April 9, 1915. THE COLLIERY GUARDIAN 755 PONTYPRIDD. of N?3-Llantwit ELY VALLEY. LLANTWIT -FARJTRE. m Vp<7 LI antwit, -NN? 3 Lian twit Pit Top . iJprandddy Pit Top A?1 Rhondda, N?2 Rhondda,. M3 Rhondda,. £ g s £ Feet I. Cetn -glas t? & S' I T11E HARRI S. Nynv ddid nyn v-3 Oo § JV? 1 Rhorodda, N?3 RJiondda, Ml Rhondda I! Danran^Mu. Jour Fixt ,Sia>'Teet. Nave-Feet • AT 2 Rhonddoi. NP2 Rhondda .N?3Ji,hjorald(v Pit Bottom, ii, £ A3 Nino- Fcfit,, Fig. 5.—Diagrammatic Sections to Illustrate the Variations of Thickness. South Rhondda Colliery.—For the section of the measures which were proved by the pit and drift of this colliery the writer is indebted to Mr. W. W. Hood. The measures below the Rock-fawr were proved by a drift. The Rock-fawr Seam.—The Survey authorities state in the Memoirs, part IV., p. 38, that they take the Rock- fawr “to be the No. 2 Rhondda seam and the base of the Pennant series,” and on p. 79 of the same Memoir it is said:— The shaft of the South Rhondda Colliery at Llanbad proves the Rock-fawr as No. 2 Rhondda at 13 yards depth, and the No. 3 Rhondda seam at 98 yards. That No 2 Rhondda was proved in the shaft at 13 yds. depth, the writer fully admits, Lut that it is the Rock-fawr is in his opinion quite untenable. The seam at 13 yards in the pit is without doubt the Malthouse seam, w hi th ci ops out near the summit of Mynydd-y- gaer and can be traced for several miles. This seam— or the Rock-fach about 40 yards lower—was stated to be No. 2 Rhondda in the writer’s 1876 paper, and the Survey authorities have taken the Malthouse seam as No. 2 Rhondda, altering its name to Rock-fawr. Within the last six months the writer has again investigated the Mynydd-y-gaer district, and is con- firmed in his opinion that the seam which has always been known as the Rock-fawr, and of late years has been worked in Meiros, South Rhondda, and Bryn- chwyth Collieries, is No. 3 Rhondda. The chief officials of these collieries have expressed to the writer their concurrence; in fact, Mr. W. W. Hood wrote to the writer during the year 1914 saying:— The No. 2 seam is not the Rock-fawr, as that seam is, in my opinion, the No. 3, as you hold it is. These correlations harmonise the sequence of the seams in Pencoed district with the sequence at Tondu, but the measures expand in going westward to Tondu. § [Again, the d'stances between Nos. 2 and 3 Rhondda and the Pentre seam in the Rhondda Valley and at Gilfach-goch agree so closely with the distances between No. 2 Rhonda and the Rock-fawr, and Victoria “ Lantern ” in the Pencoed Collieries that they afford additional support to the correlation. One other fact may be mentioned: At Brynmenin and also at Tondu the Rock-fawr seam is reported to have in some areas a band of “ Lantern ” or cannel coal on the top of the seam. The writer, however, has not been able to find one instance in the entire coalfield of a band of cannel coal occurring on the top of No. 2 Rhonda seam. On the other hand, No. 3 Rhondda has such a band in the Rhondda Valley, Gilfach-goch, Penrhiwfer, Coed-Ely, and at each of the Pencoed collieries ; also for the Ogmore and Garw valleys the same statement holds good, and the writer submits that the facts stated amount to a practical proof that the Rock-fawr seam of Pencoed, Brynmenin and Tondu is No. 3 Rhondda. It may be stated that the band of cannel is imper- sistent, it thins down and disappears over considerable aieas, but comes in again. Coed-Ely Colliery.—Since Part I. was published the pits of this colliery have been completed, and the writer is indebted to Mr. David Hannah and Mr. F. Llewellyn Jacob for the section. The information which it affords gives another illustration of the remarkable variations that occur in the thickness of the Pennant, of which still further instances will be given in the sequel. In the writer's paper of 1903, entitled “ Notes on the South Trough of the Coal Field, East Glamorgan,” he gave the results of his measurement of the Pennant thickness—between No. 2 Rhondda seam in Collena Colliery and No. 3 Lian twit, or Tydu, seam—at the syncline a little to the south of Ton-yr-efail, which amounted to 520 yds. At Coed-Ely Pits, about a mile to the south of Ton- yr-efail, the workings in Nos. 2 and 3 Rhondda seams have not yet extended far enough to be vertically beneath the outcrop of the Tydu seam at Tylcha-fach, but Mr. F. Llewellyn Jacob informed the writer that they have got sufficiently near to that outcrop to enable an approximate estimate to be made, and that the vertical distance between No. 2 Rhondda and the Tydu seam might be taken as 396 yards. This distance is 124 yards less than the writer’s measurement at Ton- yr-efail, but he still considers that measurement to be a close approximation to actuality at the syncline, for the workings in Collena Colliery proved two-thirds of the 520 yards, and the surface exposures of the Pennant enabled good measurements to be taken over the remaining distance. From this it will appear that there is an attenuation in the Pennant from the syncline to Coed-Ely pits of probably 100 yards, unless a down- throw fault to the north-east exists between the colliery workings and the Tydu crop at Tylcha-fach. The new pits of the Great Western Colliery Company at Cwm, Llantwit-fardre, prove the Pennant thickness there to be 525 yards, or 5 yards more than the above measurement at Ton-yr-efail syncline, consequently between the Cwm pits and Coed-Ely there must also be an attenuation in the Pennant of 129 yards, and the Pennant thickness in the lower part of the Ely Valley will consequently be less than in any other area of the South Trough. The thickness of the lower measures at Coed-Ely cannot be stated with accuracy. The seam at 666 yards 1 ft. 6 in. in the pit is considered to be the Six-feet, but the Nine-feet and still lower seams do not prove in the pit with their normal thickness, and cannot be identified with certainty. Taking the seam at 666 yards 1 ft. 6 in. to be the Six-feet, its distance beneath No. 2 Rhondda is 380 yards, and if to this 90 yards be added for the normal farther distance to the bottom seam it will give 470 yards as the thickness of the Lower measures there. Cwm Colliery : Margaret Pit.—For the section of this new and important colliery the writer is indebted to Mr. Hugh Bramwell, under whose direction the shafts were sunk. The Margaret pit, started 22 yards beneath the horizon of No. 3 Llantwit seam and No. 2 Rhondda, was intersected at 503 yards, thus proving the Pennant thickness there to be 525 yards as above stated. This thickness is less than in the Pontypridd area two miles to the north, and it forms a striking exception to the general rule that the Pennant thickness expands to the south and west, but the consideration of this point will be more conveniently illustrated a little later on. The lower measures also are thinner in this pit than at the Great Western Colliery to the north, the thickness between No. 2 Rhondda and the Nine-feet being 296 yards at Margaret Pit (inclusive of 8 yards cut out by a fault), and 337 yards at the Great Western Colliery, a southward attenuation of 41 yards in 2 miles. In fact the lower measures are thinner at Cwm Colliery than at any other position in the South Crop. (To be continued).