Mercia Rocks OUGS West Midlands Branch Newsletter
Issue No 2 (2017) June 2017
Former Bell Pits near Sheldon Derbyshire—Sandra Morgan (Moyra Eldridge Competition—Highly Commended)
Branch Officers Contents
Branch Organiser – Sandra Morgan Branch Organiser’s report p 2 Branch Treasurer - Susan Jackson Field Trip programme p 3 Newsletter Editor – Mike Hermolle Field trip reports P 6 Other Societies p 27 Branch Committee Notices and Information p 28 David Green, Alan Richardson
If you would like to join the committee please do get in touch [email protected] [email protected] 1
BO Report March 2017 Dear all, After our branch AGM in January and two of Alan Richardson's popular workshops, an Igneous Labora- tory in February and a Metamorphic Laboratory in March, our field trip season began with A Transect of Warwickshire Part Two: The Mesozoic on 2 April. Following last year's successful transect through the older, northern rocks of Warwickshire, led by Martyn Bradley, the aim of this year's field trip was to explore the younger, southern rocks of the county as found in several sites of different ages. We missed Martyn, who was unable to be with us for health reasons, but Paul Stevenson stepped into the breach and provided us with an interesting and varied itinerary.
On 22 April we held our first joint field trip with the Black Country Geological Society, to Mortimer For- est, very ably led by Paul Olver. Our branch has found that numbers on field trips can be quite low and BCGS is finding the same, so it makes a lot of sense to pool resources. For our first joint trip we had 19 participants plus the leader, and this helped to create a very positive mood of energy and enthusiasm, helped by sunshine and interesting fossil finds!
On 29 April Alan Richardson led our third field event, a repeat of his excellent field skills day at loca- tions in Shropshire. This event introduced participants to the methodologies of field recording and interpretation. The group visited three locations: Quatford, Upper Ludstone and Bridgnorth, to devel- op their field investigations skills, focusing on the relative dating of sedimentary formations.
Our next trip will be a visit to Lickey Hills, led by Julie Schroder, on Sunday 2 July. Here we will be able to see Ordovician Lickey Quartzite, Permian Clent Breccia and Triassic Kidderminster Formation. See details in this newsletter.
The Society AGM took place in Milton Keynes on 13 May. Three items from the discussion:
Falling membership numbers were discussed – see the Membership Secretary's report on page 10 of the Annual Report (at the back of the Proceedings). A proposal was passed changing the Membership renewal deadline so that the Membership renewal date continues to be 1 January but the deadline for payment will be 31 January. A proposal was passed limiting branch organisers to a maximum of six continuous years in office. This is to bring branch organisers in line with other members of the Executive Com- mittee.
The AGM weekend also included two lectures, a dinner, visits to OU Earth Science laboratories and a field trip to Combs Quarry for those who stayed until Sunday. The results of the Moyra Eldridge photo competition were announced. The entries can be viewed on the OUGS flickr site:https:// www.flickr.com/photos/ougs_photo_competition/albums/with/72157681186585500 . The winning en- try has been placed in the first position in each section, and is followed by the highly commended im- age(s). Next year's AGM will be held at at the Shap Wells hotel in Cumbria on 21 April.
And finally, a reminder about this year's Symposium, to be held in Edinburgh on 18-20 August. This promises to be an excellent event with a variety of interesting speakers and a range of field trips. For further details see http://ougs.org/society_events Best wishes, Sandra
Forthcoming Field Trips and Events
Each person attending a field meeting does so on the understanding that he/she attends at his/her own risk. The OUGS has Public Liability Insurance Cover for field and indoor meetings, but Personal Accident Cover and Personal Liability Cover remain the responsibility and personal choice of the participant.
There may be an element of appropriate cover included in house insurance or in travel insurance: although OUGS activities are not particularly dangerous, members are advised to check whether exclusions apply to activities in which they plan to participate in case they wish to arrange further cover. An annual travel insurance may be the best solution for any member who regularly attends field events: this again is a matter of personal choice.
