The coal-field of Oawestry is situated on the western verge of the county, and is quite distinct from those already noticed. The pro ductive portion of it is very limited, occupying a small area between Oswestry and the hills of Llanvorda, Trefonen, Treflach, and Sweeney. The carboniferous limestone is better developed. here than in any other part of the county. It separates the millstone-grit from the older Silurian rocks, and has a maximum thickness of 500 feet.
The coal-fields of Shropshire remaining to be noticed are situated on the south side of the county. The Titterstone Clee lIill coal-field lies between the towns of Ludlow and Cleobury Mortimer. At Corn brook and Kncwlbury in this field there are four principal beds of coal, which vary in thickness in different parts; and beneath the uppermost bed the shale contains concretions of ironstone of excellent quality, which also occur beneath the next seam. The millstone-grit rises at many points from beneath the productive coal-field, and is separated from the old red-sandstone by the carboniferous limestone at Oreton ; hut In other parts It rests Immediately upon the sand stone. At Kuowlbury the Iron-ore is profitably worked. The coal-field of the Brown Cleat Hills lies a few miles north of the forma tion just described, and, like that, is surrounded on all sides by the old red-sandstooe, which here separates the coal-measures into two distinct elevations, known as the Close Bad and the Abdon Bart These two are the loftiest carboniferous tracts in Great Britain. The pits on the Abdon Barf are shallow. Those of the Cleo Bart' vary from 14 to 80 yards. Nearly all the best coal has been extracted. In this coal-field, as well as In that of the Titteratone Cleo IIill, there is abundant evidenoe of the tract having been Leaved up into Its present position by powerful forces acting from beneath, which have thrown the carbonaceous masses into separate troughs or basins.
The coal-field of Wyre, or Bewdley Forest, lies east of those just described, occupies the southessatern corner of the county, and extends into Worceatershire, the greater part of it lying within that county.
It has a length from north to south of about 20 miles, and a breadth in the Forest of Wyre of 5 or 6 miles. That portion of it lying in Shropshire and extending southward in a narrow zone from near Bridgenorth, is bounded on the west by the old red-sandstone of Chelmarsh.
The old red-sandstone system occupies a considerable part of the southern division of the county. It terminates on the north In the coal-field of Coalbrookdale, and on the east in that of the Forest of Wyre. On the west it la bounded in Corve-dalo by the upper Lud low rock of the Silurian system. At Ileiton's Bent, north of Ludlow, veins of copper-ore occur, whloh were formerly worked, but have been abandoned for upwards of a century. A large outlier of old red-sand stone, the principal part of which forms Clan Forest, occurs on the south-west of the county, and is separated from the great mass by wide intervening tracts of Silurian rock,. This outlier is nearly 100 square miles in superficial extent. Its western extremity reaches into Radnorshire.
The Silurian and Cambrian systems of rocks occupy all the southern division of the county lying west of a lino drawn from Ludlow to the Severn at Coalbrookdale, with the exception of Clun Forest. The Ludlow rocks rise from the old red-sandstone of Cores-dale Into eminences of 1000 or 1100 feet above the sea, exhibiting the sub diviaione of the formation, namely, the upper Ludlow rock, Aymestry limestone, and lower Ludlow rock. Nest of these, and separated by Hope dale, Is an escarpment extending from the valley of the Onny to coalbrookdale, called Wenlock-Edge, and composed of Wenlock Innestone. This is succeeded by Wenlock shale, composing the valley of the Caradoe, or Church Stratton Hills, which consist chiefly of different varieties of unbedded or amorphous trap, flanked on the east and west sides by Caradoc sandstone. On the north-eastern extremities of these Silurian rocks is an elevated and extensive tract of rocks of the Cambrian system, composing the Lougmynd and other mountains, with outbreaks of trap, and these are again succeeded by Caradoc sandstone, the altered and irregular ridge of the Stiperstone, and the trap-rocks of Shelve and Corndon. A vast expanse of Ludlow rocks then succeeds, and extends into Montgomeryshire. Among the trap and sandstones of Shelve and Corndon occur several metalliferous veins containing ores of lead, &c., of considerable value.