if any good sections of it should occur, it may be expected to reward the geologist amply for the trouble of an examination.* The next stratum in the descending order is the Marlestone. This formation consists of a series of beds of sandstone, marl, and sand, in various degrees of induration. It may be traced along the side of the Broadway Range, at about half the height up; and skirts Bredon Hill in the same manner, where it forms the summit of five or six flat-topped projections, half the height of the main range, and jutting out from it on the N. and E. sides. In Dumbleton Hill, which is of inferior height, it occupies the summit, proving, by the regularity of its occurrence in these hills, that the intervening vallies have been denuded, and that Dumbleton and Bredon Hills are correctly termed outliers. The Marlestone rarely possesses sufficient solidity of texture to qualify it for a building-stone, but in lieu of better materials it is. quarried in many places to repair the roads. The Marlestone of our district seems unquestionably to be the equivalent of the bed of the same name on the Yorkshire coast, which separates the Upper and Lower Lias Shales. In both localities it contains an abundance of fossils, including several species which are common both to Worcestershire and Yorkshire. In this neighbourhood the most numerous and remarkable fossils are, Belemnites, Gryphæa Gigantea, and Pecten Equivalvis. The following is a list of the fossils hitherto noticed in it, and probably many more might be added on a closer examination of the several quarries where it is exposed. Ammonita 5 species; Nautilus 1; Belemnita 1; Terebra 1; Turbo 1; Trochus 1; Mya 1; Lutraria 1; Unio? 3; Corbula ? 1; Tellina? 1; Astarte 1; Cardium 1; Modiola 1; Pinna 1; Avicula 1; Plagiostoma 4; Pecten 9; Ostrea 1; Gryphæa 1; Terebratula 8. Twenty-one genera; 45 species. We now arrive at a formation more important both in thickness and superficial extent than any hitherto described-the Lower Lias Shale, commonly known by the simple name of Lias. This stratum occupies nearly the whole of the Vale of Evesham, and extends from 200 to 300 feet up the sides of Bredon and Broadway Hills. Its total thickness is probably upwards of 500 feet. At Bretforton it has been sunk into more than 300 feet, in quest of coal, without being perforated. This excavation was commenced three years ago by a sanguine speculator, in spite of the warning advice of geologists, and after a great sum expended, is at last given up as hopeless. All scientific geologists know that true coal is only to be found beneath the New Red Sandstone, and that to seek for it in the Lias which is above that formation can only end in disappointment. And such is the enormous thickness of the New Red Sandstone, (as shewn by Mrs. Brown's excavation, which will be noticed hereafter,) that it is scarcely less chimerical to seek for it there, except, indeed, in the very lowest beds of that formation. If by diffusing a knowledge of the general principles of * An account of this stratum and its organic remains, will be found in Mr. Murchison's excellent little work on the Geology of Cheltenham, just published. geology, the Worcestershire Natural History Society shall prevent future speculators from sinking their fortunes underground in places where they will never draw them up again, our infant Society will not be without its use. The Lias Formation consists here, as elsewhere, of a series of black or blue shales, producing, by exposure to the atmosphere, a cold, stiff, clay soil. At the lower part of the formation, thin beds of limestone occur, from 2 to 8 or 10 inches thick, which produce excellent lime, but when used as a building-stone are apt to shiver with the frost. At Binton, near Bidford, and at Haselor, these beds are thin, smooth, and of fine quality, and are used for flooring and other purposes. Experiments, partly successful, have been made to apply the Haselor stone to lithography. It is well adapted for the lithographic ink, but is not suited for crayons. The strata we have hitherto described are very regular and conformable in their arrangement with respect to each other, but the Lias presents us with an extensive fault or break in the strata, by which the Red Marl beneath is unexpectedly exposed on the surface. This fault has been traced from near Netherton on the S. to Lower Bentley on the N., a distance of 15 miles, and is distinguished on the map by a narrow strip of Red Marl running towards the S., with Lias on each side. From Netherton to Radford, on the Worcester and Alcester road, this fault is marked by a shallow valley, from half-a-mile to a mile in width, crossing the valley of the Avon, and interrupted near the middle of its length by the Cracombe Hills. Throughout this space the eastern side of the valley is the highest and steepest, the rise on the W. being very gradual. This valley is one of those which geologists. term vallies of elevation, being a gap, caused by strata separating and sloping off to either side in consequence, as they suppose, of an elevation