CAVERN OF THE HIGH TOR.

Visit to the Cavern of the High Tor.—After the visitor has taken a general view of the romantic scenery around him, a visit to the cavern at the foot of the High Tor will enable him to comprehend the nature of those physical changes which have imparted to this district its picturesque character. Descending into the valley and passing northwards, through the only street in Matlock Bath, along the banks of the Derwent, which are beautifully overshadowed by copses and forest trees, the bold cliff of mountain limestone, called the High Tor, the most imposing feature in the dale, suddenly appears on the right bank of the river. This rock rises to the height of four hundred feet; the upper half forming a bare and nearly perpendicular wall of limestone; the lower portion being concealed by brushwood and luxuriant foliage to the river s edge. At this spot, a rude wooden hand-rail is stretched across the Derwent, which is here of considerable breadth, and dashes along over fallen masses of rock in its course towards the south. The High Tor ([Lign. 270]) consists of a capping of Drift and of Millstone grit (2); of a series of beds of limestone with encrinites and shells, slightly inclined southward (1); of a layer of volcanic matter, termed in Derbyshire toadstone, from its mottled yellow and greenish appearance (3); and of a bed of Trap, or toadstone (b), at the base, and near the floor at the entrance of the fissure or excavation in the limestone forming the cavern (a); which trap rock also appears on the opposite bank of the river (c), beneath the highly inclined and dislocated masses of limestone, forming part of the base of Masson Hill. The upper bed of toadstone (3) cannot be seen, for the face of the cliff (although represented bare for the sake of perspicuity in the plan, [Lign. 270]) is entirely concealed, half-way up, by dense foliage; but an intelligent miner assured me that such was the fact, and that, in sinking a shaft in the opposite hill, toadstone was found in a corresponding situation. Upon entering the cavern, which is not of considerable extent, the first phenomenon to be observed is the bed of toadstone, which protrudes near the floor, beneath a stratum of limestone. The limestone in contact with the trap is in some places changed to a light green colour, and has a slaty texture, from the effects of intense heat under great pressure; it is often permeated with veins of pyrites, and white calcareous spar. The inner recesses of the cavern are literally covered, both on the floor and sides, with very large rhomboidal crystals of carbonite of lime, of the form commonly called dog-tooth spar; the cave surpasses, in this respect, every other in Derbyshire.

G. A. M. delt. J. Whimper, lignt.

Lign. 270. Section across the Valley of the Derwent, at the High Tor, Matlock.

Fig.1.—The High Tor, composed of strata of Mountain Limestone.
2.—Capping of Millstone Grit and Drift.
2.—Supposed position of an intrusion of Trap.
2.—Cliff of limestone on the opposite side of the valley.
a.—Entrance to the High Tor Cavern.
b.—Trap seen at the bottom of tile Cave.
c.—Trap beneath the limestone on the opposite bank of the Derwent.

Within a few hundred yards of the cavern, a gallery has been driven into the cliff, and a vein of lead (galena) discovered, and worked with some success. Tine masses of blue fluor (provincially termed blue John) and double refracting calcareous spar were also obtained. On the opposite bank of the Derwent, beneath the limestone, and extending along the road-side for two or three hundred yards, a bed of toadstone, evidently the continuation of that at the base of the High Tor, is distinctly exposed.

Proceeding northwards, the line of mural precipices, of which the High Tor is the most elevated point, gradually descends; but there is a bold and bare rock, called the Church Tor, from the church of the village of Matlock being situated near its summit, that requires particular remark; for on the face of this cliff the strata present a series of curves, or rather arches, nowhere broken, but having such an appearance as would result from an expansive force from beneath uplifting a group of horizontal strata, while yet in a soft or plastic state. The upper beds of limestone at the Church Tor abound in marine shells (Spirifer, see p. 390, particularly the large species, S. giganteus). Such are the appearances presented by the strata in this locality, on the right bank of the Derwent. On the opposite side of the valley are beds of limestone, many of them varying in mineral constitution from those we have examined, being of a light yellowish dun or cream colour (hence called Dun-stone), and containing magnesia; in these strata traces of fossil plants are occasionally found. These magnesian limestones are of a granular texture and extremely hard; they are said to be very rich in lead and calamine, and have been extensively worked. The prevailing rocks on this (the western) side of the valley belong to this group.

FORMATIONS OF DERBYSHIRE.