Mercia Rocks
OUGS West Midlands Branch Newsletter
Issue No 3 September 2020
Winnats Pass, Derbyshire. Jun 2015 - Mike Hermolle
Branch Officers Contents Branch Organiser – David Green Branch Treasurer - Susan Jackson Branch Organiser’s report p 2 Newsletter Editor – Mike Hermolle Message on events p 3 AGM 2020 p 4 Branch Committee Rock of the Month p 7 Emma Askew Local Geology p 9 Sandra Morgan Etymology p 18 Alan Richardson Other Societies P 19 Adrian Wyatt
If you would like to join the committee please do get in touch [email protected] [email protected] 1 Branch Organiser’s Report
I hope everyone is well.
As you might guess the past few months have been somewhat very quit as far as any events happening within OUGS. It is still not certain just when we might be able to arrange to start up again with field trips.
I do have some news however Professor Angela Coe has agreed to be the next president of the OUGS. Unfortunately the AGM that was scheduled for this year has now been cancelled but there will be a “Virtual” meeting on 17th October. If you wish to take part you will need to register by 1st October.
I think that we may have to see if the Branch AGM will also be held as a Zoom meeting but if this is the case I will let everybody know just when this will be held.
Dave Green
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 2020 – In abeyance due to COVID19 restrictions Society Events Situation
Dear Member
Here is a note from Executive Committee to allow us to update you on the current pandemic and how it relates to the Society.
We hope you are all keeping well and not getting too frustrated by the lack of outdoor Society activity around the country.
Previously, the committee took the decision to stop all Society activity until 1 September 2020, other than by virtual means, to keep you all safe in this situation. This date was [email protected] 2 due to be reviewed by mid-June and we have now reached the conclusion that we should continue to shut down the Society activities until 1 October 2020 and review the situation again on 1 August. Unfortunately, this will mean that some more events will have to be postponed. We need to ensure that we are following the government guidance when issued and updated and although currently gatherings of 6 in England are permitted, we feel that this is not suitable for outdoor field trips due to the need to communicate with the leader. There is no certainty when the social distancing restrictions will be lifted. Together with the current uncertainty surrounding travel restrictions, we believe that the continued shut down of the Society’s events is part of our responsibility to keep you safe. Travel restrictions vary around the country so we must adhere to the strictest application of the instructions so that no one feels disadvantaged. In addition, there is no certainty about the Society’s Public Liability Insurance
You will have noticed that the postponed AGM was due to take place in Glasgow on 17 October and we are now going to have a virtual business-only meeting, without social events, using one of the conferencing platforms that have become freely available. This is easier than a further postponement until spring 2021 and have it with the AGM for that year. You will have to register for this event to allow you to take part, however, if you have something to bring to the meeting, please do this through your Branch Organiser who will be able to raise points on your behalf. We are having to do this due to the exceptional circumstances of the current pandemic, so this will have to be an extra-Constitutional meeting.
All information on joining the meeting will be posted on ougs.org when this is finalised.
We are sure that a lot of you are able to continue going on socially distanced geological- based walks, so please keep safe and let us all look forward to next year when we should be able to resume fully.
The Executive Committee of OUGS
Attached to Notice of AGM and AGM Agenda which are below:
[email protected] 3 The Open University Geological Society 48th Annual General Meeting on Saturday 17th October 2020 at 2.00 pm By Zoom digital meeting software Members wishing to participate must register here https://ougs.org/members/information/297/ougs-annual-general-meeting-2020 by Thursday 1 October. Agenda 1 To welcome Members and receive apologies for absence. 2 To thank The AGM organising committee. 3 To approve The minutes of the last meeting held on 6th April 2019. (See OUGS Annual Report for 2019 section now in Proceedings of the OUGS) 4 To discuss Any matters arising from the minutes of the last meeting. 5 To receive Officers’ Reports (See Annual Report) from the
5.1 Secretary 5.2 Treasurer 5.3 Membership Secretary 5.4 Newsletter Editor 5.5 Events Team 5.6 Information Officer 5.7 Sales Administrator 5.8 Branch Organisers’ Representative 5.9 Proceedings Editor/Reviews Officer 5.10 Archivist 5.11 Facebook, Flickr and Forums Moderator 5.12 President 5.13 Chairman 6 To discuss and vote on Constitutional Motions (Appendix 1).