of the strata beneath. But as the same effect, (as far at least as relates to level,) would ensue from the depression of two neighbouring districts, as from the elevation of some point between them, it would perhaps be better to give to vallies of doubtful origin a name founded, not on theory, but on facts, and to term them anticlinal vallies, that is, vallies in which the strata on either side dip away in opposite directions. The portion of Red Marl exposed by the fault in question, is at first a narrow strip, with a regular width, of about half-a-mile, commencing near Netherton, and passing between Cropthorne and Charlton, whence it spreads out to a mile in width, reaching from Cracombe nearly to Chadbury. The Cracombe Hills cause an interruption to the anticlinal valley, and the Lias, which is continued uninterruptedly along their summit, forms a kind of bridge, connecting the Lias on the two opposite sides of the line of fault. The Red Marl rises about three quarters of the height of these hills, and may be traced dipping beneath the Lias, both on the E. side and the West, Beyond Cracombe Hill the valley resumes its course as far as Rouse Lench and Radford, with a width of half to three-quarters of a mile. The eastern limit of the Red Marl follows the brow of a steep bank to Abbot's Lench, and an isolated patch appears in a valley about a mile to the E. of that place. The Lias caps the hill between Rouse Lench and Abbot's Lench, and then turning to the E., appears no more on this side of the line of fault. The western limit of the Red Marl passes near Bishampton and Abberton, and crosses the Alcester Road a short distance W. of Radford. Up to this point, the break in our strata has been marked by an anticlinal valley, but from hence to Feckenham it assumes the form of a fault properly so called, the Red Marl being raised up, and forming a long range of hill, with the Lias on the W. abutting against it at the base. This is best seen by Section II., taken near Inkberrow. The Lias, as before observed, extends no farther than Rouse Lench on the E. side, but on the W. it continues past Little Inkberrow, Morton-under-Hill, and Feckenham, nearly to Lower Bentley, which is its furthest northern point in Worcestershire. At Feckenham, and near Bentley, the Red Marl is again seen to dip to the westward, and apparently to run under the Lias. Although the extent of the Lias in this county may be best seen by inspecting the map in the Society's Museum, yet it may be useful to give a general sketch of the line pursued by the junction of the Lias and New Red Sandstone or Red Marl. About three miles from Alcester, on the road to Stratford, is a hill composed of Lias, with Red Marl at the base; the former stratum extending northward, but to what distance has not yet been ascertained. From this point the lower junction of the Lias extends towards Bidford, and crosses the Avon about a mile E. of that town. It soon afterwards turns westward, and occupies the summit of a steep bank or cliff, with the river at the base, as far as Salford, whence the ridge turns to the southward, and is known by the name of Cleeve Bank. The river still keeps close to the foot of the bank, the sides of which are composed of Red Marl, and the summit of Lias. This continues to near Littleton Ferry, whence the boundary of the two formations is obscurely defined, but appears to pass near Norton, and turning to the N., to follow the eastern foot of the hills on which Atch Lench stands, as far as the Worcester and Alcester road, which it crosses for a short distance; it then sweeps round to the westward and forms the hills above Rouse Lench, before mentioned. Having already described the form assumed by these strata throughout the line of fault, we will resume the line of junction at Lower Bentley, where that description terminated. From near Lower Bentley the Lias passes about one mile S. E. of Hanbury, and thence at the back of Meer Hall to Goose Hill, and on the north of Trench Wood to Crowle, its course being for the most part marked by a low range of hill. At Crowle is a good section of it showing very distinctly its junction with the Red Marl. From Crowle, the line of junction crosses successively the roads to Alcester, Evesham, and Pershore, and then turning due S., passes close to Pirton, and across Croome Park, where it forms a low bank, with the house at the foot and the gardens upon the top. Beyond Croome the Lias runs to the S. for about three miles, and turning to the westward past Ripple, it stretches thence to Tewkesbury. The nearest point at which the Lias approaches Worcester, is on the Pershore Road, where it reaches within 33 miles of Worcester Cross. The Lias of our neighbourhood though not so productive in organic remains as it is in Dorsetshire and Yorkshire, contains, notwithstanding, in some of its beds, considerable abundance and variety. The vast Saurian Reptiles for which Lyme Regis is so famous, though rare, are not wanting in our district. Vertebræ of the Ichthyosaurus have occurred at Coltknap Hill, at Abbey Manor, and at