Programme 2017 Sun 2 July Lickey Hills. Leader Julie Schroder. Contact Sandra Morgan [email protected] 18-20 August Symposium, Edinburgh. See Society newsletter or website. Sun 1 October South Malverns. Leader John Payne. Contact David Green [email protected] Autumn dates tbn Alan Richardson’s Lab Workshops
Contributions to the Newsletter are always welcome. The subject matter can be anything geological that you think other members would like to read. Items for inclusion in the next Newsletter, by email to: [email protected] by 31 August 2017 We particularly need trip reports, photographs for the header on Page 1 and you’ve seen my “Rocks Thru the Windscreen” —why not submit one for a regular journey you do. Mike Hermolle
Open University Geological Society West Midlands Branch
Lickey Hills Geology and Landscape
Sunday 2nd July 2017
Leader Julie Schroder and members of the Lickey Hills Geo-Champions Group
Meet at 10.15 for 10.30 start at the Lickey Hills Visitor Centre, Warren Lane, Rednal, Birmingham B45 8ER. Grid Ref: SO 997753. Approximate finish time 16.00. After a brief introduction, the morning will be spent following the Lickey Hills 'Champions' trail (approx 1½ miles) examining different outcrops of the Ordovician Lickey Quartzite in the context of the wider landscape. We will examine some surprise findings from recent geoconservation work in Warren Lane Quarry and find evidence of turbulent geological events in the Barnt Green Road 'overfold' quarry. Back at the Visitor Centre for lunch (light snacks available or bring a packed lunch), there will be time to examine maps and other documents. After lunch we will explore the younger formations to the west of the Lickey ridge, via Lickey gorge to Beacon Hill (Permian, Clent Breccia) and returning to the Visitor Centre via Lickey Warren (Triassic, Kidderminster Formation). Approx. 2½ miles. Some steep slopes and rough ground. Strong footwear advisable. Hi-viz jackets recommended, and hard hats for close examination of exposures. The trip is open both to OUGS members and to people who are not members of OUGS. Cost: OUGS members free, non-members £2. For further details and to book a place, email Sandra Morgan at :
Sun 1 October South Malverns Leader John Payne. Contact David Green [email protected] A shared trip with the Black Country Geological society Time and Location Start 10.00. Meet Hollybush car park (free) on north side of the Tewkesbury to Ledbury road at the crest of the Hollybush Pass over the Malvern Hills. Grid Reference SO 759 369. Overview and Geological Interest On this walk we will see the rocks of the south Malvern Hills and their immediate surroundings and discuss the geological aspects of the view from the hill top. The walk starts with a steep 100 metre climb but this is taken slowly and in stages. We visit first the site of a recently constructed earth house to see a thrust fault (an element of the East Malvern fault system). At the top of Raggedstone Hill the scenery, structure and geology of the hill and its surroundings will be described, followed by an early lunch. The first of several volcanic dykes which we shall see on the walk outcrops here. On the south ridge of the hill is an exposure of the Cambrian/Precambrian unconformity which here forms the western boundary of the igneous and metamorphic rocks of the Malvern ridge. Lower on the hill is a quarry showing some of the variety of Malvern’s metamorphic rocks, particularly a phyllonite. We will visit a small waterfall on a Triassic conglomerate of local rocks. A small quarry at Coal Hill shows interleaved Ordovician lava and Ordovician shales. On Chase End Hill, the most southerly of the Malverns, is an exposure of Malvern gneiss. The return to the cars passes an exposure of baked Cambrian shale and a quarry in andesitic lava with a nearby much decorated ancient oak. The final stop will be at the recently cleared roadside exposure at Hollybush, showing two distinct intrusions into the Cambrian Hollybush Sandstone.
Practicalities The tour is scheduled to take 6.5 hours. Estimated finish: 4:30pm
The length of the walk is about 7km and there are some hilly bits. There is one short but steep descent on rather mobile gravel (but on a well-used path) and another on grass.
There are no facilities of any sort on the route of this walk.
Bring a packed lunch.
Wear walking boots and clothing appropriate to the weather.
Field Trip Reports
A Transect of Warwickshire Part Two: The Mesozoic
Sunday 2 April 2017. Leader Paul Stevenson.
Following last year's successful transect through the older, northern rocks of Warwickshire, the aim of this year's field trip was to explore the younger, southern rocks of Warwickshire as found in several sites of different ages.
We started by examining the youngest part of the Warwickshire succession at Crosshands Quarry, a SSSI and site of dinosaur find Cruxicheiros (a large therapod dinosaur) in the early 1960s. Cross Hands Quarry exposes rocks of Middle Jurassic age (approximately 170myrs old) that were deposited in a warm shallow sea. These rocks belong to the Inferior Oolite and consist of the Clypeus Grit, overlain by the Chipping Norton Limestone,
Fig 1 Cross Hands Quarry
.The quarry is now disused but was formerly used for the extraction of Cotswold Limestone. Both of the above formations are oolitic and rich in fossils. Finds on this trip included brachiopods, trace fossils and plant fragments.
From here we drove to Burton Dassett Country Park, a group of hills which rise to 203m above sea level. From the top of the hills, there are excellent views over the surrounding countryside. Our group began by admiring the view from Beacon Hill and discussing possible evidence of glacial erosion.
Fig 2. Burton Dassett view from Beacon Hill
The geology of the area is summarised in the diagram in Image 3. Most of the rocks exposed at Burton Dassett belong to the Lower Jurassic Marlstone Formation and are roughly 175-195 Ma old. The Marl- stone is a calcite-cemented sandstone which is rich in iron: the formation is also referred to as Ironstone because the iron content was just enough (around 25%) for it to be used as a raw material for the pro- duction of iron and steel. Most unusually for a hilly site, the highest land, including some hill tops have been removed for quarrying the ironstone. The ironstone was mostly sent to South Wales. A short indus- trial railway – the Edge Hill Light Railway – existed to transport this ironstone until the 1920s.
