Cymdeithas Daeareg Gogledd Cymru
North Wales Geology Association
Programme :
at a
Which way to meetings?

Sunday July 29th 2018
Field Meeting: Pen yr Henblas Quarry, Halkyn
Leader: Chris Twigg

Sunday August 19th 2018
Field Meeting: Benllech, Red Wharf Bay
Leader: Jonathan Wilkins

Wednesday October 10th 2018
Multibeam sonar: Revealing the hidden marine geology of Wales.
Speaker: Michael Roberts, CAMS, Bangor University

Wednesday December 5th 2018
Annual Members' Meeting

Saturday 26th January 2019
Annual General Meeting

Wednesday February 20th 2019
Bronze-age Copper

Wednesday March 20th 2019
Greenlandic memories

Wednesday October 9th 2019
Tides and sea levels – through time and space

Wednesday December 11th 2019
Selling sea shells on the sea shore

July 29th 2018
Field Meeting:
Pen yr Henblas Quarry
Leader: Chris Twigg and Tom Hughes, NEWRIGS
Based on the Pen yr Henblas Quarry, Pentre Halkyn

This field trip is a follow up to Tom Hughes short article in Newsletter 97, and to the brief "taster" visit a number of us made to the western quarry high wall last summer.

Pen yr Henblas Quarry"Pen yr Henblas quarry is of regional geological importance because it has excellent exposures of the Lower Carboniferous Pentre Chert and Cefn Mawr Formations. There is also exposure of the regional unconformity between the Pentre Chert and the underlying Cefn Mawr Formation".

There is a lot to see here, in spectacular exposure. The site is an abandoned quarry, with open public access, and opportunity to park nearby. In the quarry itself, there are the usual precipitous walls, spoil heaps etc, but it is only a short walk from the car park area, into the quarry, and this should not be considered an arduous trekking visit.

Please note hammering should only limited to breaking up existing fallen debris (there is plenty of it). As well as the usual brachiopods and corals there have been a number of sharks' teeth, and a coelacanth jaw recovered from this quarry.
News hot off the press: Chris Twigg has promised to bring along the coelacanth jaw!

Once we have finished fossicking in the quarry, there are plenty of interesting outcrops of Carboniferous Limestone, and old mining archaeology in the surrounding landscape to walk about in.

Please contact Keith Nicholls to register your interest.

Image ©Dave Dunford. #4418887

August 19th 2018
Field Meeting:
Benllech, Red Wharf Bay/Traeth Coch
Leader: Jonathan Wilkins
Based on the upper shore of Red Wharf Bay, nr Benllech, Anglesey

Carboniferous Karstification

Trwyn Dwlban

This meeting is designed to appeal to members who do not relish arduous upland or subterranean rock exposures; instead we take to the traditional Welsh seaside for a look at the Carboniferous Limestone of south-eastern Anglesey.

Cyclic sedimentation is well-known in this formation, where thick beds of limestone are interrupted periodically by mudstone beds representing deeper water. However, emergence of the limestone surface due to lowered sea level allowed the development of a Carboniferous karst surface which has been exposed to modern view as a result of erosion. Subsequent to the development of the karst surface, renewed sedimentation as the relative sea-level rose once more resulted in sandstones being deposited into the features of the karst surface. The modern exposure of these features include in-filled pipes and isolated sandstone columns where limestone has eroded from around them. It is claimed that these exposures are unique in the British Carboniferous!

Join us for a very gentle rocky-ramble, whose maximum elevation is around 5 metres and whose maximum length is around 1000 metres, depending upon where you park your vehicle. Full facilities are available in nearby Benllech, and we have checked that low tide is at mid-day.

Please contact Jonathan Wilkins by email or telephone to register your interest.

Image ©Jonathan Wilkins (not Geograph this time).

October 10th 2018
Multibeam sonar: Revealing the hidden marine geology of Wales.
Speaker: Dr Michael Roberts, CAMS, Bangor University
Meeting Room, Pensychnant, Conwy.
Location details and map: Contact/Find

Meeting to commence at 19:30h

skerries sonar image For the last six years a team of researchers and technical support staff from Bangor University have been undertaking numerous surveys of the marine environment off the coast of Wales. The data and resultant outputs are now providing fascinating new insights on marine processes operating over a range of spatial and temporal scales. This talk will include images and 3-d models illustrating a range of marine geological features including previously unseen and unknown rock outcrops and sedimentary bedforms.

