One day field trip to South Wales

*Leader:*	Bob Leppard, Leppard Sedimentology
*Date:*	21 June 2008
*Logistics:*	Meet at the New Inn Amroth at 11.00am on Saturday 21 June. The trip will finish around 18.00 hrs. A pack lunch will be required. Attendees may also wish to visit on Sunday (by their own arrangement) Big Pit, the National Coal Museum (http://www.museumwales.ac.uk/en/bigpit/tour/).
*Cost:*	Free of charge - personal expenses will be required for food and return travel.
*To Book:*	Please complete the booking form and send to helen@pesgb.org.uk or fax 020 7408 2050. Booking deadline is Friday 13th June, maximum of 12 attendees.
*Important Information:*	This is a demanding trip as participants will be spending around 7 hrs either on the outcrop or walking to/from it. You will need to be physically fit and agile. There are also elements of risk in attending this trip: The cliffs are potentially dangerous and some of the section is located under overhangs. Hard hats should be worn on these sections although they will not protect you from a falling slab! There is a large section of boulder field which has to be traversed by hopping/jumping from one boulder to another. The boulders can be slippery after high tide. Towards the end of the trip we will be cut off by the tide and participants will have to climb over the point in order to reach the beach on the other side (this section is currently clear of sea weed although it can be slippery if it is raining). No individual section of the climb is more than c10 ft.

The geology
There is an almost complete sequence of the Middle Shale Member of the Namurian (Carboniferous) exposed within the cliff section between Marros and Amroth. This outcrop not only exhibits wave polished bases to the cliffs but also extensive areas of wave cut platform (depending upon sand cover) which are ideal for the detailed study of sedimentary structures.

This sequence comprises three major coarsening-upward sequences that commence with flooding surfaces. The first cycle illustrates the effects of wave motion on the sediment surface as the water depth decreases with shoreface progradation. Within the other two cycles there are numerous interesting sedimentary features and sequences, including load balls, trace fossils and marine bands.

The uppermost 30 m of this outcrop comprises the "Farewell Rock" which is an overall fining-upward fluvial channel fill sequence, the base of which depicts a low relief erosion surface that cuts into the underlying delta front sediments of Cycle 3 and is lined with an intraformational conglomerate. The sandstones above the erosion surface comprise a series of erosive based bedforms that are generally trough cross-bedded. The uppermost deposits are predominantly flat-bedded and current ripple-laminated, demonstrating an overall reduction in river discharge. Walking on bedding planes with the cliff section to one side provides a 3D section along the axis of this channel.

There will also be the opportunity to see sedimentation in action on the beach.