ON THE ROCKS Newsletter of the Yorkshire Branch of the Open University Geological Society December 2017

The view to the east from the summit of Snowdon, with Crib Goch (923m) in the foreground. Crib Goch means red ridge in Welsh, and it is an arête – a knife-edge ridge between two neighbouring glaciated valleys. This ridge is part of the famous Snowdon Horseshoe walking/scrambling route. You can see some close up images here. The ridge is an intrusive rhyolite, and according to BGS, forms one of the most spectacular outcrops in Wales. There is a detailed description of the Snowdonia geology here. (Peter Roberts 11.5.11 Grid Ref: SH 609 543)

Welcome to the last Newsletter of the year Contents 1.Editor’s piece I’ve tried to put together a selection of items which I hope you will 2.Rick’s musings find interesting. If you have any geologically-related items or are 2.YourContents committee happy to share your OU experience with other members, such as 3.Sam’s1. Editor’s journey piece Sam Barratt’s journey to graduation, please send them in as I am 4.2.Human Rick’s- musingsinduced earthquakes always looking for articles and photos. 4.A3.Sam’s useful journey mnemonic 4.Your committee As Rick explains in his piece, the much-anticipated field trip to the 5.Pamela at the Symposium 7.Lincolnshire5.Pamela at the field Symposium-trip fracking site at Kirby Misperton had to be cancelled because of 9.Geologically-themed cakes safety concerns so he was right to do so, although it was a huge 10.Guide to minerals 10. disappointment to those of us who were hoping to attend. 11.Membership matters 11. 12.AGM agenda The agenda for the AGM in Leeds is on page 12, and I look forward 12. 2018 AGM agenda to seeing as many of you as possible on the 27th January. In the meantime, can I be one of the first to wish you a Merry Christmas.

Best Wishes

Peter Ellenger – Newsletter editor

The Yorkshire Branch of the OUGS December 2017

Branch Organiser’s Musings

As I write this I am into preparation mode for our upcoming Blencathra trip. As yet I am not sure if there will be another Blencathra next year, but if so it will be the last one. I am looking at other venues to run a similar type of trip but it will be hard to beat the things I love about Blencathra where everything is there for you, with good food, transport, a bar, and beautiful countryside, but it is difficult trying to keep it fresh by finding new localities each year.

Usually in this edition I would let you know what is coming up in 2018. I can assure you I am busy organising trips and have been in contact with possible leaders, so by the time of the AGM in January I will be able to let you have full details. The AGM in 2018 will be in a new venue in Leeds and we will have a talk afterwards by a good friend of the YOUGS, Paul Hildreth on “Women in Geology”. Anyone interested in being a BO please get in touch!!

You may recall in October I had to cancel a field trip to a fracking site, I wanted to discuss this as many members don’t always get the emails. When organising trips, every now and again I want to organise something slightly different. I thought a trip to a fracking site would be contentious subject but one that members would be interested in. Well I can tell you for sure it was popular; the only issue was that in total I received 312 emails from people wanting to come on this trip. I believe the OUGS is about education so the more the merrier, unfortunately I believe many of the people who expressed an interest in this trip were anti-frackers who just wanted to get inside the plant and create trouble. This would have led to a loss of reputation for a Society which I love, secondly it could have caused security problems for the company, and finally posed a health and safety issue for the genuine members of the Society attending as there are up to 250 protestors at the site at times. In short, I apologise for cancelling the trip, but I would like to do something similar at some point in the future, and when I do I will organise it as a private trip.

Finally, in this Newsletter we have the bio for Samantha Barratt and her Dino who have studied long and hard for her degree. Sam, you have done Yorkshire proud, so well done from us all.

Regards

Rick Savage - Branch Organiser - 07715 215748 - [email protected]

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The Yorkshire Branch of the OUGS December 2017

Sam’s journey to her degree

After losing a few friends and finding myself coming home from work and basically going to bed, I was bored, and looking for something else to do. I’ve always had an interest in space, but I couldn’t even tell you what planets or stars I was looking at. So, I started with the OU on the short (10 point) course Introducing Astronomy. It was a fascinating course, and I wanted to learn more, but realised I was never going to another planet, so enrolled for Fossils and the history of life, followed by Volcanoes, earthquakes and tsunamis.