Fig 3. The Geology of Burton Dassett. From: WGCG School Project Teacher's Pack for Burton Dassett
We then inspected the rock from which the beacon is built,
Fig 4. Burton Dassett Beacon
Here iron nodules could be observed
Fig 5. Burton Dassett Beacon Wall ironstone
and various fossils were also found, including bivalves, crinoids and even a large plant fragment. [email protected] 8
Fig 6. Burton Dassett plant fossil in Beacon Wall
From here we walked up a neighbouring hill to search for an exposure of Upper Lias. As the diagram shows (Image 3), very little Upper Lias remains at Burton Dassett, but we were eventually successful in finding a small exposure.
Our next stop was a brief visit to Lighthorne Heath Triassic site to view an exposure of Contorta Shale of the Westbury formation. This was a very small grey mudstone exposure with no visible evidence of fos- sils, but Paul had brought along examples of trace fossils from the Westbury formation at Aust and West- bury for us to examine
Fig 7. Lighthorne Heath [email protected] 9
After this we drove on to Lighthorne village. Many of the buildings in the village are constructed from the Langport Member (formerly White Lias) of the Triassic Lilstock Formation. The “White Lias” consists mainly of pale-coloured fine-grained micritic limestone of shallow water origin. We began by examining the “White Lias” wall surrounding the churchyard,
Fig 8. Lighthorne Churchyard
and then went on to examine the “White Lias” walls of the church itself
Fig 9. Lighthorne Church
Our final stop was at Chesterton Windmill. The windmill has a unique design and is a White Lias monument erected in 1632 from a design attributed to Inigo Jones.
Fig 10. Chesterton Windmill
Saturday 22nd April 2017: Field Visit to the Mortimer Forest, Ludlow, Shropshire, Led by Paul Olver (Woolhope Naturalist’s Field Club). INTRODUCTION: The day was very clear and sunny with a chorus of birdsong and colourful flower display for our field visit to Mortimer Forest, Ludlow. The visit was a joint venture between members of BCGS, the Wool- hope Naturalist’s Field Club and the West Midlands branch of the Open University Geological Society (OUGS). We met for 09:30 in the Forestry Commission’s, High Vinnels Car Park, situated off Wigmore Road, west of Ludlow. With Paul Olver (Woolhope Naturalist’s Field Club) acting as our guide the aim of the day was to explore the exposed Middle and Upper Silurian strata of the Mortimer Forest Trail. The Forestry Commission produced a Mortimer Forest trail guide in 1991, which was edited by Andrew Jenkinson of the Shropshire Geological Society. The trail generally follows a route from the High Vinnals car park back along Wigmore Road towards Ludlow. Our day focussed on visiting trail guide Localities 2 to 5 with lunch at the Castle Inn pub, in Wigmore village and a regional view of the local geology from Wigmore Castle Mound. THE GEOLOGY OF THE AREA STRATIGRAPHY The Middle and Upper Silurian strata that we saw on the day belong to the Wenlock and Ludlow Series and are similar to those seen at the Wren’s Nest. Paul mentioned how the British Geological Survey have caused some confusion with changing the names of each individual stratum within these Series and then changing them back again. The older Wenlock Series includes the Coalbrookdale Formation (previously the Wenlock Shale) and the overlying Much Wenlock Limestone Formation (previously the Wenlock Limestone). The overlying and younger Ludlow Series includes the Elton Group (previously the Lower Ludlow Shale), the Bringewood Group / Leintwardine Group and Whitcliffe Group (Previously the Aymestry Limestone and Upper Ludlow Shale). The Elton Group is split into a Lower, Middle and Upper sequence. During our visit we focussed on the Coalbrookdale Formation, Much Wenlock Limestone For- mation and the Elton Group. ENVIRONMENTS AND PALAEOGEOGRAPHY The presence of patch reefs and corals within the Much Wenlock Limestone strata hints at similar ma- rine conditions to those under which Wren’s Nest formed. However, with fewer patch reefs. This com- bined with fossil evidence and turbidite deposits within the Coalbrookdale Formation and Elton Group indicate relatively deeper marine conditions than those found at Wren’s Nest. Looking at the Mortimer Forest geographically, it is situated closer to Wales and further west than Wren’s Nest or the Wenlock Edge in Shropshire. Therefore, it is believed that the rocks of the Mortimer Forest were deposited on the edge of a continental shelf, beyond the reef system that bordered the Welsh Basin. During the Silurian Period the West Midlands was located on the northwest shore of the Avalonian land- mass. Land would have stretch towards the southwest and northeast covering areas such as the Mendip Hills. Further south, Southern England was covered with a shallow marine basin, leading to the Rheic Ocean. To the northwest were shallow marine seas with coral reefs and patch reefs leading to the deep- er waters of the Welsh Basin and out to the closing Iapetus Ocean. The current political border of Eng- land and Scotland also marks the geological boundary of the Iapetus Suture, which formed after the [email protected] 12