It is hoped that this informal presentation will be of great interest to the audience and stimulate further discussion on how best these new insights can contribute to better understanding the marine geology of Wales and geological/sedimentological processes in general.

Dr Michael Roberts is R&D Manager in the Centre for Applied Marine Studies at Bangor..

December 5th 2018
Annual Members' Meeting.
Speakers: Richard Birch, Gary Eisenhauer, Jonathan Wilkins
Meeting Room, Pensychnant, Conwy.
Location details and map: Contact/Find

Meeting to commence at 19:30h
We are pleased to announce that extra refreshments of a potentially seasonal nature will be available to help the party swing. skerries sonar image

Gary Eisenhauer: Cwmorthin Quarry 2018
A video presentation gathered at this year's field meeting in Cwmorthin Quarry. Inaccessible to some, and not the 'cup-of-tea' of many members, Gary thought that this might be a suitable introduction to the dark and esoteric world of slate-working.

Richard Birch: Trilobites & their Relatives
A short, fascinating film on the 2017 conference of the same name in Tallinn, Estonia. Filmed in high-definition, it highlights a couple of the most interesting presentations, and explores this beautiful city and country, including a few of its birds, wildflowers and Ordovician marine reefs.

Rob Crossley: Lesotho kimberlites & diamonds
A unique opportunity to see inside the ultra-secure world of kimberlite-pipe diamond mining. And why we thought Penmaenmawr quarry might be able to teach them a thing or two.....

Jonathan Wilkins: Geology and Seaweed
More light-hearted than the accompanying films, but with a real science core, this presentation highlights the complex and intriguing links which can be discovered in the coastal ecology of western Ireland. Jonathan has not yet mastered the moving image, so only static shots will be provided. Health-warning: contains images of rocks, seaweed and tractors.

26th January 2019
Speaker: Dr Cathy Hollis, University of Manchester
Location: Antioch, Capel Salem, Abergele Road, COLWYN BAY. LL29 7PA

Annual General Meeting commences 10:00h
Refreshments at 11:00h
Lecture to commence at 11:30h

The Great Orme: an ancient carbonate platform with hidden treasures
skerries sonar image The Great Orme is well known for its spectacular scenery and is a popular tourist destination. However, it has been spectacularly ignored by geologists, with only a limited number of academic publications describing its sedimentological and mineralogical history. Over the last 10 years, a team from University of Manchester have been addressing this issue through a series of studies that can provide information not just on the geological evolution of the Great Orme itself, but also on a sedimentological and diagenetic processes that occur on other carbonate platforms across the globe.
In this talk, the composition of the Great Orme Limestone and its bounding successions will be described and used to show how we can start to unravel the importance of tectonic subsidence and changes in relative sea level on carbonate sediments in the Lower Carboniferous. The origin of the spectacular Pier Dolomite succession will be discussed and the timing of the historically and economically important lead and copper mineralization, hosted by the Pier Dolomite, will be considered. Finally, the importance of the Great Orme to the global understanding carbonate depositional and diagenetic processes will be presented.

Cathy is a Reader in Petrophysics & Production Geology, University of Manchester (since 2007), where she co-ordinates Carbonate Research within the Basin Studies Group. She is a carbonate sedimentologist, specialising in diagenesis and pore system characterisation, with over 15 years postdoctoral experience, primarily within the oil industry.

February 20th 2019
A Bronze Age copper bonanza? The Great Orme mine in North Wales.
Speaker: Dr Alan Williams, University of Liverpool
Meeting Room, Pensychnant, Conwy.
Location details and map: Contact/Find

Meeting to commence at 19:30h

Great Orme Mines The Great Orme Bronze Age copper mine in North Wales is one of the largest in Europe but its size was attributed to small-scale part-time working over nearly a millennium based on claims that it only produced an unimportant low impurity type of copper. However, new interdisciplinary geological/archaeological research that used evidence from analyses of minor/trace elements and lead isotopes on the copper ores and metals suggests that Great Orme produced Britain’s first mining boom c.1600 to 1400 BC probably involving a full-time mining community with metal reaching from Brittany to Sweden.

Alan Williams has longstanding research interests in prehistoric and historic metal mining, ores and smelting. Previously chief geologist and head of the R&D raw materials and glass compositions department at Pilkington NSG, he completed his PhD research at the University of Liverpool in 2018.

