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sufficiently hard for building purposes. It is developed at Stourport. The town of Birmingham is built principally upon it, and it is exposed near Wolverhampton.
The Bunter beds have not been identified with certainty south of Malvern, but there is a probability of their being represented in West Somerset and Devon (see p. 141). Near Malvern they are represented by 400 feet of red and white sandstones and conglomerate.
The Bunter sandstone yields a good supply of water, being in fact one of the most prolific of the water-bearing
The Bunter Conglomerate of Cannock Chase has, according to Mr. Molyneux, yielded lead and copper ores.
NEW RED MARL.
The Keuper beds which overlie the Bunter are divided into:
Upper.-Red and variegated marls with beds of sandstone, 800 to 3,000 feet.
Lower.-Sandstones (Waterstones') having a thickness
of 200 feet in Derbyshire and 450 feet in Lancashire.
There is, however, no hard line of demarcation between the two divisions. Keuper is a provincial German term.
Lower Keuper.-This division consists of thinly laminated micaceous sandstones and marls; also of white, brown,
This term was originally used by Mr. Ormerod because the surfaces of some of the beds had a watery appearance, like watered silk. The term as generally understood expresses the water-bearing qualities of the strata.
or reddish sandstone, with sometimes a base of calcareous conglomerate or breccia.
Prof. Hull has given the following general section of their succession :-
Waterstones (passage beds into the Red Marl).-Brownish
or white freestones, regularly bedded, with occasional
Basement beds.-Coarse, irregularly-bedded sandstones, calcareous breccia and conglomerate, with bands of marl and mottled calcareous beds similar to the Cornstones' of the Old Red Sandstone.
Many foot-prints of Labyrinthodonts (Cheirotherium) have been discovered in the Keuper Sandstones, and particularly in Cheshire. Perhaps the quarries at Storeton Hill, on the peninsula of Wirral, are the richest in these traces of ancient life.
The beds have been largely quarried for building purposes at Ombersley and Hadley.
In the neighbourhood of Pattingham and Tattenhall the basement beds have been burnt for lime.
The beds are exposed near Bromsgrove, Kidderminster, and Bridgenorth, near Wolverhampton, Rugeley, Colwich, Eccleshall, Hawkstone Hills, at Overton Scar, and in the Peckforton Hills, Cheshire. They are also seen at Delamere Forest (450 feet), Storeton Hill, in East Warwickshire, at Ashby-de-la-Zouch and Alton in Staffordshire, also in Derbyshire and Nottinghamshire.
Among the local stones may be mentioned the Bank Delf Stone of Bank Quarry near Melling; the Runcorn stone;
the Tinkersdale stone of Grinshill, Shrewsbury; the Durme Stone? of Drayton Basset, Tamworth; and the Kingwood Stone in the neighbourhood of Codsall.
The Lower Keuper sandstones of Alderley Edge have yielded much copper-ore.
Upper Keuper.-The uppermost deposit of the Trias consists very often of Red Marl.
It comprises a series of red and variegated marls, the red colour preponderating, and the beds being mottled with spots and streaks of a grey or green hue.
In the upper part the marl is softer and generally without. distinct lines of stratification, and it is usually much broken up and fissured by cracks or joints and miniature faults. The rock presents a rubbly appearance, and is often separated into small masses of a cuboidal or rhombic form. Interstratified with the marl there often occur beds of hard red and sometimes grey or cream-coloured marl, and sandstone.
The presence of carbonate of lime does not appear to be invariable, but the amount is sometimes so trifling as not to be detected by the application of hydrochloric acid.
These red and variegated marls were first identified with the Keuper of Germany by Sedgwick.
Beds of sandstone occasionally occur in the Red Marl. In the neighbourhood of Tewkesbury there is a bed of white sandstone 20 to 30 feet in thickness in the Red Marl.
In the Upper Keuper Sandstones near Taunton, Mr. C. Moore has discovered remains of Estheria minuta, fish, Labyrinthodon, &c.
Prof. T. R. Jones and Mr. Parker have described a series of Foraminifera from the Red Marl series at Chellaston near Derby.
The Keuper Marl forms fine rich meadow-land; the soil
is well suited for orchards and teazels. It was formerly largely used for marling ground: hence the number of old marl pits.
Alabaster or gypsum (hydrous sulphate of lime) occurs in abundance in some localities in the Red Marl or Gypseous marls of the Isle of Axholme, Newark and Orston, Nottinghamshire; Chellaston and Aston, Derbyshire; near Tutbury, Staffordshire; near Whitehaven, Cumberland; Syston, in Leicestershire; and at Watchet, in Somersetshire.
The purer and variegated kinds are manufactured into ornamental articles, the common sort (but that most largely worked) is converted by burning into Plaster of Paris, which being largely used in forming moulds for the Staffordshire potters, the alabaster is known as Potter's Stone. The very coarse kinds are used as top-dressing for soils.
Celestine, or 'Salt-stone' (Sulphate of Strontian), is found in some abundance in the Red Marl of Gloucestershire and Somersetshire.
Pseudomorphous crystals of rock salt occur abundantly in the Keuper sandstones and marls.
Fullers' earth is raised from the marl beds at Raddle Pits near Braithweel, north-east of Rotherham, also at Renton in Yorkshire; and at Taschbrook, one mile from Warwick, a substance probably of the same nature, as it was intended as a substitute for soap, was raised by the Earl of Warwick.'
In Cheshire and Worcestershire beds of Rock-Salt occur, interstratified with the lower beds of the Keuper Marl. In Cheshire, Prof. Hull considers that the Marl has a thickness little short of 3,000 feet. Our culinary salt is largely manufactured from the brine springs. Hence the term 'Saliferous' is sometimes applied to the Upper Keuper strata.
Among the localities are Droitwich and Stoke, in Worcestershire; Northwich, Sandbach, Anderton, Middlewich, 1 Conybeare and Phillips.
Lawton, Dirtwich, and Nantwich in Cheshire; and Shirleywich in Staffordshire.' Prof. Hull states that at Droitwich the salt has been extracted from the brine for upwards of 1,000 years.
The Rock-salt occurs at some places in a massive or granular form, at others in large cubical crystals; Gypsum is often found with it. It is usually of a dull red tint, and associated with red and pale green marls. When lighted up with numerous candles, the vast subterranean halls that have been excavated during the working of Rock-salt, present an appearance which richly repays any trouble that may have been incurred in visiting them.2
In Nantwich and other places in Cheshire where the salt is worked, the beds containing it are reached at a depth of from 50 to 150 yards below the surface. The number of saliferous beds in the district is five, and they vary in thickness from six inches to nearly forty feet; a considerable quantity of salt is also mixed with the marls associated with the purer beds.
The descent to the mines is by a shaft, used for the general purposes of drainage, ventilation, &c. The roof, which is about 20 feet above the floor, is supported by pillars about 15 feet in thickness. The Wilton mine, one of the largest, has been worked 330 feet below the surface, and from it, and adjacent mines, upwards of 60,000 tons of Rock-salt were annually obtained; a part of which was exported, and the rest dissolved in water, and afterwards reduced to a crystalline state by evaporating the solution.
The mines, however, are not the only sources from which salt has been obtained, and it is only since the year 1670, when the beds were discovered during an unsuccessful sink
1 The houses in which salt is manufactured are called Wych-houses. 2 For these and the following remarks I am indebted to Prof. Ansted's Geology (1844).