I finally bit the bullet and went to an OU open day in Leeds where I had a very nice chat with a few of the science people that were there, and the next thing I knew I’d signed up for S104 Exploring Science, and a degree. I’d been told at school (many years ago) I’d amount to nothing and was only good for working on a supermarket checkout!

I finished my first year with three more short courses, but found level 2 more challenging. I took one planetary science course, one environmental, and one geological course (I was still living in hope) and I decided environmental was for me – until I got to level 3 where I chose Ecosystems, and got my worst ever result. To say I was pretty down and ready to throw in the towel was an understatement, and to make it worse all the courses I had planned on doing had been cancelled!

I had also attended the Science Revision Weekend and found the OUGS “stall” where a very excitable and knowledgeable chap gave me an application form which I put it in my folder. I went to see a friend of mine in Kent and started to wonder why is it so flat there, and hilly where I live in Halifax among The Pennines where the views, because of the hills, are stunning. As a result, I reluctantly signed up to “Understanding the continents” a very enjoyable course (but I have to admit, I still don’t understand them ☺). I had also, finally, filled out the form for the OUGS, and eventually attended my first field trip which I found to be a bit overwhelming, but an enjoyable experience. It must have been, otherwise I wouldn’t have gone back for more (with my T-Rex), since when we have become quite the fossil hunters. (Sam related her first field trip experience in the previous edition of the newsletter, ed.)

To finish my final 60 points I signed up for the first presentation of S309 which was very hard work, and some bits of which just baffled the socks of me, but it was a very enjoyable course, and I got my highest grade ever on the examinable part.

My courses have taught me a lot. I’ve also met, and am still in touch with, some great friends, and it would be nice to think my degree is going to get me into a far more interesting job. I’m reading books I’d never hear of (or if I had, wouldn’t have thought they were for me), such as “In search of Schrodinger’s Cat” by John Gribbin, and Carl Sagan’s “Pale Blue Dot”, after which I even attended the festival at Jodrell Bank this year! Although the OU has given me a thirst for learning more, I don’t think I will be going on to do my Masters, unlike some of my fellow students

Sam Barratt

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The Yorkshire Branch of the OUGS December 2017

How Humans Are Causing Deadly Earthquakes

While it has long been known that people can influence seismic activity, researchers were surprised to find that human activity has induced earthquakes with magnitudes as high as 7.9, and that the number of earthquakes is clearly rising in some regions of the world. A study recently published in the (subscription- only) journal Seismological Research Letters identified 728 sites where human activity caused earthquakes over the past 150 years, with mining (37%), dam building (23%), and to a much lesser extent fracking (4%), being among the causes. Mining activities account for the majority of human-induced earthquakes. Photo © azomining.com

A summary, with links to the full report and many associated references, was published in National Geographic Magazine and can be accessed by clicking here.

Of particular interest is the human-induced earthquake database http://inducedearthquakes.org/ which shows the location of all 728 reported instances of activity, and colour-codes the cause of each.

Do you have trouble remembering the sequence of geological periods?

Try using the mnemonic: Camels Cambrian Often Ordovician Sit Silurian Down Devonian Carefully Carboniferous Perhaps Permian Their Triassic Joints Jurassic Creak Cretaceous Terribly Tertiary Quietly Quaternary

Photo. Google “free-to-use”

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The Yorkshire Branch of the OUGS December 2017

If you know of any other useful geology-related mnemonics I will be happy to share them with members.

OUGS Symposium 2017 – lecture report

At this year’s symposium at Musselburgh, Yorkshire OUGS members were a bit thin on the ground, but it was a very enjoyable and informative event, with lots of interesting speakers. The first talk of the weekend was given by Dr Simon Cuthbert, who spoke on “Base Metal to Gold: Mineral Deposits and Evolution of the Scottish Southern Uplands”. He looked at why there was so much alluvial gold in the area, where the general rock type is greywackes.