March 20th 2019
Speaker: Steve Coleman, ex Robertson Research
Meeting Room, Pensychnant, Conwy.
Location details and map: Contact/Find

Meeting to commence at 19:30h

Scoresby Sound In 1969, four geologists from the University of Exeter joined an expedition to East Greenland organised by the Gronlande Geologiske Undersogelse (GGU or the Greenland Geological Survey). The intent of the GGU was to carry out detailed geological mapping of the East coast of Greenland over a 5 year period; 1969 was the second year of this exercise. The four Exeter participants included two senior staff from the University and two undergraduates; the latter were essentially field assistants but combined the trip with their summer undergraduate mapping projects. I was one of those undergraduates.

For the pure geologist the mapping area consisted of migmatised paragneisses derived from sediments of late Precambrian age. The migmatites are interleaved with thick concordant sheets of garnetiferous augen granite/gneiss. The mapping area as a whole is part of the Caledonian mobile belt of East Greenland. Our area of mapping was S.E. Renland, part of the interior section of the Scoresby Sund Fjord, inside the Arctic Circle.

This presentation will enable you to reminisce with me through that time of mapping, entering a landscape almost untarnished by human activity. We will view some classic glaciological features and some rather stimulating geological structures and rock types. We will also come to an appreciation of the logistics of such an expedition. In view of the antiquity of this event (50 years ago!) I have only photographic slides (now digitised) - there was no digital video in those days! I hope you enjoy the evening.

October 9th 2019
Tides and sea levels - through time and space.
Speaker: Sophie Ward, School of Ocean Science, Bangor
Meeting Room, Pensychnant, Conwy.
Location details and map: Contact/Find

Meeting to commence at 19:30h

Tidal Energy One determining factor in the habitability of a planet is its orbit, and fundamental to orbital evolution are the tides. The tides on Earth are dominated by the Earth-Moon system; however, variations in the tides can induce changes to the orbital system itself, since dissipation of tidal energy causes the Moon to recede from the Earth. Ocean models are powerful tools for simulating the evolution of tidal dynamics in response to changes in sea levels and continental configurations. For example, outputs from deep-time tidal simulations shed light on how tidal dynamics have evolved since the Permian-Triassic (252 Mya). As well as helping us to understand the evolution of the Earth-Moon system, the simulation outputs suggest that the Last Glacial Maximum had the largest tides in the last 252 My. Global- and regional tidal simulations of the most recent deglacial period highlight the sensitivity of the tidal models to input parameters, including palaeotopographies, ocean forcing, and parameterisation of ice shelves. Outputs from such tidal models can be used in empirical studies (e.g. understanding the formation of seabed features) as well as for predicting the evolution of the coastline in response to projected future sea-level change. Validation of these ‘palaeo’-tidal models is an ongoing challenge; there remains a need to develop new proxies for past shelf sea hydrodynamic conditions which can be used to constrain numerical model output at regional scales.

Sophie's work on modelling tides has led to collaboration on simulating changes in Northwest European shelf sea tides due to sea-level rise since the Last Glacial Maximum, and exploring the use of seabed sediment grain size as a proxy for past tidal current conditions. Tides and tidal energy are also of interest in the marine renewable energy sector, and in prediction of sea levels.

December 11th 2019
Lyme Regis - "Selling sea shells on the sea shore".
Speaker: Simon Purvis, Robertson CGG Services (UK) Ltd.
Meeting Room, Pensychnant, Conwy.
Location details and map: Contact/Find

Meeting to commence at 19:30h

Tidal Energy Lyme Regis has been recognised as a particularly important geological site for centuries. Considered by many to be the birthplace of palaeontology, and a familiar stomping ground of some of the eminent royalty of the palaeontological community (from Sir Richard Owen to Dave Martil) this small seaside town is home to one of the most fascinating geological records in the world.

Growing up along Dorset's Jurassic Coast World Heritage Site, Simon has spent many years working the various beaches, finding fossils, interpreting the geology and teaching schools and the general public about the fascinating geology of this world-renowned stretch of coastline.

This talk brings some of Simon's experience in the region, giving a broad overview of the depositional environments, stratigraphy and palaeontology of the rock record that can be seen in and around the Dorset town of Lyme Regis.

Tying observations and interpretations to the Jurassic Coast World Heritage Site and wider European stories of the past 190 million years. In doing so, various field techniques will also be explained (with the help of one or two 190 million year old special guests), ultimately allowing any future visitors to the town to have a chance at finding their own fossils and making their own minds up about the fascinating geology of the region.