Securing a place on the course

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1 Geological History of Wales: The Evolution of Wales and its Landscape Tutor: John Mason Course code: AE100E Dates: Saturday , and Securing a place on the course To secure a place on the course please ensure that you complete the University enrolment form and returning it signed with the fee. Please download the enrolment form from our website: For current availability of places please phone or or learning@aber.ac.uk Course overview This module builds on 'Geology - An Introduction'. It looks at the geological history of Wales and the landscape produced by hundreds of million years of natural processes such as volcanic eruptions, continental collisions and glacial erosion. The course is largely field-based and is focused on the district between Aberystwyth and Dolgellau. It involves short walks (maximum 4 km). The course is fully accredited by Aberystwyth University giving you the opportunity to study at Higher Education level 2, giving 10 credits which are excellent for professional development. The day-to-day itinerary is as follows: Outline of the Programme Field Trips You will need to be able to walk on steep and rocky ground at times and be reasonably physically fit. The meeting points for the field trips are all detailed below on the maps. Learners will be asked to car share on the field trips. Please note the dates of the field trips may change due to weather conditions. Please be aware that good weather is essential for field trips so dates may be re-arranged if severe conditions are forecast. We will set up an round robin in order to make such arrangements. Therefore these dates are provisional. Annotated maps covering rendezvous points are appended to this document. It is also highly recommended that you have 1:50,000 maps with you too: the Dolgellau (landranger 124) and Aberystwyth (landranger 135) sheets are the ones to have. Day 1: morning lecture at Machynlleth (venue to be confirmed), setting out the framework of the geological evolution of Wales. Beginning with the basics, we then spend the afternoon on the wild and beautiful section of the Cardigan Bay coast at Tonfanau, to the north of Tywyn. Here, participants will learn that most critical of skills - how to identify different rock-types with confidence. Tonfanau is an ideal venue for this because, thanks to the great ice-sheet that flowed down the western seaboard during the peak of the last ice-age, there is an extraordinary diversity

2 of different rock-types present among the boulders. They even include huge blocks of fossiliferous Middle Jurassic limestone, ripped up from the bed of Cardigan Bay and from a time in Earth history that is not represented by rocks on the Welsh mainland. Facilities in Machynlleth and, on the way and way back, at Tywyn. Day 2: Thus primed, we can now look at the rocks where they outcrop and learn to interpret their features. The Welsh landscape is highly variable, even over short distances, the variety being controlled by how different rock-types with differing properties respond to the forces of erosion, such as wind, water, frost, glacial ice and weathering. We go right back to the beginning, in this part of Wales at least, by visiting the Coed y Brenin forest, near Dolgellau. Here, we track the evolution of the early years of the geographical feature that was to dominate Wales from million years ago the marine Welsh Basin, with its variable fill of different types of sediment. We examine rocks deposited under highly energetic conditions and, at the other end of the scale, those deposited in deep water under conditions of marine anoxia, just as much an environmental hazard back then as it is now. Sedimentation in the Welsh Basin was at times disrupted by volcanic activity, a consequence of plate tectonics, and Coed y Brenin features plenty of evidence for magma making its way up through Earth's crust, in the form of sheets of intrusive rock. Many such sheets are horribly altered and mineralised, but we will go and look at two that retain original features, one of which was only rediscovered recently having been lost to science for 90 years and which in the 19 th Century was known as the magnificent Uralite porphyry. The two outcrops record the chemical evolution of a magma chamber beneath Earth's crust, that evolution producing magmas with different properties through time. We will finish off with a spectacular example of how different types of rocks, sedimentary and igneous, affect the type of scenery, at the famous Aerial Bridge. Facilities in Dolgellau, at Coed y Brenin Visitor Centre and in the village of Ganllwyd. Day 3: We take a leap forward in time to 438 million years ago, when rapid climate change and massextinction affected the planet over the boundary between the Ordovician and Silurian Periods. The events are recorded in the sedimentary rocks exposed at Carn Owen, in the hills to the north-east of Aberystwyth, and which also make up much of Mid-Wales. Here, too, we will see the all-tooblatant results of a continental collision, consider how such forces operate and learn how the effects of rock-deformation have affected the Welsh landscape. Following that collision, this part of Wales has remained land ever since. We will discuss how such a conclusion may be arrived at. Visiting a nearby lead-mine, we will then look at evidence for another important on-land phenomenon in landscape-development, deep weathering. There will also be the opportunity to collect samples of lead and copper ores, commodities that were widely sought-after in Wales and which, after everything that came before, have as a consequence left their own distinctive mark on the Welsh landscape. There are no facilities at these locations but in case of dire need, the village of Ponterwyd, a few miles down the road, has the usual range.

3 General information (what to bring) The work will be outdoors but there will be short indoor introductory sessions on the first day. The maximum number on the course will be 12. Clothing Food Students should provide themselves with adequate clothing for fieldwork in the range of weather to be expected in Wales at this time of the year i.e. warm and sunny; and cold and wet. Waterproofs and suitable footwear are essential. Please bring lunches, snacks and drinks with you. Equipment A small A5 field notebook will be provided. Please equip yourself with a pencil (ink isn t usually waterproof) and other writing materials. Increasingly digital cameras are found useful by some students to record details on field trips. A compass and a hand lens will be useful. For further details or questions about the course content please contact Lifelong Learning, Aberystwyth University on or learning@aber.ac.uk

4 MAPS Day One afternoon Tonfanau rendezvous Simply take the Aberdyfi/Tywyn (A493) road, either at Dyfi Bridge near Machynlleth or from the middle roundabout on the A470 Dolgellau by-pass. Either way, Tywyn is on the signpost. If coming from the Aberdyfi direction, continue through Tywyn and turn down L along the lane just after the modern bridge over the Dysinni after the village of Bryncrug. If coming from Dolgellau, head past Fairbourne and Llwyngwril and turn R in Rhoslefain. It's a winding lane so go steady. The parking is on the opposite side of the lane from the small but obvious Tonfanau railway station. No facilities here.

5 Day Two venue rendezvous 1) If coming from the south, travel to Machynlleth and on to Dolgellau. From Dolgellau head north along the A470 (signposted Porthmadog). You will come to a roundabout at Llanelltyd. Continue along the A470, through the village of Ganllwyd, over a substantial river-bridge and commence the long straight climb up out of the valley. Coed Y Brenin Visitor Centre is on the R, up a slanting road (turn-off is well-signposted). If coming from the north, go passt Trawsfynydd and start descending into the valley: the turning is on the L. Head for the car-park ( 3 for 3 hours). 2) Go back down the A470 into Ganllwyd and turn left onto minor road just here:

6 If you miss the turning, you can carry on into the village and turn around by the public loos on the L. In fact it's an easier turn coming out of the village. Follow the lane down and over a stone bridge. Straight ahead for ca. 0.5km until you see a pull-in on the R and NRW sign saying Pont Cae'n-y-Coed. Free parking here. We will move a second time but that will be in convoy, up to the top car-park (again free), at Tyddyn Gwladys. Day Three venue rendezvous The mountain road may be accessed from the A487 in Talybont or the A44 in Ponterwyd. Both are signposted Nant-y-Moch. Follow the road to a point overlooking the N end of the reservoir, where a track strikes off uphill. Ample roadside parking here.

7 We will go in convoy to the mine, which is a mile or two north of Carn Owen. It's up a dirt road just before the mountain road starts to descend to Talybont (OK to drive with care).