To the south of the Southern Uplands had been a large ocean and the continent of Gondwana. Debris from the subduction trench during the Ordovician had stacked up several kilometres thickness of sandstones as thrust sheets, creating the Ordovician/Silurian accretionary prism. At the Rhins of Galloway there is a 30km section of shales/slates and sandstone units which dip steeply north.

Burial heating (thermal relaxation) and shear strains, along with magmatic heating, led to precious metal deposits along shear zones, and it is also possible that the Skiddaw slate, which was mineral rich, was pushed under the plate. Sources of metals and sulphur such as pyritic Moffat shales and sulphite ore deposits possibly came from the Skiddaw slates.

Thrust faults provided a conduit of fluids from the depths, with other possible reasons for the mineralisation being: diorites with explosion breccia close to the younger granite intrusions; dyke swarms of lamprophyres which were mafic, full of dark mica, and water-rich and volatile, while primary melts (but not basalts), rich in metals and gold could also play a part.

Geochemistry reflects crustal melt sources plus a contribution of mantle melts. However, there are still some questions since some potential sources span the suture so can’t be subduction related, possibly a section of the Iapetus ocean crust became detached and sank down through the lithosphere, allowing hot asthenosphere to fill the gap. Magmatism provided a heat source to generate fluids, which would carry dissolved volatiles.

Mennock Pass

The breaking up of a series of basins in the area, such as the Sanquhar basin, which was a coal basin of the Late Carboniferous, and rift basins such as Thornhill and Moffat, created half-graben structures which filled with sediments. Reactivation caused a pathway for mineralising fluids as oxidised/acidic waters mobilised and precipitated metals.

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The Yorkshire Branch of the OUGS December 2017

Mining using a method called “hushing” involved digging a dam, blowing it up, and the water washing down the hill.

Alluvial gold found in the area has porous margins and is depleted in silver, similar to tropical gold found today, showing a deep weathering profile. Since the Miocene era, approximately 20 metres of tropical soil has weathered down, perhaps due to a soil bacterial process. The chemistry of gold found in the area shows it to be typical of mafic/shear zones and turbidites.

There are two groups of mineral veins. Some are a similar age to the late Caledonian orogeny while Leadhills, which is remote from the Caledonian plutons, has some factors favouring mineralisation in the area including the cross-fault trend.

When looking for deposits, arsenic is used as a pathfinder element. Factors favouring mineralisation are used to create a “fuzzy map” of potential sites. In Ireland, there are “gold only” deposits in the same rock formations.

Panner’s eye view of the stream Me panning on an earlier trip

As a legacy from the mining, nothing grows on the spoil heaps, but the gangue minerals tend to neutralise the pH of the groundwater so the local water is not too harmful to human health.

In the future, the intention is to try and find more UK sources for minerals, but the economics of the operations needs to be factored in, and whether we want to introduce new industrial landscapes into these areas. There is also the potential of recovering heat energy from old mines.

Dr Cuthbert ended by discussing whether it would be possible to find a “motherlode” and to mine it for the gold it contained.

This obviously led to me asking the question – if they find the motherlode and mine it – what will be left for hobby panners (such as me!) to find in the local streams? Dr Cuthbert’s reply was that it would only be a small-scale operation (if they managed to find it) but that it might even release more gold into the local streams.

I will have to watch out for the university prospectors, looking for the motherlode, when I am off panning again shortly – whilst I content myself with finding specks of gold in the stream bed, if I’m lucky.

Pamela Ross

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The Yorkshire Branch of the OUGS December 2017

Field Trip to North Lincolnshire

Date: 10th June 2017, Leader: Paul Hildreth, Location: Epworth, Lincolnshire.

Three YOUGS members and two guests met with Paul Hildreth on a rainy Saturday morning at Epworth car park. Other YOUGS members may have been put off by the torrential rain and the fierce Lincolnshire border guards. Paul is a committee member of the YGS, and a researcher on the chalk in the north of England. He recently led YOUGS on a trip to look at the Frodingham Ironstone.

The objective of the visit was to examine contrasting rocks from three different time periods, the Triassic, the Jurassic and Cretaceous. Permission is needed from the owners to visit Melwood Quarry and Bigby Quarry.

