Late Palaeozoic Sedimentation, South Wales, UK
The course starts at Aberystwyth but is based mainly at Tenby, where it will end. Both towns are served by the national rail network. A wide range of siliciclastic and carbonate depositional environments are examined, dating from early Silurian to late Carboniferous. Almost the entire length of the classic Llandoverian turbiditic Aberystwyth Grits depositional tract is examined. At Pembrokeshire outcrops, fluvial sediments range from Devonian Old Red sandstone flash flood and braided stream deposits to Silesian incised valley fills. Lacustrine and classic deltaic successions are also excellently exposed and shallow marine siliciclastics are well represented. All siliciclastic outcrops are extremely rich in sedimentary structures. A Dinantian limestone succession is fairly complete and its variations provide a good basis for discussion in terms of modern carbonate environments. The rocks at each locality will be described within their regional contexts. Participants are encouraged to inspect most outcrops objectively to interpret and discuss the depositional settings.
- Borth / Clydach /Aberystwyth / Aberaeron / New Quay: Submarine fan turbidites of the Llandoverian Aberystwyth Grit Group.
- Freshwater West / West Angle Bay: Silurian overlain by Old Red Sandstone sequence with abundant palaeosols (caliches) in the Freshwater West Fm.; Ridgeway Conglomerate Fm.; Skrinkle Sandstone Fm., Carboniferous Lower Limestone Shales.
- Stackpole: Dinantian Stackpole Limestone Formation; palaeokarst.
- Tenby: Lower Carboniferous limestones (Oxwich Head Limestone, Hunts Bay Oolite, High Tor Limestone, Caswell Bay Mudstone, Gully Oolite, Black Rock Limestone).
- Ragwen Point: storm-dominated Namurian Twrch Sandstone disconformably overlying limestones of the Dinantian Oystermouth Formation.
- Telpyn Point: Telpyn Sandstone (local ‘Farewell Rock’). Namurian lowstand and transgressive systems tracts. Incised channel fill, liquefaction, palaeosol, coal seam. Contact between Numurian and Westphalian at the Gastrioceras subcrenatum marine band..
- East Amroth: Coal Measures including a Westphalian classic coarsening-up deltaic sequence incorporating the ‘Amroth slump’ and culminating in the Lady Frolic coal seam.
- West Amroth: Lower Westphalian Coal Measures containing the ankeritic Amroth Freshwater Limestone , Kilgetty Coal Seam, siderite concretions and liquefaction structures.
- Wiseman’s Bridge: multistorey channel stack with possible tidal influence
- Saundersfoot : Lady’s Cave Anticline; Stammer’s Veins (coal seams) and palaeovalley fill.
- Little Haven / Broad Haven: Westphalian A Coal measures with multistorey channels and anthracitic coals
- Nolton Haven: Upper Coal Measures Pennant Sandstone; low- and high-sinuosity streams with floodplain deposits and palaeosols.
Geoscientists and petroleum engineers who wish to examine a wide variety of depositional environments.
Basic understanding of Geology