The Geology of the South Wales Coal-Field (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1904 edition. Excerpt: ...of the British Rhondda Colliery give a particularly instructive example, showing how pressure has been relieved partly by folding, partly by overthrusting. In the section forming Fig. 3, the coal-seams are represented by continuous lines where they have been proved. It will be observed that the Nine-feet Seam bends so sharply down between sixteen and seventeen chains from the mouth of the drift that it was impracticable to follow it, while the Four-feet Vein shows this fold in a much modified form, but accommodates itself to a reduced space by repeated overthrusting. The strata are overthrust from the south on the north side of the trough, but from the north on the south side. Cwm-gwrach is a deep ravine in the lower measures, leading down to Glyn Neath Station. The Rosser Veins crop east of the Infant School, and the Bluers Vein further up the ravine, the section of the latter according to Mr. Morgan W. Davies being as follows: --Bluers Vein, Cum, Gwrach. Ft. In. Rashes--"-10 Bast 0 4 Coal 2 0 Parting 0 2 Coal 0 9 Vale of Neath (continued). By W. Gibson. On the east side of the Neath Valley the numerous streams and deep channels flowing down from the Pennant escarpment lay open the Lower Coal Series from the horizon of No. 2 Rhondda down to the Enoch Vein. The strata between No. 1 Rhondda and the Aberdare Six-feet Seam are penetrated by the shafts of the Cwm Clydach Colliery, Resolven (Vertical Sections, Sheet 85, No. 12.) The best exposures of the lower portion of the series are afforded by tht numerous streamlets issuing from the foot of Craig-isaf. The strata are thrown into a number of small but sharp folds, which, however, failed to produce any effect upon the thick beds of grit. Cwm yr Argoed, a little north of Blaen-gwrach, ...