); the remains of the reptiles of the magnesian conglomerate, the Thecodontosaurus ([p. 713]); and the celebrated collection of Crinoidea ([p. 283]) formed by the late Mr. Miller.
EXCURSION TO CLIFTON.
Clifton.—The stupendous rocks of mountain limestone which flank both sides of the Avon in its course from Clifton to the Severn are too well known to render a general description necessary, and our limits will not admit of details. The geological student should first obtain a coup d’œil of the appearance and position of the strata, by sailing down to the embouchure of the river in a steam-packet, and afterwards visit on foot the most interesting localities. On the right bank of the river, near the "Black Rock," the teeth of several kinds of fishes of the genera Psammodus ([p. 587]), Hybodus ([p. 591]), Ceratodus ([p. 587]), &c. may be obtained, and shells and corals of the mountain limestone. Polished specimens of the coralline marbles may be purchased at the shops.