ocean finally closed at the end of the Silurian. Like Wren’s Nest layers of volcanic ash, weathered to greenish bentonite, hint at the presence of active volcanoes on the Avalonian landmass. Close examination of the local strata shows them dipping gently, roughly towards the northwest and southeast to form an anticlinal structure referred to as the Ludlow Anticline. The Mortimer Forest Trail Locations are situated on the northern limb of this anticline, the axis of which dips towards the northeast and Ludlow. The same tectonic forces that shaped Wren’s Nest and Castle Hill were at work here. Uplifting the land during the Caledonian Orogeny at the end of the Silurian and finally deforming it during the Variscan Orogeny at the end of the Carboniferous. THE TRAIL Location 1– Gorsty (Locality 5 on the Mortimer Forest Trail): During the day we very loosely followed the Mortimer Forest Trail. From the High Vinnalls car park we walked up the Wigmore Road, back towards Ludlow, to our first stop at Gorsty - a woodland track off the main road with a small quarry approximately 260m along its length. On the north side of the track the beds of the Upper Elton Formation are exposed. Along the length of the track thick bramble covered much of the exposure, which was best seen within the quarry. The exposed Upper Elton Formation comprised weak thinly to medium bedded and fractured purple, weathered to reddish brown and green, flaggy mudstones with occasional calcareous bands. Fossils in- clude free swimming graptolites (Monograptus tumescens) and small brachiopods (Shagamella sp and Lingula lata). The presence of graptolites and lack of bottom living fauna, such as gastropods, supports the idea that these sediments were deposited under relatively deep marine conditions.
Fig 1. Graptolites in the Upper Elton Formation at Location 1 - Gorsty
Location 2 – West of High Vinnals Car Park (Locality 3 on the Mortimer Forest Trail): From Gorsty we walked back along Wigmore Road and past the High Vinnals Car Park, for approximately 270m to our next Location. This location was a small, heavily overgrown, woodland quarry, with an expo- sure of horizontally bedded Lower Elton Formation overlying Much Wenlock Limestone.
Fig 1. Exposure of the Lower Elton Formation overlying the Much Wenlock Limestone, Location 2
The Lower Elton Formation comprised thinly bedded, purple and greenish siltstones, which also con- tained a thin bed of plastic, greenish bentonite clay like those seen at Wren’s Nest. Likewise, such ben- tonite clay beds occur throughout the stratigraphic sequence of the Mortimer Forest and represent ash layers resulting from volcanc eruptions on the Avalonian landmass. According to Paul, chemical analysis of rare earth elements within this layer indicates a source located within the Mendip Hills. At Wren’s Nest chemical analysis of a similarly placed ash layer within the Lower Elton Formation has indicated a volcanic source located somewhere beneath Cheltenham. Paul pointed out that when these layers were deposited there would have been a number of volcanoes erupting in different places. The result was to produce various ash layers at similar positions within the stratigraphic record, but each with its own indi- vidual chemical signature. The underlying Much Wenlock Limestone layer was massive, nodular and equivalent to the Upper Quar- ried Member seen at Wren’s Nest. It is thought that this limestone bed was once worked to produce slaked lime in a limestone kiln across the road at Location 3. Towards the base of this layer a conspicuous thick slot of greenish grey bentonite represents another bed of volcanic ash. This layer has been largely eroded as a result of hammer wielding geology students. Like Wrens Nest the Much Wenlock Limestone layer was rich in fossils, particulary corals (Favosites and Heliolites), and brachiopods (Atrypa, Gypidula, Leptaena, Strophonella and Sphaerirhynchia). Also found within this layer is the coiled gastropod Poleumita, which along with the corals indicates that this limestone was deposited under shallower ma- rine conditions when compared to the overlying Lower Elton Formation. [email protected] 14
Location 3 – Limekiln Quarry (Locality 2 on the Mortimer Forest Trail): On the opposite side of Wigmore Road our next Location was Limekiln Quarry with the limekiln itself situ- ated to the east of the quarry entrance. On the back wall and eastern edge of the quarry are exposures of the Much Wenlock Nodular Limestone, equivalent of the Nodular Member seen at Wren’s Nest. Apart from occasional brachiopod shells (Atrypa and Sphaerirhynchia) and solitary rugose corals on weathered nodule surfaces, fossils were not abundant within this layer. The Nodular Limestone was also quarried for the limekiln. A key feature of this outcrop is a fault plane running along its face, which can also be picked up in the eastern wall of the quarry. Working of the quar- ry has removed much of the fault plane so that only the bottom part remains with horizontal slickensides crossing it. Running a hand along the slickensides reveals that they deepen and form steps of ground up material in the direction of fault movement. The slickensides in the quarry indicate fault movements were generally towards the northeast. From Location 3 we collected cars from the High Vinnalls car park and headed, approximately 7.8km (5 miles) west, to Wigmore Village for lunch at around 13:00. Location 4 – Wigmore Castle Mound After lunch we walked, approximately 600m west, through Wigmore Village and up to Wigmore Castle Mound. The view towards the northeast provided an excellent opportunity to view the structure of the Ludlow Anticline. Directly in front of us the landscape was flat, low-lying and covered with cropped fields. To the left