6.1 Change of appeals against non-admittance procedure. 6.2 Branch Constitution – change to allow Associate members to be Branch Treasurers. 6.3 Clarification of attendance of Co-opted post-holders at meetings 7 To elect Secretary, Membership Secretary, Information Officer. 8 To hear any questions from members via Branch Organisers 9 To consider Any emergency motions. 10 To receive Notice of the date and venue of the next Annual General Meeting.
[email protected] 4 APPENDIX 1 Constitutional Motions 6.1: Change of appeals against non-admittance procedure. 8.5 Any such person refused membership shall have the right to make representation orally and/or in writing and to be represented by any other person of their choice. Anyone refused membership by the OUGS Committee may appeal against the decision to the President of The Society. To 8.5 Any such person refused membership shall have the right to make representation orally and/or in writing to the OUGS Committee and to be represented by any other person of their choice. Reason: Being in post for only two years, the President may not be fully aware of the circumstances of any decision behind a refusal, especially those decisions made some time ago.
6.2: Branch Constitution – change to allow Associate members to be Branch Treasurers. 5.2 (i) The Branch Organiser and the Branch Treasurer must be Full Members of The Society at the time of their election and for the duration of their term of office To 5.2 (i) The Branch Organiser must be a Full Member of The Society at the time of their election and for the duration of their term of office No good reason why an Associate Member would not be suitable for that role
6.3 Attendance of Co-opted post-holders at meetings 5.4 The OUGS Executive may co-opt the following post-holders: Co-opted post- holders shall be subject to review every two years.
• a Minutes Secretary for each OUGS committee meeting and OUGS General Meeting
• a Proceedings Editor
• an Administrative Assistant
• a Sales Administrator
• a Gift Aid Secretary
• an Events Coordinator
• the Symposium Organiser(s)
• such other assistants as may prove necessary
These post-holders may attend OUGS Executive and OUGS Committee meetings, but shall not have voting rights at such meetings
To 5.4 The OUGS Executive may co-opt assistants to help with the running of the Society. These may include: [email protected] 5 • a Minutes Secretary for each OUGS committee meeting and OUGS General Meeting • a Facebook and Forum Moderator • a Proceedings Editor • an Administrative Assistant • a Sales Administrator • an Events Coordinator • the Symposium Organiser(s) • any such other assistants as may prove necessary Co-opted assistants may be invited to attend OUGS Executive and OUGS Committee meetings, but shall not have voting rights at such meetings. Co-opted assistants shall be subject to review every two years. Reason: to clarify the position
[email protected] 6 Rock of the Month
Skerry By Adrian Wyatt
The rock of interest is commonly known as a 'Skerry' and is usually referenced on geological maps in the plural as 'Skerries'.
The word Skerry is described as 'an isolated rock', 'rocky reef' or 'sea stack' from the Old Norse term 'rock in the sea'.
As far as I can tell, the term skerries, as used in geology, is only used in the Midlands and this appears to specifically apply to separate beds of hard dolomite-rich sandstone and siltstone. These are distinctive features occurring within the Triassic Sidmouth Mudstone Formation (part of the Mercia Mudstone Group); previously known as Keuper Marl.
Due to the soft nature of the mudstone outcrops are rare. The only places likely to reveal skerry bands are cuttings, cliffs and quarries. All of these are difficult or unsafe to access. However, one or two have been found and examination of the material in- situ has revealed some interesting finds.
The samples of skerries are generally pale green/grey in colour and can occur in thicknesses from a few centimetres to half a metre.
They are a sedimentary deposit formed when the generally dry desert-like plains were periodically flooded by water. The influx of water brought in fresh material from outside of the area and deposited it in local depressions in the landscape. The structure is fine- gained and well sorted. Mineral wise, the beds are rich in dolomite with some calcite and ankerite, barite and anhydrite have been reported.
There are some characteristic features to the skerries. The following are of particular interest.
