Loch lomond stadial glacier at Fan Hir, Mynydd Du (Brecon Beacons), South Wales: Critical evidence and palaeoclimatic implications
✍ Scribed by Richard A. Shakesby; John A. Matthews
- Book ID
- 102846312
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 969 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0072-1050
No coin nor oath required. For personal study only.
✦ Synopsis
The c. 1-2 km long, up to c. 25 m high ridge east of the almost north-south aligned Fan Hir scarp, Mynydd Du, South Wales has been regarded as a remarkable protalus rampart formed in the Loch Lomond Stadial (c. 11-10000 years BP). New data are presented which indicate that it is a moraine. The main points supporting this glacigenic origin are: its curved plan form at the lower, southern end; its scale and the ample depth for snow to glacier ice transformation; the presence of subsidiary ridges interpreted as recessional moraines; the exceptional rate of rockwall retreat required if it were a protalus rampart; and, most importantly, the presence in the ridge of matrix-supported abraded clasts, up to 20% of which are striated. Useful criteria for differentiating moraines and protalus ramparts are thereby proposed and a sound basis is provided for palaeoclimatic reconstruction. Palaeoclimatic inferences imply that the glacier owed its existence to the combined effect of a mean July temperature of c. 8.5"C and topographically enhanced accumulation, nearly half of which was from wind-blown snow.