and right the land rose and dipped to form two sets of northeast trending escarpments and dip slopes that met in the far distance. The escarpments represent the dipping strata of the Wenlock and Aymestry Limestone that form the Ludlow Anticline. The lower-lying land between represents the softer mudstone layers of the Coalbrookdale Formation and the Elton Group. From our vantage point at Wig- more Castle Mound we were looking straight up the axis of the Anticline. Noticeably the steep scarp slopes of limestone were covered with woodland, whilst the shallower dip slopes were covered with agri- cultural fields. To the southeast the sequence of limestone escarpments was repeated due to the presence of the north- east-southwest trending Leinthall Earles Fault, which has downthrown the strata to the northwest. Another aspect of the landscape before us were features left behind after the Devensian Ice advance dur- ing the last Ice Age. Today this landscape forms the Vale of Wigmore, through which flows tributaries of the River Teme, which flows from Leintwardine, approximately 4.8km (3 miles) to the northwest of the Castle Mound. From the Vale of Wigmore the River Teme then flows northeast out through the Downton Gorge, approximately 5km (3 miles) northeast of Wigmore Castle Mound and on towards Ludlow, approx- imately 12km (7 miles) northeast. Before the last Ice Age the River Teme flowed southwards, through various gaps in the hills, past the loca- tion of Yatton village, approximately 3km (1.9 miles) southeast to intersect the River Lugg approximately 3km (1.9 miles) to the south. During the Devensian Ice advance, the Wye Valley Glacier crossed this area towards Leominster, blocking the route of the River Teme and stopping its southward flow. However, the river was still being fed from its head waters, which built up to form a vast lake – Wigmore Lake, which covered the low-lying land that we saw before us. As the head waters built up they eventually overflowed through a channel to the north – the Downton Gorge. When Lake Wigmore subsided and the ice retreat- [email protected] 15
ed the River Teme had changed its course towards Ludlow and eventually would meet up with the River Severn. At Yatton village the Wye Valley Glacier also deposited boulders of Welsh conglomerate, rhyolite and ig- nimbrite. Location 5 – Mary Knoll Valley (Locality 4 on the Mortimer Forest Trail): From the Wigmore Castle Mound we walked back to the Castle Inn, picked up the cars and headed back to the High Vinnalls car park. After a short walk, of approximately 900m, along the main woodland road- way and a green waymarked trail we arrived at our final locality for the day - Mary Knoll Valley. Through the wooded valley runs a small stream, the banks of which were heavily overgrown and covered with fallen leaves. Exposures of the underlying bedrock were somewhat limited to a few small eroded patches in the banks of the stream and the stream bed. At this location the bedrock belonged to the Mid- dle Elton Formation, which comprised dark olive green mudstone and siltstone with occasional grey cal- careous bands. Once again fossil graptolites (Monograptus colonus and Neodiversograptus nilssoni) were to be found within these rocks and hint at formation under relatively deep marine conditions. Other fos- sils include brachiopods (Slava sp. and Aegiria sp.), which may have lived attached to seaweed and the trilobite Dalmanites sp. Complete specimens of this arthropod are rare and the avid fossil hunter was only likely to come across a head, thorax or tail. However, the Middle Elton Beds did not give up their prize easily and many members of the party took the opportunity to sit in the sun with a drink and chat.
Fig 3. Looking for trilobites in Mary Knoll Valley, Location 5
I would like to thank Paul for a very interesting field visit and the members of the Woolhope Naturalist’s Field Club and the West Midlands branch of the Open University Geological Society for their attendance. We look forward to seeing Woolhope members in October for the planned visit to the Malverns. For more information regarding the Mortimer Forest trail, reference should be made to the following: Forestry Commission, Mortimer Forest Trail Guide, edited by Andrew Jenkinson, 1991. Andy Harrison [email protected] 16
Field Skills Training Course – 29 April 2017
It was an enormous relief to find the temperature had crept into double figures, and the rain was going to take a day off. Members arrived from all points of the compass having travelled from such diverse loca- tions as Abergavenny, Milton Keynes, Bartley Green, London and Bridlington. As usual, the previous week’s email containing final joining instructions and the course guide had precipi- tated a cancellation from one member. More disappointing was the fact that two members didn’t turn up at all, but didn’t let me know they were no longer coming, and have not contacted me subsequently. Almost everyone was studying on either S209 or S309, and several had no experience of using a compass- clinometer, thereby exactly matching our criteria for the target audience. The morning was spent at Quatford establishing a data-recording protocol on superficially simple outcrops of dune-bedded aeolian sandstones. Participants were guided through drawing field sketches coupled to a sketch plan, measuring strike and dip, plotting readings on a map, lithological description and interpretation as well as hypothesis formulation and testing.