1. Evidence of mud cracks. 2. Preserved ripple marks 3. Rain drop impressions 4. Salt pseudomorphs. These indicate that there was brackish water. [email protected] 8 Local geology – Cleobury Mortimer
By Mike Hermolle
With the restrictions of COVID19 I began taking more walks on local roads and footpaths (which are managed by the Cleobury Mortimer Footpath Association - https://www.cmfa.co.uk/). I started doing the walks partly to raise funds for the RAF Museum but also started to take a long overdue, closer look at my very local geology.
A prominent feature in the NE corner of the Ludlow geological map (Sheet 181) is the elliptical structure that the town of Cleobury Mortimer is built on - the Cleobury Mortimer Basin as shown in Fig 1. Better seen on the BGS website (BGS, n.d.) as the basin is spread over two paper maps.
Fig 1. Geology of the Cleobury Mortimer area. Extracted from BGS online viewer (BGS, n.d.) [email protected] 9 The area around Cleobury Mortimer is covered by vegetation and rock exposures are few and far between, mainly seen in river and stream beds and banks. The area from the west of the basin to the east is drained by Mill Brook at Hopton Wafers and the River Rea which is the major watercourse indicated by the superficial deposit on Fig 1 crossing the eastern end of the basin. Both run N-S and are fed by streams running in mainly from the west plus minor tributaries from the east. The River Rea flows in a reasonably wide, flat valley north and south of the basin but is in a more restricted ravine-like valley across the basin. Access to stream and river beds is restricted at present. The town is low lying and surround by high ground in all directions as shown by Figs 2 and 3. (Yes the spire is twisted!).
Fig 2. Cleobury Mortimer from the northwest
Fig 2. Cleobury Mortimer from the northwest
[email protected] 10 Dineley & Gossage (1959) describes the syncline as plunging to the east at <35° in the west with dips varying from 16° on the northern limb, 43° on the southern and the westerly dip at the eastern end 10° or less.
The cross sections in Figs 4 and 5 illustrate the topography along and across the basin.
Fig 2. Cleobury Mortimer from the northwest
The low point at 4Km on the long axis is the River Rea. The short axis section clearly indicates the roughly NE-SW grain of the folding described by Butler (1990) as being generated in the Caledonian orogeny and modified in the Variscan.
Deposition of this part of the ORS is described in both Allen (1974) and Wilkinson & Wilkinson (2006) as being riverine due to southward drainage of the Devonian continent which was at the time south of the equator. As shown on Fig 1 the basin rocks are interbedded mudstones and sandstones of the Clee Sandstone Formation (previously Clee Formation) of the Lower Devonian Brecon sub-group resting conformably on and surrounded by the slightly older St Maughans Formation of the Dittonian, although the NW boundary is downfaulted near Hopton Wafers. The type section of the Clee Sandstone Fm is a few km to the NW at Clee Liberty (SO 583848 – 587844) (BGS, n.d.). An inlier of Lower/Middle Coal Measures lies unconformably at the centre of the basin, although no coal is found here. Toghill describes the Clee Sandstone Formation as comprising
“…350m of green and brown sandstones, often cyclical and current-bedded, with only a few thin marls and cornstone conglomerates…
…includes cyclothems and north-westward derived sandstones from North wales deposited on a subsiding floodplain.” (2006, p.160-161).
Table 1 below illustrates the stratigraphic relationships in the basin.
Table 1. Stratigraphy of the Cleobury Mortimer Basin
Mudstones,
-
siltstone and sandstone with
seatearths and coal seams Missing at this location
Westphalian
Coal measures Coal measures Coal
Carboniferous Carboniferous
Lower & Middle & Middle Lower 319Ma Millstone Grit
Carboniferous Limestone 393Ma Sandstone, Upper ORS
coarse-grained,
pebbly; intercalated red-brown and
Clee Fm Clee
Breconian grey mudstone 325m
Siltstone, red-
brown, with
Lower Devonian Lower green, pebbly sandstone and
local Red Sandstone Old Lower Dittonian conglomerate 408Ma FmSt Maugans 300m
Although, as mentioned above, rock exposures are few many walls and buildings in the town are built of local red, brown, yellow and grey sandstones (Wilkinson & Wilkinson, 2006). A wall close to the church demonstrates the variety of stone, Fig 5:
Fig 5. Variety of local sandstones
[email protected] 12 Other noticeable points are copper staining in a wall Fig 6:
Fig 6. Copper staining around a wall block and tufa formation suggesting the presence of limestone on some of the rocks Fig 7.
