Arthur Aikin

“ The sandstones which make part of the first thirty strata, are fine grained, considerably micaceous, and often contain thin plates or minute fragments of coal. The thirty-first and thirty-third strata are coarse-grained sandstone entirely penetrated by petroleum; they are, both together, fifteen feet and a half thick, and have a bed of sandy slate-clay about four feet thick interposed between them. These strata are interesting, as furnishing the supply of petroleum that issues from the tar-spring at Coalport. ”

“ The independent coal-formation is found immediately adjacent to the red sandstone from Wombridge in the parallel of Wellington to Coal-port on the Severn, a length of about six miles; its greatest breadth is about two miles. It rises west a little to the north at an angle of about 6°. It is composed of the usual members, namely, of quartzose sandstone, of indurated clay, of clay-porphyry, of slaty-clay, and of coal, alternating with each other without much regularity, except that each bed of coal is always immediately covered by indurated or slaty-clay and not by sandstone. ”

“ Of this greenstone there are several varieties. Sometimes it is of a dark bluish-green colour, passing into iron-grey; is massive, glimmering, of a coarse-grained uneven fracture, and breaks into irregular rather blunt-edged fragments; it gives a pale greenish-grey streak, is considerably heavy and difficultly frangible. When immersed in an acid an effervescence is perceived from various parts of its surface: by examination with a lens it appears to be composed of hornblende and felspar, with a little calcareous spar and mica. ”

“ The general cultivation of the surface of this hill is a great obstruction to minute research, a difficulty that fortunately does not apply to the other great deposit at Steeraway, where an excellent opportunity of observation is afforded by the limestone quarries at that place. ”

“ That the Viger coal, with its superincumbent clay, occupies thickness of about twelve feet at Madeley, is diminished to three feet at Lightmoor, and is entirely wanting in all the collieries which lie to the north of the latter. That a bed of clay, usually known by the name of the upper clunches, bears a thickness of from fifteen to twenty-six feet in all the above mentioned collieries, except that of Ketley, where it is entirely wanting.
The rock upon which the coal formation rests, is either die-earth or limestone. ”

“ The first coal forms the ninth bed from the surface, at the depth of one hundred and two feet, and is not more than four inches thick: it is very sulphurous. In the space between this and three hundred and ninety-six feet, lie nine other beds of stinking coal, none of which exceeds the thickness of seven inches except the lowest, which is a little more than a foot and a half thick. The first bed that is worked is a live-foot coal at the depth of four hundred and ninety feet, between which and the big-flint sandstone, already mentioned, are a ten-inch and a yard coal. ”

“ Beneath the quartz-grit lies a very extensive bed of claystone or compact felspar (for it presents the characters of both these minerals in different places, and even occasionally passes into jasper) . Sometimes it is very distinctly slaty and stratified, which is particularly the case with the lowest part of the bed, which rests on greenstone and amygdaloid, and occasionally exerts a pretty strong action on the magnetic needle. The craggy eastern side, both of the Wrekin and of Caer Caradoc, consists of the slaty variety of this rock in nearly vertical strata ”

“ Detached lumps of galena are often found on the surface, and a few small veins of the same mineral have been traced in various parts, but chiefly near the southern extremity of the range; cavities lined with and occasionally full of petroleum occur at the northern extremity, where it comes in contact with the coal-formation. The names of the hills constituting this tract of limestone are, Mochtre Forest on the borders of Herefordshire, Norton Walls, Feifton Forest, Munslow Hill, Mogg Forest, Benthal Edge, and Lincoln Hill. ”

“ The Staffordshire strata dip rapidly towards it in a western direction, while those of Shropshire decline towards it, at a lower angle, in an eastern direction. Whether they actually past under the sandstone, or terminate abruptly on coming in contact with it, has not yet been demonstrated; many intelligent miners are of the former opinion: but to me, the latter appears the more probable, from an observation that was made a few years ago in Welbach colliery near Shrewsbury. In this coal-field, as in the two before mentioned, the strata dip towards the sandstone ”

“ Under the claystone occurs an unstratified trap-formation which constitutes the great mass of the Wrekin, the Lawley, Caer Caradoc, Ragleath and Hope Bowdler hills, the various component parts of which will be best understood by arranging them under the general heads of felspar rocks and greenstone rocks. ”

“ The principal argument in favour of motion by depression, is the absence of any unstratified rock between the elevated stratum and that which naturally lies below and in contact with it; to which may be added the fracture and disturbance of those superincumbent beds which lie on the dip of the elevated stratum. ”

“ They are also much more closely accumulated on each other, and are generally elevated at a higher angle, as they advance from the south to the north: thus, the same succession of strata, which occupies a line of between four and five miles in the parallel of Caer Caradoc, is contracted within a space of less than three quarters of a mile in the parallel of the Wrekin. ”

“ Besides vegetable impressions, it contains a few shells; small mytili in particular are found in the iron ore, called crawstone, which lies immediately above the little flint. One of the most remarkable beds of this clay is called the pinny' or penny-measure. It is the sixty-third in number, lying the next below the big flint, and occurs at the depth of five hundred and eighty feet. Its thickness in Madeley colliery is scarcely seven feet, but at Ketley is full twenty-seven feet ”