Page:The South Staffordshire Coalfield - Joseph Beete Jukes - 1859.djvu/125

Rh Hill, and at the Hayes near the Lye Waste, 2 miles east of Stourbridge.

At a certain depth below this, is the Wenlock and Dudley limestone, which is locally called "White lime."

What is the exact thickness intermediate between these two limestones, or how far they were vertically apart at their period of deposition, we have no means of determining. In the only place where they both crop to the surface in one area, namely, at Sedgley Beacon and Hurst Hill, a fault runs between the two which has been traced on one side in the workings, but without arriving at any means of determining the amount of its "throw." I have, however, assumed 800 or 1,000 feet as the vertical distance between the limestones. This thickness enabled me to draw the sections, with the least amount of dislocation and disturbance, of which there was no decided evidence; but I feel by no means confident that that thickness ought not to be either diminished or increased.

There is no lithological distinction between the shale or bavin above the Dudley limestone and that below it, but the one above is assumed to belong to the Ludlow group, and that below it to the Wenlock.

Wenlock and Dudley rocks.— The Wenlock and Dudley limestone forms two bands of solid concretionary and flaggy limestone, with many calcareous nodules, concretions, and small flaggy beds, both between, above, and below them.

At Dudley, we have the two following sections of the limestone given in the Silurian System:—

At Hurst Hill, the beds are collectively thinner and the limestones closer together. At Mr. Bagnall's limestone pits at Dudley Port they found two bands of limestone,—upper, 27, and lower, 24 feet thick,—resting directly one on the other. At Mr. Giles's pit, however, according to Sir R. I. Murchison, the limestone worked was 21 feet thick, and they reached, by boring, another mass of limestone 150 feet below it. At Deepfield's, a little east of Hurst Hill, according to "Smith's Miner's Guide," they sank below the Coal-measures through 150 feet of blue rocky clunch, probably Silurian shale, and then came on limestone in about ten beds of nearly 3 feet each. In the neighbourhood of Walsall the Dudley and Wenlock limestone consists of—