On top of the marlstones occasionally, carbonate-rich concretionary limestones or calcretes developed due to prolonged desiccation and were broken up by fast-flowing water producing cornstone conglomerates. Some of these are included in buildings. An example is shown in Fig 8, which displays the coarser texture in comparison to the sandstones.
Fig 7. Tufa forming on a wall close to the church
Fig 8. Section of wall with a large block of cornstone conglomerate
Although access to the river and stream beds is restricted, bridges and the occasional access to the bank allows some view of the exposures. Figs 9 -16
Fig 9. Thin Sst beds in feeder stream at SO66554 76519 Fig. 10 Massive Sst blocks in dry stream
Fig. 11 Small Sst blocks in river bed - SO 67712176351 Fig. 12 Possible change in lithology in river bed SO 6790776374 [email protected] 15
By far the best exposure is seen at the disused Ron Hill quarry, the face of which runs for about 100m from SO 6742476273 in an easterly direction about 30m above the river. The fabric ranges from massive sandstone to current bedded as seen in Figs 13 – 16.
. Fig 13. Ron Hill Quarry 1 Fig 14. Ron Hill Quarry 2
Fig 15. Ron Hill Quarry 3 Fig 16. Ron Hill Quarry 4 [email protected] 16 Access to the quarry face is currently restricted and only visible through the vegetation along a footpath which runs alongside above the river. The river is not really visible from the path but in places minor weirs can be heard prompting the question as to their origin as suggested in Fig 11. The quarry face is approximately 10m in height and this exposure may be the reason the Rea changes direction by approximately 70° and runs through the narrowest section of its valley.
With limited access, close examination of the Clee Sandstone Fm is currently difficult and requires further study. In particular the relationship between lithology changes between marlstones and sandstones may have led to the formation of small weirs in the river. The River Rea, over an area wider than the Basin, has seen a variety of industrial processes described in Goodman (1978). The active and very productive local History Society (http://cleoburymortimerhistory.co.uk/chronicles.shtml) has a number of publications which will be available in the Cleobury Mortimer library once it reopens and additional work on the Cleobury Mortimer Basin in the form of an unpublished PhD thesis by D Gossage which may be accessible at Birmingham University on reopening.
An additional area of interest is the, now dry, spring close to the church, known as The Wells which provided the town’s water supply until the 1940s when it was realised that the water was possibly being polluted by the burial ground.
Fig 17. The Wells Fig 18. The Wells in history
The spring initially dried up in 2009 and Wilkinson & Wilkinson (2006) suggest the spring formed due to a marl layer below the sandstone as shown in Fig 19. However one of my neighbours told me that at school they had been taught that the source was close to the village of Farlow, about 6km to the northwest
Fig 19. Origin of The Wells – after Wilkinson & Wilkinson (2008)
[email protected] 17 References
Allen, J. R. L. (1974) ‘Sedimentology of the Old Red Sandstone (Siluro-Devonian) in the Clee Hills Area, Shropshire, England’, Sedimentary Geology, vol. 12, pp. 73–167 [Online]. DOI: https://doi.org/10.1016/0037-0738(74)90007-4. BGS (n.d.) ‘BGS Geology of Britain Viewer (Classic)’, [Online]. Available from: http://mapapps.bgs.ac.uk/geologyofbritain/home.html (Accessed 25 May 2020a). BGS (n.d.) ‘Lexicon’, [Online]. Available from: https://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=CFO (Accessed 1 June 2020b). Butler, J. (1990) ‘A review of the tectonic history of the Shropshire area’, vol. 8568, pp. 20–34 [Online]. Available from: http://www.shropshiregeology.org.uk/sgspublications/Proceedings/1990 No_09 020-034 Butler tectonic history.pdf (Accessed 25 May 2020). Dineley, D. L. and Gossage, D. W. (1959) ‘The Old Red Sandstone of the Cleobury Mortimer Area, Shropshire’, Proceedings of the Geologists’ Association, The Geologists’ Association, vol. 70, no. 3, pp. 221–238 [Online]. DOI: 10.1016/S0016- 