Cymdeithas Daeareg Gogledd Cymru: Volume 35 North Wales Geology Association December 2003 The Chairman’s Bit Jonathan with first In the vogue of the lamentable advertising reach the capital of a foreign coun- for healthy products, ie. 96% FAT-FREE try than our own, but that's the way the news of a planned trips MILK, the October joint meeting with the cookie crumbles on the Celtic Fringe. I to Ireland and South Geologists' Association, South Wales guess that there have been times when Wales - and an exhor- Group was 93% MEMBER-FREE. Now, I New York was closer to Deganwy than tation to contact us think that that was a shame, because the six London is now, but we will let that pass. soon with expressions members who went were extremely im- Please contact Will Jones if you are inter- of interest . pressed by what was displayed to them, ested as soon as possible, and then we will know whether to or- ganise group travel or go individually and the scale of accommodation that must be found. An additional reason to travel next year may well be the fact that the An- nual Reunion of the Ge- ologists' Association will be held in Cardiff in No- vember 2004. This is a bold move following on from the first Reunion to be held outside London, in that it will be the first to be held outside Eng- land. The venue will be the National Museum of Wales, which will be holding exhibitions of international repute quite apart from the festivity of the Reunion itself. A collection of dwarfs was spotted in a South Wales open-cast coal mine….. There are also shops, theatres, galleries and INSIDE THIS and it was a fascinating contrast, and com- other entertainments on a scale un- ISSUE: parison, with the geology of the North with dreamed of in our rocky fastness. This is which we are more familiar. Yes, it is a an opportunity to be grasped, and soon - The Llangollen 2 long way to South Wales across (or travel and accommodation options are Field Trip around) the Wales-Brabant Massif, but invariably cheaper and more flexible in there is no gain without pain, even if you advance, and the further the better. 3 Hunting the elu- are walking with your dog around your lo- sive “pocket de- cal Quaternary exposures. The other thing that I forgot to mention is posits” of North that the Geologists' Association, South Wales However, your committee will continue to Wales Group are an extremely hospitable 6 offer excellent opportunities to study geol- bunch, and they will be doing their best Event Details ogy in the field, and in 2004 we hope to be to make everyone welcome. Please help Geology Diary 8 doing so in the Emerald Isle with a week- to make the event worth their consider- end itinerary based in or near to Dublin. It able effort. is incongruous that it will be quicker to Page 2 Volume 35 July 12 Sat , Castell THE CARBONIFEROUS NEAR LLANGOLLEN Dinas Bran and Asso- ciated Geology, Llan- Will Jones showed us the Carbonifer- conformity on the Lower Palaeozoic, gollen, a field trip with ous section near Llangollen. We through red beds deposited in a continental Will Jones worked our way up from the basal un- setting, to fully marine limestones. The pictures indicate the approximate level in the stratigraphy on the scarp, rather than the actual localities visited. Cross-bedded carbonate grain limestone indicates that dune scale sedimentary structures at least 2m high de- veloped - probably formed by large tidal currents. Reddened nodular beds (?soils) and red mud- stone (lagoon or playa lake?) intervals suggest the Carboniferous sea did at times retreat. The overlying section becomes increasingly calcareous upwards, until thick limestones with a range of shelly fossils show us that the tropical Carboniferous sea had finally drowned the old Palaeozoic hills in this area. The baking heat also made climbing The Carboniferous sediments on the unconformity up this gulley more like fieldwork in the consist of red mudstones and sandstones which tropics than in North Wales. were deposited in a terrestrial setting. Cymdeithas Daeareg Gogledd Cymru: North Wales Geology Association Page 3 SOME OLD RUINS NEAR LLANGOLLEN…. Castell Dinas Bran, which sits on a hill of Silurian shales and calcareous sandstones, has commanding views of the Dee Valley and Llangollen town. From the vantage point of Castell Dinas Bran, Will Jones points out abandoned courses of the River Dee. Rock dug from near the crest of the hill was used to build the castle walls, whilst at the same time creating a defensive ditch. North Wales: Geology On Our Doorstep Page 4 Volume 35 Oct 10-12 Fri pm., SOUTH WALES: DAY ONE—THE CARBONIFEROUS Sat & Sun, Geology of South Wales , a field trip led by Geraint Owen, Alan Cuthbertson and Stephen Howe Glacial deposits Geraint Owen led much of the Saturday and here shows us Proof that glaciers reached South Wales: fossiliferous intervals