Fig 1. Concave sedimentary layering in the sandstone at Quatford
Fig 2. In a vertical exposure at 900 to the previous one, the bedding has a westerly dip of 20o. If this is dune bedding, the angle of repose of the sand should be around 30o. What has happened to the missing 10o? [email protected] 17
Field Trip Reports Field Skills raining Course 29 April
Fig 3. Strike and dip measurements on another concave structure reveal convergent dips, consistent with the front of a barchan dune. A subsequent measurement of the true dip reveals an easterly dip of 10o, accounting for the apparent anomaly in the angle of dune bedding.
At lunch time, the pub staff were clearly used to dealing with rainy-day pensioners and didn’t realise how anxious we were to get back to the rocks. However, after a little encouragement they were able to deliver our orders, and it was a reassuring to see how comfortable some members were in the non- judgemental company: casting aside any pretence of sophistication one ordered“ Cheesy Chips”, while another favoured the “Fish Finger Sandwich”. Having lost a bit of time, the afternoon was a little more pressured. The upward-fining sequences at Upper Ludstone contain a wealth of data that far exceeds the scope of a single field day, let alone a couple of hours, but offered an ideal opportunity to demonstrate the ad- vantages of graphic logging as a method of data recording.
Fig 4. The cutting at Quatford reveals a series of upward fining sequences of red and green sediments with symmetric ripples, cross-bedding, rip-up clasts, calcretes and conglomerates with contrasting clast lithologies. Aeolian grains in the sediments can be related to the rocks at Quatford, and offer a clue as to the age relationship between the two formations. [email protected] 18
Our data collection had to be focussed on specific targets: sequences and sedimentary structures suffi- cient to provide a basis for a broad palaeoenvironmental interpretation, and evidence for the age of the rocks relative to those at Quatford. Two hypotheses were formulated relating to the latter: only an ex- ploration of the junction between the two formations would allow members to resolve the issue. Thus we set off for the final locality – the Hermitage, sitting on the escarpment of the east side of the Severn Valley overlooking Bridgnorth. A series of exposures provided convincing evidence to confirm the true nature of the age relationship.
Fig 5. Karen Bose puts together the final clues at the Hermitage, and confirms the relative age of the formations based on superposition, included fragments and cross-cutting relationships.
Fig 7. David Caswell makes a final entry in his field notes, while Susan looks in awe at the final exposure.
Fig 6. Alan is assailed by members’ ques- tions at the Hermitage.
Fig 8. Charles Bayne-Jardine, Karen Bose and Carol Williamson wear expressions that reflect the intellectual demands made on them during the day.
Fig 9. Tom Perkins, Charles Bayne-Jardine, Julie Schroder, Kurt Sickelmore, David Caswell and Deborah Browning admire the view over the Severn Valley and Bridgnorth. (Well, they all do, except Tom, who checks his phone!)
During my teaching career I consistently attributed several patterns of behaviour to ‘the teenage condition’. I am now learn- ing, with some wry amusement, that they actually persist into adulthood and must just be another dimension of ‘the human condition’. Apart from people changing their minds about attending and forgetting to mention it, members leave equip- ment behind at the lunch stop (or at home on the breakfast table), take five minutes to take equipment out of the car in which they just deposited it at the last locality, or decide to take a different path to the leader without mentioning it – all just the weft and weave of field courses. It was a great pleasure to spend a day in the field with a group of strongly-motivated and inquisitive students of geology, and share my passion for the puzzles of the rock record.
Alan Richardson
Igneous and Metamorphic Laboratory Workshops 2017
I continue to be humbled by the distances people are prepared to travel to attend these workshops. The latest series has welcomed OUGS members from: East Midlands, West Midlands, Walton Hall, Oxford, London, Wessex, Severnside, North West and East of Scotland branches. Many of those who came this year had attended last year’s session, but wanted to spend more time studying the specimens. As the new teaching collection of specimens has grown, I have been able to change the structure of the workshops. The pdf booklets I send out contain all the background knowledge needed to interpret most of the specimens that will be presented (but I always like to slip in a few that will stretch the more experi- enced members, and stop them from getting bored). Assuming that everyone reads the materials I send out, the introductory lectures have been rendered virtually redundant, allowing me to cut them down to less than fifteen minutes. As much as I enjoy the sound of my own voice, people have come to gain prac- tical experience, not listen to me prattling on. By assembling duplicate specimens into more or less iden- tical sets, I have now been able to produce worksheets that ask specific questions about individual rocks. So, rather than being required to produce comprehensive descriptions of a few specimens, members are directed to the specific distinctive qualities of a rock in order to maximise the range of properties they can interpret in the limited time available.
John Iley drove the 113 miles from the Wirral to attend the workshop; these are his reflections:
Enjoyed the course and the fairly long journey from the Wirral was well worth it. I found the course chal- lenging since I did not have a lot of time to review the reading matter you provided. However, since attending I have had time to review the course content/exercises and this has helped with my understand- ing. I attach my notes about the course which could form the basis of information I would pass on to fu- ture participants to help them understand what the course is about. For me, the driver to do the course was the need to learn more about metamorphic rocks since I am participating in a field study in the NW Highlands of Scotland in May.
