GEOLOGICAL NOTES OF VARIOUS PLACES ON THE LINE OF THE GREAT WESTERN RAILROAD, FROM LONDON TO CLIFTON.

That splendid railway, the Great Western, by which the geologist may be transported in five or six hours from the Tertiary strata of the metropolis to the magnificent cliffs of Mountain limestone at Clifton, exposes in its course several fine sections, and passes within a moderate distance of some interesting localities of organic remains.

This railroad traverses the Tertiary strata by Ealing, Hanwell, and Slough, entering the Chalk near Maidenhead, and pursuing rather a circuitous route to Wallingford, beyond which station it passes over the Oolite, and displays some bold sections of the limestones and clays of that formation. Near Bath it emerges on the Lias, and crossing a narrow belt of the New Red, passes on to the Carboniferous strata of the Bristol coal measures.[792] In this route, there are four places particularly deserving a visit from the geological student, and collector of organic remains, namely, Farringdon, Swindon, Caine, and Chippenham.

Visit to Farringdon.—The railway station is reached in from two to two and a half hours from London; and an omnibus meets the morning and evening trains, to convey passengers to the town of Farringdon, which is about five miles distant.[793] There are two Inns in the town, the Crown and the Bell, where comfortable accommodation may be obtained.

The town is situated in a valley, between Farringdon Hill, an eminence seen from a considerable distance in the approach from Oxford, and Badbury Hill (see Lign. 269). A small stream divides the town into two tithings, called Port and West-port, and flows into the Thames on the north. The summits of the highest eminences near Farringdon consist of beds of sand and gravel, resting on Coral Bag and Kimmeridge Clay, and belonging to the Cretaceous formation, being the littoral deposits in this area of some sea of that period. The Lower Green or Shanklin Sand, the Galt, Chalk-marl, and Chalk successively appear in the valley below Coxwell Furze up to the White Horse Downs.

I have not observed any organic remains in the strata on the top of Farringdon and Badbury Hills, but from the pits in the low country numerous fossil sponges and other amorphozoa (see pp. 227-229) maybe obtained. One of the most productive "gravel-pits," as they are here termed, is situated on the road to Little Coxwell, about three quarters of a mile from Farringdon. It lies on the left of the road leading to the pretty village of Shrivenham. In this pit, the strata consist of a coarse aggregate of siliceous particles, with some lenticular masses in the state of compact conglomerate; the lower beds are of a whitish grey, the upper of a deep ferruginous colour. The Windmill public-house, close by, is kept by the owner of the pit (Panting), and specimens of the "petrified salt-cellars" (see p. 228) and other sponges may generally be obtained of the inmates; but the collector, in a few hours, will be able to gather an extensive and interesting collection; the pick-hammer, Lign. 266, fig. 2, will be found the most convenient instrument. There are two other pits within a moderate distance of Panting s pit, which are also rich in fossils. The principal organic remains to be obtained from these beds are the zoophytes figured p. 227, and Wond. p. 637. The reader should recollect that the beautiful cup-shaped sponge, Chenendopora fungiformis (Lign. 71), is the "petrified salt-cellar" of the quarry-men. As many specimens as possible of the interesting coral, Verticellipora (p. 227, Lign. 70, fig. 4,) should be procured, to examine the internal structure at leisure. The cup-shaped sponges should be collected uncleared, for they are often full of minute corals, shells, echinital spines, &c. There are also numerous specimens to be met with of TerebratulÆ, OstreÆ, Nautili, and other shells; also rolled Belemnites from the Oolite, and bones of Plesiosauri and Ichthyosauri.

Fossils of the Coralline Oolite.—At a short distance from the town there is a large quarry of Coral-rag, called Lamb-close-pit, from which Cidarites (p. 316) and spines, and several species of corals and shells may be procured. Occasionally Ammonites and Belemnites are met with in the limestone at this place.

Stanford pit, about three miles south-east of Farringdon, is well worthy of a visit; it consists of the following strata:—

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.

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.

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’oeil 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.

Portishead, a pretty little village on the south-east bank of the Severn, is well worth a visit; and, by going in the morning steamer and returning in the evening, several hours may be agreeably spent along the shore below the hotel; and fossil plants and shells, from the blocks of millstone grit, and numerous rock specimens may be collected.

A sail to Chepstow, and up the Wye as far as Tintern Abbey, returning on foot, or in a carriage, by Piercefield to Chepstow, is an excursion replete with the highest interest and enjoyment. The picturesque beauties of the Wye are dependent, like those of Clifton and Matlock, on the disruptions which the strata of mountain limestone have sustained. The magnificent scenery as we pass up the river, and the interesting associations connected with the ruins of Tintern Abbey, cannot fail to delight the traveller; but the enchanting scene that bursts upon the sight from the heights of Piercefield is magnificent in the extreme, and equal to the grandest views on the Rhine. Looking down from those elevated pinnacles of rock, which are covered with the most luxuriant vegetation, and crested with forests of pine, oak, and beech, we perceive the Wye pursuing its tortuous course at our feet, and winding along, around promontories of limestone, towards Chepstow; while immediately beyond, and apparently separated from the opposite bank of the river only by a precipitous rampart or mountain limestone, the Severn appears as a vast inland sea, bounded in the remote distance by the country around Gloucester, and extending on the right to the Bristol Channel.

Among other interesting geological sites within a few miles of Clifton and Bristol, may be mentioned—

1. Aust Cliff; a section of the Lias, from which many interesting fossils have been procured.

2. Banwell Cave; which is particularly deserving of examination (see p. 809).

3. Cheddar Cliffs; which are equally interesting to the geologist and to the lover of picturesque scenery. They are about twenty miles from Bristol; and a carriage and pair will be required, if the visitor intends to return the same day. The best arrangement is to visit the cavern at Banwell, remain in the neighbouring town the following night, and make an excursion to Cheddar Cliffs the next day.

There has lately been opened at Cheddar a cavern which surpasses in the beauty of its stalactites any hitherto discovered in England. The Rev. W. D. Conybeare states, that it is the only one that at all realizes any idea we have of the far-famed Grotto of Antiparos. It consists of one grand arch, or porch, and three or four lateral branches and narrow fissures, about ten or twelve feet broad, and from thirty to forty feet high, vested and draped with the most fantastic hangings of stalactite. The floor is a mass of stalagmite, covering a bed of gravel of the mountain limestone, which fills up about ten feet of the bottom. I am not aware that any fossil bones have been observed.

When visiting Banwell, inquiry should be made if there be any Cave at Hutton accessible to the visitor.

The above remarks must be regarded only as suggestions; for it would require a volume to particularize the geological objects of interest within a short distance of Bristol. The coal-mines in the neighbourhood of Bath and Bristol should be visited, and fossil plants collected.