Long excursion to the Berwyns. July 31st to August 7th, 1908 - Geologists' Association excursion

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Long excursion to the Berwyns. July 31st to August 7th, 1908 - Geologists' Association excursion (Transcription of Geologists' Association Circular No. 97. Session 1907–1908)[edit]

DIRECTOR : J. LOMAS, F.G.S.

EXCURSION SECRETARY : H. EIDNER, 78, Gladstone Road, Watford.

RAILWAY ARRANGEMENTS.—The official party will travel on Thursday, July 30th, by express leaving Paddington (G.W.R.) at 2.15 p.m., arriving Oswestry 6.32. Tea and light refreshments served on train. Dinner at the Wynnstay Hotel, 7 p.m. If not less than ten apply beforehand special cheap return tickets will be issued for 18s. 3d., available until Monday, August 10th. Early application is requested.

HOTEL ARRANGEMENTS.—The headquarters will be at the Wynnstay Hotel, Oswestry. Tariff 8s. 6d. per day, including bed, attendance, breakfast, sandwiches for lunch, and dinner. All applications for rooms should be made without delay to the proprietor of the Wynnstay Hotel, stating that it is in connection with the Geologists' Association party. If more apply than can be accommodated at the Wynnstay, arrangements have been made for them to be quartered at the Queen's Hotel, but they will dine with the rest of the party at the Wynnstay in the evening. Any who stay at the Queen's Hotel will obtain their sandwiches there in the morning.

GENERAL ARRANGEMENTS.—The Secretary for the Excursion, Mr. Kidner, should be informed immediately application is made to the Hotel, and members should state definitely on what days they desire to be included in the arrangements for drives and teas. The Association's official luggage labels should be used, and a stamped addressed envelope enclosed for a reply.

Friday, July 31st.

Breakfast 7 a.m.

Leave Oswestry (G.W.R.) at 8 a.m. for Llangollen ; special return fare 1s. 6d.

Take lunch. Arrive Llangollen 8.52.

After arrival time will be given to visit Plas Newydd and other objects of interest.

Meet on the Dee Bridge, Llangollen, 10 o'clock.

The town lies on Shales of Wenlock age. Good exposures are seen in the river bed, in quarries about a mile west of the town, on Castell Dinas Bran, and in other places. Well preserved fossils can be collected.

At Divren Uchaf Carboniferous basement beds rest unconformably on the Silurian. On following the Carboniferous limestone up the scarp of the Eglvvyseg rocks a complete sequence can be obtained, and if continued eastwards the easterly dip brings up successively newer beds until the Coal Measures are reached just beyond Trevor.

The accompanying section* shows the sequence of the rocks and their lithological characters (see Fig. 1). Palmontologically the lowest beds at Tan-y-graig are the equivalents of the D1 beds of Dr. Vaughan's classification. D2 comes in just above the thick massive limestone on the Western Cliff, and is continued in receding scarps into sandy limestones, sandstones, conglomerates, and cherts, which represent D3 and higher beds.

The route (total walking distance 6 miles) will be up the escarpment at Tan-ygraig, Trevor Rocks, Bronheulog Quarries, and by Cefn-y-Fedw to Trevor Station. Tea at Australian Arms, Trevor.

Train leaves 5.48 ; arrive Oswestry 6.41. Dinner at Wynnstay Hotel 7.55 p.m.

Saturday, August 1st.

Breakfast, 8 a.m. Drive (9.15 a.m.) to Selattyn. Take lunch. Carboniferous Limestone D2 and overlying Conglomerates D3 are well exposed in quarries at Craignant. Walk past Offa's Dyke, and up a short hill to water-shed dividing the Dee and Severn drainages. At the summit, about 1,150 ft. above sea level, is a glacial overflow channel.

Meet carriages at summit, and drive to Llansantffraid-Glyn Ceiriog, passing over Bala beds and Tarannon shales.

Leave carriages and walk to Cae Diecws, fossiliferous Bala shales and limestone on the way. At Cae Diecws very fine exposures of igneous rocks; Rhyolites and tuffs.

