The Community lies partly within the boundary of the Geopark.  It comprises the town of Ystradgynlais together with those of Gurnos, Cwm Twrch Isaf and Cwm Twrch Uchaf and the smaller settlements of Cwmgiedd, Penrhos, Cae’r-Lan, Cae’r-bont and Aber-craf.  It falls within the county of Powys and was in the former county of Brecknockshire.

The lie of the land

Ystradgynlais Community ranges in height from about 60m near the confluence of the Tawe and the Twrch at SN 773084 to 544m at Disgwylfa (SN 815178).  Other notable summits include;

• un-named hill at 371m (SN 778151),
• un-named hill at 468m (SN784178) and
• Carreg Coegion at 474m (SN 791177). 

The Community is drained by the south/SW-ward flowing Afon Tawe and the southward flowing Afon Twrch and their tributaries, notably the Afon Giedd and Nant Cyw.

Solid rocks

The area is underlain by a variety of rocks from the Carboniferous Limestone in the north through the Twrch Sandstone and Bishopston Mudstone to the Coal Measures in the south.

Legacy of the Ice Ages

A glacier flowed down the Tawe valley.  Much of the area is plastered with glacial till.

Archaeology

Archaeological sites include cairns scattered across the unenclosed upland part of the Community.

There is some evidence of former limestone working.

Maps

Geology

Sheets 230 ‘Ammanford’ and 231 ‘Merthyr Tydfil’ of the British Geological Survey’s 1:50,000 map series of England and Wales give between them full coverage of the Community.  Two versions of each are available – one showing the bedrock (or ‘solid’) geology and the other showing the superficial deposits (or drift’ geology) which overlie the solid rocks.  BGS publishes a 'memoir' to accompany sheet 231.

General

The following Ordnance Survey maps cover the Geopark portion of the Community:

• Landranger sheet 160 'Brecon Beacons' (1:50,000 scale)
• Explorer sheet OL12 'Brecon Beacons National Park/Western area' (1:25,000 scale)

Public transport

Bus services operate along the A4067 road through the upper Swansea Valley and the A4221 Inter Valley Road from Glyn-neath. The nearest stations are at Neath and Merthyr Tydfil.

See Traveline Cymru for bus and train services including stops, timetables and route-planning information.

Links

The Sleeping Giant Foundation

Further reading

• 'The Iron Cradle' by Len Ley, published in 2005 by Glamorgan Press
• 'A Guide to the Industrial Archaeology of the Swansea Region' by Stephen Hughes & Paul Reynolds, revised edition published by RCAHMW in 1989, ISBN 1871184010
• 'The Brecon Forest Tramroads; the archaeology of an early railway system' by Stephen Hughes, published in 1990 by RCAHMW, ISBN 1871184053