SPELEOTHEM DATES FROM THE UPPER SWANSEA VALLEY, SOUTH WALES, UK

Uranium-thorium dates have been obtained from speleothems collected from a cave system in the upper Swansea Valley, South Wales, (Ogof Ffynnon Ddu, The Cave of the Black Well). The cave is located in a glaciated valley with the present spring resurgence at an elevation of 182 m amsl. The Brecon Beacons nearby rise to nearly 900 m. During the last and previous glacials the area was covered with ice.

The cave has over 40 km of mapped passages, a vertical extent of > 300 m, and three extensive abandoned tiers at levels of about 420 m, 330 m and 220 m above sea level. Samples were collected from the two upper abandoned tiers because of extensive silty (420 m level) and sandy (330 m level) deposits on the floors of both tiers that could be of significance in understanding the geomorphological history of the cave.

Attempts were made to collect some samples with regards to their geological significance in particular cave passages. Many passages have dissolution notches in walls that sometimes relate to dateable deposits remaining on the opposite passage walls that are a record of flooding events. It should be acknowledged that flooding history would have been complicated and much of the record may be buried or missing. Nevertheless, the remaining sediments could be most interesting and informative.

The ages span a range of 190 ka – 4.6 ka, cluster somewhat, and relate to the Wolstonian glacial (or interstadials within) the last (Ipswichian) interglacial, and interstadials within the Devensian glaciation (Upton Warren interstadial) and the Flandrian/Holocene. No growth was recorded during the last glacial (MIS 2). The distribution of ages generally follow that described by (Christopher et al., 1996; Gordon et al, 1989) in the same and nearby caves and from elsewhere in the United Kingdom (Gascoyne et al., 1983).