7878(59)80020-1 (Accessed 25 May 2020). Goodman, W. G. (1978) ‘Title: Hammerman’s Hill : the land, people and industry of the Titterstone Clee Hill area of Shropshire, from the sixteenth to the eighteenth centuries’, Keele [Online]. Available from: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.483251 . Toghill, P. (2006) Geology of Shropshire, 2nd ed. Marlborough, The Crowood Press Ltd. Wilkinson, G. and Wilkinson, B. (2006) ‘Simon Evan’s Way Features of Geological Interest - A 100 Million Year Walk’, Cleobury Mortimer Footpath Association [Online]. Available from: https://9d2b01d9-b999-43fc-af7d- 97ca465df7df.filesusr.com/ugd/cd6c0e_e9cafbea545f4d4ea10eb31cf57fe1bb.pdf (Accessed 25 May 2020).
Etymology
This edition a slight diversion from geology. Prompted by one of the Chasers in the TV programme “The Chase”. As we are missing Symposium this year I thought this was an interesting addition to my knowledge Symposium - Simpson & Weiner, (2009)
A drinking-party; a convivial meeting for drinking, conversation, and intellectual entertainment: properly among the ancient Greeks, hence generally. Derived from the Greek symposium, via Latin. “Sym” meaning together and “potes” - drinker. Well there’s an interesting thing. And let’s not forget those who participate in symposiums – the symposiasts
Reference.
Simpson, J. A. and Weiner, E. c (2009) ‘Oxford English Dictionary’, 3rd ed. Simpson, J. A. and Weiner, E. C. (eds.), Oxford, Clarenion Press [Online]. Available from: https://www.mendeley.com/catalogue/oxford-english-dictionary-vol-vi/ (Accessed 30 November 2019).
[email protected] 18 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 Indoor meetings will be held in the Abbey Room at the Dudley Archives, Tipton Road, Dudley, DY1 4SQ, 7.30 for 8.00 o'clock start unless stated otherwise Visitors are welcome to attend BCGS events but there will be a charge of £1.00. 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 programme 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 available. 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
Stop Press Save the Branch Money
For those of you who have received a black & white printed copy of this newsletter:
You have received this printed copy because you have not explicitly requested electronic delivery. If you wish to receive the Mercia Rocks electronically in full colour, please e-mail the Membership Secretary at [email protected] with subject "OUGS emails: please revert Branch Newsletter to email", giving your surname and OUGS membership number and we will add you to the email delivery list for the Mercia Rocks which will then revert to a colour email copy. This will save the Branch the cost of postage
Contributions to the Newsletter are always welcome. The subject matter can be anything geological that you think other members would like to read. New items this month are Rock of the Month and Local Geology; please let me have your contributions for the next issue
We use photographs at the head of the title page to make Mercia Rocks a little bit more interesting, attract your attention and show some geology. I need more pictures! Email (to [email protected]) your favourite (preferably local) picture and I will include it in a future issue. It can be a distant general view, or a close up.
Mike Hermolle Items for inclusion in the next Newsletter, by email to: [email protected] by 30 November 2020
Photographs on Field Trips
Extract from Field Trip Guidelines:
There is a sentence on the Attendance Form stating that participants give consent for any photographs taken at events to be used in print and/or online OUGS publications. Please ensure that if any participant does not wish their photograph to be include in any such material, they make this known at the start of the event and that they remove themselves from view when photos are being taken. The leader must also be allowed to withdraw from being photographed. Any person documenting the event for OUGS must not take photographs of any under 16s that may be attending.
Please note that the social media sites of Facebook (OU Geological Society) and Twitter ([email protected]) are official OUGS sites. [email protected] 20