Descend into the valley and walk along tram line to Hendre Quarry. Here an intrusive Keratophyre is quarried, and the Bala beds above and below have been turned into spotted slates.

Carriages meet party at Hendre and drive to Glyn. On the way other igneous rocks are well exposed, and will be visited if time permits.

Tea at Glyn Valley Hotel, 1s.

Drive to Oswestry through the picturesque Ceiriog Valley and Chirk. Cost of drive 3s. Dinner at Wynnstay Hotel, 7 p.m.

Monday, August 3rd.

Breakfast, 8 a.m. Drive (9.15 a.m.) to Allanson's Quarry, near Oswestry Racecourse. Take lunch. Decalcified limestones and cherts with D3 fauna. To the north of the Racecourse there are great mounds of glacial gravels. The Gloppa pit, 1,130 ft. above sea level, will be visited, from which a rich fauna has been obtained by Mr. A. C. Nicholson (Quart. Y ourn. Geol. Soc.. vol. xlviii, Feb. 1892, p. 86). The boulders are mainly of northern origin. Eskdale Granite is found in profusion. . Copied by permission of Miss Morton from "The Carboniferous Limestone and Cefn-y-Fedw Sandstone of the Country between Llanymynech and Minera, North Wales," by George H. Morton, F.G.S., F.R.G.S.I., p. 51. D. Bogue, London, 1879.

Erratics also occur from other localities in the Lake District and South Scotland, whilst Ganister Coal, Trias Sandstones, Limestones, Cherts, &c., have evidently been derived from the intervening country, From Gloppa drive to Llawnt. On the way a fine view is obtained of Offa's Dyke. (See Fig. 2).

The Carboniferous limestone at Llawnt is seen resting on Bala shales. The limestone contains many bands of black marl with concretions, and faulting has produced some curious effects in the marls. Continue drive through Llansilin to Glascoed, where Hornblende Andesite is quarried. Light refreshments at Llawnt or Llansilin. Tea at Trefinen, 1s. Treflach Wood and Nant Mawr quarries will be visited, and then drive to Oswestry through Porth-y-Waen,

Cost of drive 3s. Dinner at Wynnstay Hotel, 7 pm.

Tuesday, August 4th.

Breakfast 8 a.m. Take lunch. Drive, 9.55 a.m., to Llanrhaiadr-yn-Mochnant.

Examine fossiliferous slates near Llangedwyn. Visit Pistyll Rhaiadr. The water falls 250 ft. over a bed of Felsite. About 14 miles up the valley is Llyn-llyn-caws, a mountain tarn at the base of a beautiful cirque.

If time permit Cader Berwyn will be climbed, from the summit of which fine views can be obtained over Snowdonia, Plinlimmon, the Cheshire and Shropshire plains, the Wrekin, &c.

Return to Llanrhaiadr. Tea at Wynnstay Arms 1s. Cost of drive 3s. Dinner at Wynnstay Hotel, 7 p.m.

Wednesday, August 5th.

Breakfast 8 a.m. Take lunch. Drive (9.13 a.m.) by way of Llanrhaiadr to Craig-y-Glyn, where there are good exposures of Llandeilo Limestone—very fossiliferous—associated with igneous rocks. Continue drive to Maen-Gwynedd slate quarries, where igneous intrusions can be seen which have baked the rocks into spotted slates. Return to Llanrhaiadr. Tea at Wynnstay Arms, 1s.

Drive back to Oswestry. Cost of drive 3s. Dinner at Wynnstay Hotel, 7 p.m.

Thursday, August 6th.

Breakfast, 7.30. Take lunch. Leave Cambrian Station, 8.30 a.m. for Llangynog. Special return fare 2s. Visit fine exposure of spherulitic Rhyolite, which may be a volcanic neck. Examine slate quarries and igneous rocks of Craig Rhiwarth or walk to Milltir Gerig to see dolerite dyke and Bala limestone. Tea (9d.) at New Inn, Llangynog. Total walking distance 8 miles. Return from Llangynog Station, 3.30 ; arrive Oswestry 7 p.m. Dinner at Wynnstay Hotel, 7.30 p.m.