This workshop provided the opportunity to look at a wide range of metamorphic rocks from different part of the UK. The rocks had experienced different conditions of metamorphism e.g. regional, contact, dynam- ic and metasomatism. Skills were developed to learn how to recognise the difference between igneous and sedimentary rocks and to learn how to classify metamorphic rocks. Classification was based on tex- ture (grain size, shape and orientation) and mineral composition. Use of a hand lens and grain size chart helped underpin the lithology and minerals present. A series of metamorphic rocks (slate, phyllite, schist and gneiss) helped demonstrate the progression of metamorphic intensity on foliation i.e. slaty cleavage, schistosity and banding. Mineral orientation (foliation and lineation) arising from different strain regimes were related to the rock fabrics. Rocks formed deep in the earth crust under extreme pressure and tem- perature (regional metamorphism) have different index minerals to those formed at lower pressures and possibly higher temperature (contact metamorphism). Index minerals form the basis for Barrovian Zones e.g. chlorite present in low grade metamorphic rocks and sillimanite present in high grade metamorphic rocks.
The afternoon session enabled us to participate in a ‘virtual field study’ in the Glenderaterra valley, Blen- cathra. Here, rocks were seen in context of their position which helped underpin their various lithologies and history. The geological setting, a metamorphic aureole, was not specified but was arrived at be a pro- cess of deduction based on evidence from the field. The provision of specimen rocks and photographs from the various exposures helped underpin the geology. Grid references of the exposures were provided which could be input into a suitable smartphone App (i-geology) and cross-referenced to a geological map. […or could be used to take you to the actual localities in the field. AR] [email protected] 23
Skills in structural geology were developed in terms of orientation and type of folding and cleavage. Structural trends were related to the relevant orogeny. The influence of faulting on the rocks was also examined which produced breccias. Hydrothermal minerals were also evident and attributed to heat from the intrusion producing mineral rich fluids.
Charles Bayne-Jardine was motivated by a need to get more practical experience to help consolidate his understanding of his OU courses:
Thanks for putting on the Metamorphic Petrology Workshop on Sunday. Even though I have completed S209 and am currently struggling through S309 (I never want to see a bulk partition coefficient ever again) I think there is a lot which can be gained from the Workshop. Studying online, without access to practical geology and an informed geologist, means that it is difficult to put the various processes relating to petrology together.
If you are updating your description of the Workshop I think it would be worth mentioning students on S309 as well as S209 as it is now possible to go through OU Level 2 and Level 3 with very little practical geological training (and in my case some misun- derstandings which would not be identified in the assessment process). The same goes for the Igneous Petrology Workshop.
In designing this program of workshops, I had in mind current OU students with little or no practical experience, and previous students who wanted a practical refresher. Recent events have welcomed increasing numbers of S309 students, and this response from current S209 student Adam Wyatt reassures me that I am pitching them at about the right level.
Alan's workshops have provided invaluable ‘hands on’ experience during my study of the OU module S209 and his metamorphic workshop was no exception. The day involved working through wide range of hand specimens and corresponding questions in groups, followed by an outcrop exercise. Alan’s workshop has increased my confidence in interpreting metamorphic rocks and processes, as well as providing a great opportunity to work with other stu- dents and geology enthusiasts. Highly recommended for those studying S209!
Carol Williamson expressed the frustration felt by many over the lack of formal practical training:
Following on from Sunday I can honestly say that I would highly recommend the mineralogy and [petrology] work- shops. In a world of increasingly online delivery of information and virtual specimens I can honestly say there is nothing like a hands on experience. The small groups of mixed knowledge levels make it easy for everyone in- volved to discuss their findings in a relaxed non-threatening atmosphere. Plus, having an expert there to point out what we're missing, explain the different processes involved and clarify some of our misconceptions is invaluable. It is a great learning experience.
The other issue often voiced by current OU students is not only the lack of face-to-face contact with a tutor, but also the lack of opportunities to sit down with a peer group of current students: clearly the digital dimension does not satisfy the social inclinations of many members, and this is implied in Terry Hackwill’s contribution.
Thank you for a very interesting day – I thoroughly enjoyed it. I particularly enjoyed working in a small group. The layout of the tables worked well because all four of us could see and work from the same set of rocks and everyone was involved in the discussion.
I was impressed by the wide selection of metamorphic rocks, particularly because there were several that I have not seen before. I learnt a lot.
Iain Macmillan made a couple of particularly significant points: Thanks for the attached sheets and thanks for the course. It was really useful. What would I say to future students on the course? Make sure you do the reading beforehand as that really helped me. We just worked at our own speed and this worked well - we did not finish but we learnt an awful lot. It is really good actually thinking it all out for yourself. If you are stuck ask Alan. It could have been two days for our group actually as we did not finish either the morning or afternoon. The pdf booklet for each course forms the basis of the understanding that must be applied to the comple- tion of the worksheets, so it is important that members have done the background reading beforehand. With reference to the metamorphic workshop, the intention was to provide more material than the aver- age student could complete in the time available. The morning’s activity is a series of stand-alone ques- tions, each of which provides a small package of understanding. The afternoon exercise is designed in such a way that it can be completed using specimen photographs in lieu of hand specimens; after the workshop members are sent additional materials to allow them to complete the assignment in their own time and check their answers.