within the Carboniferous Limestone. poorly structured boulder clay and other Pleistocene sediments overlying bedded Pausing for breath/ examining an out- The “disturbance” - here Carboniferous Limestone is tightly crop whilst scrambling up to the folded and faulted along the trend of the Vale of Neath fault. “disturbed” Carboniferous. Cymdeithas Daeareg Gogledd Cymru: North Wales Geology Association Page 5 SOUTH WALES: The plan for the weekend would be to see the representative geology and landscape features of central South Wales, including: Upper Car- boniferous Coal Measures of the South Wales Coalfield; Carbonifer- ous Limestone and Namurian (Millstone Grit) of the Coalfield mar- gin; and Mesozoic rocks of the Vale of Glamorgan. The geology will be related to landscape, which is controlled by both lithology and structural features, and to the resources of the area, including both present and past exploitation. Localities to be visited will include a working opencast coal site; sites along the Swansea Valley or Vale of Neath Disturbances; sites in the "waterfall country" of the upper Vale of Neath; and coastal sections in the east of the Vale of Glamorgan, where Triassic desert deposits and fossiliferous marine Lower Jurassic deposits overlie eroded Palaeozoic rocks at a spectacular unconformity. The provisional plan would be: Saturday: Nant Helen opencast site (Allan Cuthbertson); Cribarth, Swansea One of many steep faults cutting the Triassic to Jurassic section Alternating beds of pale carbonate and dark, organic-rich mudstones in the Upper Triassic and Lowermost Jurassic. Is Will Jones (hands and knees) expressing our appreciation to North Wales: Steve Howe (centre) for leading an excellent day in the field? Geology On Our Doorstep Page 6 Volume 35 DINOSAURS OF SOUTH WALES Note the 3 clawed toes. A classic unconformity: dipping Carboniferous Limestone (Will Jones) capped by disorganised debris (Jonathan Wil- kins) which is overlain by flat-lying Triassic red beds with footprints of primitive dinosaurs (Peter Appleton). Probably a different species AGM, LLANDUDNO 2.00 pm to 5.00 pm on Saturday 1. SUBSCRIPTION RATES FOR 2004 31st January 2004 at either Robert- (these are agreed at the start of each son Research or the Great Orme year) Copper Mine, Llandudno The following individuals are prepared to stand for re-election to the positions indi- AGM AGENDA ITEMS cated. 1. CHAIRMANS REPORT Chairman & (a summary of our activities in 2003 Membership,……….Jonathan Wilkins and plans for the coming year) Wrexham Meetings ……. ….…vacant 1. TREASURER'S REPORT Other Meetings……….....Will Jones If in doubt, (a report on finances for the year Secretary,……………..Susan Brookes 2003) Treasurer,…………...Gareth Williams contact us, 1. ELECTION OF OFFICERS FOR Deputy Chairman & 2004 Newsletter …………….Rob Crossley (we don’t bite...) (section 5. of the constitution - be- low - is relevant to election of offi- We are unanimous in our wish to encour- cers) age new members to join the committee. Page 7 Volume 35 AGM (CONT.) Please feel free to contact any committee Meeting during January at which sub- member to find out what is involved, and scription rates will be set for the com- send your nominations by 27th December ing year. to the association Secretary: • The Treasurer will present financial accounts for the year at the Annual Susan Brookes General Meeting. 9 Pencae • Accounts will be audited by at least Llandegfan one other society member and may be Menai Bridge inspected by any member upon writ- LL59 5TT ten request. YNYS MON • Business meetings will be held at least twice each year or as often as CONSTITUTION necessary. Minutes will be circulated as required. 1. NAME: • If the society shall cease to exist then • The society shall be known as: any balance of funds remaining after Cymdeithas Daeareg Gogledd Cymru - settlement of accounts shall be trans- North Wales Geology Association ferred to the Geologists' Association. 1. OBJECTIVES: 1. OFFICERS: The aims of the society shall be: • The society's business shall be exe- • To promote the study and knowledge cuted by a committee of the following of Earth Science, with particular ref- minimum of elected officers who erence to North Wales must also be members of the society: • To convene indoor and field meet- Chairman, Secretary, Treasurer, ings on topics relating to geology Publicity, Meetings. and geomorphology • Any number of members may be co- • To assist in the teaching of Earth Sci- opted as required for tasks or duties ence wherever appropriate as they arise. • To maintain and publicise a pool of • Officers shall serve for one year after expertise which can be drawn upon which they will tender their resigna- when required. tion at the Annual General Meeting. They may offer to stand for re- • To correspond and associate with election immediately.