Friday, August 7th.

Breakfast, 8 a.m. Take lunch. At 9.30 a.m. walk over Sweeny Mountain to Porth-y-Waen, crossing the Carboniferous succession from Coal Measures to Carboniferous Limestone.

Examine quarries in igneous rocks at Llanyblodwell. Visit the extensive limestone quarries (See Fig. 3). Fine view over Shropshire. Walking distance about 8 miles. Tea (9d) at Lion Hotel, Llanymynech. Return to Oswestry from Llanymynech, 4.27 train ; arrive Oswestry 4.45. Single fare, 6d. Examine the Glacial deposits at Old Oswestry before dinner, or visit the Filter Beds of the Liverpool Corporation Water Supply. Dinner at Wynnstay Hotel, 6.30.

REFERENCES.

1850-55. Maps. Geological Survey. Sheet 74, N.E., S.E., S.W.

1827. YATES, Rev. J.—" Observations on the Structure of the Border Country of Salop and North Wales, and of some Detached Groups of Transition Rocks in the Midland Counties." Trans. Geol. Soc., Ser. 2, vol.

1845. SEDGWICK, Prof.—" On the Older Palaeozoic Rocks of North Wales." Quart. ,Journ. Geol. Soc., No. i, Feb. 1845.

1860. DAVIES, D. C.—"On the Discovery of Fossils in the Millstone Grit near Oswestry." Report Oswestry and Welshpool Nat. Field Club, 1860.

1881. RAMSAY.—"Geology of North Wales." Mem. Geol. Survey, vol. iii, 2nd edit.

1889. MORTON, G. H.—"The Carboniferous Limestone and Cefn-y-Fedw Sandstone of the Country between Llanymynech and Minera." (D. Bogue, London, 2889).

1892. NICHOLSON, A. C.—"On High-level Glacial Gravels at Gloppa." Quart. ,Journ. Geol. Soc., Feb. 1892, vol. xlviii.

1897. GIEKIE, Sir A.—"The Ancient Volcanoes of Great Britain." vol. 1.

1902. MOORE, C. C.—"The Study of the Volume Composition of Rocks." Part ii, " The Examination of an Igneous Intrusion." Proc. Liverpool Geol. Soc. 2902-03, Pres. Address.

1903. COPE, T. H. and LOMAS, J.—"On the Igneous Rocks of the Berwyns." Brit. Assoc. Report, 1903.

1904. JEVON, H. STANLEY.—"Note on the Keratophyres of the Breidden and Berwyn Hills." Geol. Mag., Decade v, vol. xi, No. I, Jan., 1904.

1906. HIND, Dr. WHEETON, and STOBBS, J. T.—"The Carboniferous Succession below the Coal Measures in Shropshire, Denbighshire, and Flintshire." Geol. Mag.. Sept.-Nov., 1906.

1908. GROOM, Dr. THEODORE, and LAKE, PHILIP.—"The Bala and Llandovery Rocks of Glyn Ceiriog (North Wales)." Abst. Proc. Geol. Soc. of London, No. 863. May 28th, 1908.

The TIMES OF TRAINS are taken from the current time-table ; Members should check them when the new time-tables are published. In case of alteration the train will be that nearest to the one given.

Whenever SPECIAL FARES are quoted, Members should meet the Excursion Secretary at the booking office at least fifteen minutes before departure of train.

Members who PROPOSE JOINING EXCURSIONS after departure from the Railway Station in London must notify their intention to the Excursion Secretary beforehand, if they desire to be included in any arrangements for tea or carriages. In all such cases it is important that an addressed post-card should be enclosed for acknowledgment, and this acknowledgment should be brought on the Excursion for production, should occasion arise.

ALFRED C. YOUNG, F.C.S., Sec. (Excursions), 17, Vicar's Hill, Lamborn, S.E.