In different vein, Bob Nunn may be angling for a job as my tour manager:
Thanks for the answers & a really interesting day on Sunday. I'm a Wessex OUGS member & although we all love to be beside the seaside, Sunday was a timely reminder to me that there's more to geology than sediments. It was great to have the opportunity to handle some 'hard rocks' & my initial struggles identify- ing them showed how much I needed a refresher.
You asked for some feedback. In my view it is quite likely that other Members (in soft rock areas in particu- lar) could be off the pace like me. Your Study Day could form an excellent revision module or even a road- show.
The geology network is very good at spreading news of lectures, workshops and field excursions, so it is gratifying to occasionally have the opportunity to open our activities to a wider audience. Alan Hughes and other members of U3A came to the metamorphic workshop. Alan wrote:
Three of us in our group are very amateur from the Malvern U3A geology and despite our best efforts over various talks and courses our knowledge is patchy and this was highlighted by your exercises BUT that was all to the good and I suspect that we actually learnt more on the day than the others and definitely learned what we don’t know. I wouldn’t hesitate to recommend the workshop to my U3A friends and the 180 members of the geology section would benefit from your instruction any time you have time on your hands. Alan Richardson
Other Geological Societies in the West Midlands Please see the individual websites for events Black Country Geological Society For details go to www.bcgs.info Lecture meetings are held at Dudley Museum & Art Gallery, St James’s Road, Dudley, DY1 1HU, 7.30 for 8 o’clock start unless stated otherwise. Those wishing to attend field meetings please contact the Field Secretary, Andy Harrison email: [email protected] Shropshire Geological Society For details go to:- www.shropshiregeology.org.uk/SGS/SGSintro.html Lectures are held at Shire Hall, Shrewsbury, commencing at 7.15pm for 7.30pm A nominal charge is levied for attendance by non-Members. Warwickshire Geological Conservation Group For details go to www.wgcg.co.uk/ Lectures are held monthly from September to April, Starting at 7.00pm free to WGCG members with non- members £2.00 per lecture. North Staffordshire Group of the Geologists’ Association For details go to www.esci.keele.ac.uk/nsgga NSGGA is the regional group of the Geologist Association North Staffordshire. The winter lecture pro- gramme takes place on the second Thursday of the month from October to March at 7.30pm. All talks are held in the William Smith Building, Keele University. Woolhope Naturalists Field Club For details go to www.woolhopeclub.org.uk The geology section of the club is an affiliated member of the Geologist Association. Lectures are held in the Woolhope room, Hereford Library Broad Street. Field trip programme also availa- ble. For further information on all events email Sue Hay [email protected] Teme Valley Geological Society For details go to www.geo-village.eu
Meetings generally held at Martley Memorial Hall Martley Worcestershire
Full details on the OUGS website http://ougs.org/society_events/details.php?id=17&branchcode=ouc The venue: Queen Margaret University Campus University in Musselburgh, all facilities on site Good public transport links to Edinburgh city centre 2 minutes from Musselburgh train station Accommodation Modern, en- suite single bedrooms, communal kitchen Double rooms / accessible rooms available on request The Edinburgh Festival and Fringe Why not combine a weekend at the Festival of Geodiversity with a trip to the Edinburgh Internation- al Festival and Fringe? QMU offers a perfect base for delegates who decide to stay on.
Notices and Information
BGS Open Day The British Geological Survey is holding an Open Day at its Environmental Science Centre in Keyworth on Saturday 1st July 2017. For more details and a booking form see http://www.bgs.ac.uk/news/events/openday/
New book: Herefordshire’s Rocks and Scenery: A Geology of the County,edited by John Payne, Publisher Logaston Press.
The publisher's website has the following information. Paperback, 256 pages, over 200 colour illustrations ISBN 978-1-910839-16-4 Price £15 The aim of this book is to explain how, where and when the various rocks that underlie Herefordshire were formed and the forces which subsequently worked upon them to result in the scenery we now enjoy. Why is the landscape, the layout of the hills, valleys and rivers, as we see it today? Why, for example, does the Old Red Sandstone, the main rock of the county, have different qualities in different places? How have the various rocks been brought into juxtaposition through plate tec- tonics and fault lines? How, in more recent times, did Ice Age glaciers scour and shape the landscape, forcing rivers to change course and creating hummocky scenery through moraines deposited by ice moving from Wales and the north? Why it is that the Malverns are so prominent and different in outline to anywhere else around? How have the different rocks affected building practices?
With 200 colour photographs, drawings and tables, the book explores the various geological periods and the processes at [email protected] 28