Haselor, where also a fine vertebra of the Plesiosaurus was found, which has been presented by Mrs. Browne to our Museum. These facts suffice to render it highly probable that good specimens of these magnificent reptiles may occur in our neighbourhood, and lead me to hope that the interest excited by our Society in the cause of geology may be the means of saving many valuable fossil specimens from the ruthless hammer of the quarryman. The most conspicuous fossils of our Lias are the Plagiostoma Giganteum, and an oval bivalve, apparently the Unio Hybridus of Sowerby, (Min. Con. pl. 154,) but belonging to a new and undescribed genus, which last is very common in some of the lower beds of the Lias. Besides these the Gryphæa Incurva, the neverfailing attendant of the Lias in nearly all countries, is in some parts of our district very abundant. The following is a list of the genera I have hitherto noticed. Ichthyosaurus 1 species; Plesiosaurus 1; Ammonita 7; Nautilus 1 ; Belemnita 1; Trochus 1; Turritella 3; Orbicula 1 ; Venus 1; Astarte 1; Lucina 1; Unio? 2; Pinna 1; Avicula 2; Arca 1; Nucula 1; Ostrea 1; Gryphæa 2; Pecten 1; Plagiostoma 2; Modiola 2; Terebratula 1; Serpula 1; Cidaris 1; Pentacrinus 1. Twenty-six genera, 38 species. Before dismissing the Lias formation I ought to mention certain substances, which in some parts of it, are not unfrequent. These are hard masses of stone in the form of a cylinder, or truncated cone, from one to four inches in diameter, and about the same in length, Their surface is rough and uneven, with sometimes faint irregular ridges in a circular direction. When broken, they appear composed of a hard marble-like stone, containing fragments of shells. These bodies appear to be the nuclei of nodular concretions, such as are common in many formations, the softer parts of which have been decomposed. The lowest stratum which occurs in the Vale of Evesham, is the New Red Sandstone of geologists. This formation which composes the greatest part of Worcestershire is seen to dip under the Lias, whose escarpment generally forms a low range of hill along the northern and western borders of the district which it occupies. The New Red Sandstone formation possesses great uniformity of character throughout England, and in our district is not marked by any peculiarities. The uppermost beds consist here, as elsewhere, of a red friable marl, producing a rich strong soil. The highest bed of all, next to the Lias, is commonly of a whitish or grey colour, but in texture much resembling the Red Marl beneath; it is seldom schistose like the lias, but breaks into fragments in all directions. Wherever circumstances admit of a close examination of the union of this formation with the last, the transition appears quite sudden and well defined, but without any marks of violent action. The New Red Sandstone is quite conformable with the lias, and in the case of the fault before described, the disturbing force has affected both formations alike. The upper part of the New Red Sandstone in Britain has in no instance, I believe, supplied the geologist with fossils, and its list of mineral contents is very scanty. The only mineral contained in the Red Marl of this district is gypsum, which occurs sparingly near Cracombe and at Hasler, but is rare, I believe, in other parts of the county. Of the salt which at Droitwich and Stoke Prior forms a never failing source of prosperity, no traces exist in these upper strata. At Inkberrow, the extensive fault before mentioned brings to the surface the sandstone beds, which in most parts of England underlie the Red Marl. These beds are there quarried for a variety of uses. Their position with respect to the Lias is seen in Section II. The vast thickness of the New Red Sandstone formation is proved by the shaft sunk in 1804, by Mrs. Brown, of Hasler, in quest of coal. The following is the best account of the strata that can now be procured, and geologists may regret that a more exact account was not kept of so deep and interesting an excavation. Lias beds, about.. Grey and red strata Black strata.... 15 0 Red and white beds with gypsum. 387 9. (At 582 feet, a thin vein of coal.) Total.......... 807 9 Having now traced the strata of the Vale of Evesham in succession, as far as that district is considered to extend, the investigation of the rest of the county is left to others. It only remains to give, by way of an appendix, a sketch of what are commonly called diluvial deposits, as far as these occur in our district. The deposits of gravel, sand, and clay, which in most parts of the world lie in irregular patches upon older rocks, have been by many geologists referred to the Mosaic deluge. But recent observations seem to shew that these deposits have not all been simultaneous, and that granting some of them to originate in the Mosaic deluge, others have been caused by irruptions antecedent to that period. Be this as it may, there is nothing, I think, in our district to prove that the diluvial beds, which are there very abundant, are not the result of the Mosaic deluge alone. |