Locality 1. Melwood Quarry

We shook the rain off of our cagoules and drove to the nearby Melwood Quarry (Fig.1). This is an extensive and shallow former brick quarry which may be reopened soon (possibly for aggregates). It exposes the oldest rocks in Lincolnshire: the Mercia Mudstone group (formerly known as the Keuper Marl) which belong to the lower part of the Late Triassic (245-225my).

Fig.1. General view of Melwood Quarry (photo Peter Vallely) Fig.2. Alternating red and green bands of thinly bedded Triassic siltstones at Melwood Quarry (photo Victoria Jeavons)

Paul pointed out good specimens of salt pseudo-morphs, mud cracks, and gypsum which were lying around on the quarry floor. These provided good evidence that the rocks were deposited in very shallow seas in an arid environment. The quarry walls were composed of mudstones and thinly bedded siltstones which were generally red in colour but with some green bands (indicating periods of reducing conditions). (Fig.2). There were also beds of anhydrite (satin spar) in the lower part of the quarry which proved problematic for brick and tile-making.

After about 40 minutes of hunting for specimens we became partially immobilised by the stickiest of clays and hobbled back to the cars for some shelter.

Locality 2. Elsham Quarry

We then drove about 20 miles east to Elsham Quarry – a small quarry in the Kimmeridge Clay formation of the Upper Jurassic. The Kimmeridge Clay is the source rock of the Dorset mini-oilfield, and is well known for being a crumbly clay and shale deposit 7

The Yorkshire Branch of the OUGS December 2017

However, at this particular site, there is a very rare sand body within the Kimmeridge Clay which has been quarried in the past for building stone. The site used to be an SSSI but lost its status in 1977. It is now largely grassed over with a few large sandstone blocks visible.

We examined the boulders carefully and found some vague outlines of bivalves and ammonites. Paul had found a well-preserved ammonite on a previous visit (Fig. 3.) but sadly they were all hiding from the rain today. And then suddenly, the sun came out and it was summer again. We lounged on the wet grass and enjoyed our packed lunches.

Fig.3. An ammonite –possibly Pictonia from Elsham Quarry (photo Paul Hildreth)

Locality 3. Bigby Quarry

After lunch we drove through some pleasant rolling hills to Bigby Quarry (Fig. 4). This is a fairly extensive quarry with several accessible levels in the Ferriby Chalk Formation (Cenomanian stage of the Upper Cretaceous).

Paul ingeniously overcame the quarry’s barbed wire defences by using plastic pipe-lagging. Then he proceeded to descend into the quarry using an old clothes-line as a handrail (Fig. 5). Bigby quarry must surely be underlain by a low gravity anomaly, as this tiny thread held the considerable weight of each of the YOUGS members with only minor ominous creaking.

Fig.4. Bigby Quarry (photo Victoria Jeavons) Fig.5. Paul Hildreth descending into the quarry (photo Victoria Jeavons)

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The Yorkshire Branch of the OUGS December 2017

The lowest level of the quarry shows the base of the Totternhoe Stone (sometimes referred to as the Grey Bed) which is a flintless chalk. At the base of this bed there are many chalk pebbles resting on a heavily burrowed surface which would have been an exposed hardground for a considerable period. We found several good examples of worm burrows filled with glauconite (a pale greenish mineral) (Fig.6). Fossil echinoids (Holaster), bivalves (Pectenids) and large ammonites (Parapuzosia) have also been found at this level.

Fig.6. Worm burrows and organic matter in Totternhoe

Fig.7. Example of Inoceramus (a bivalve) from the base of Stone formation (photo Victoria Jeavons)

the Welton Chalk. (photo Peter Vallely)

The next level up was the Nettleton Oyster Bed. Within this was a sponge bed, from which we found several convincing fragments of sponges.

Towards the top of the quarry, Paul pointed out the junction of the Ferriby Chalk with the overlying Welton Chalk Formation. It is marked by prominent 50cm organic-rich clay band – known as the Black Band. We found several fragments of fish-scales in the Black Band, but unfortunately no really good examples. The black band is thought to represent a widespread minor extinction event known as the OAE2 or Bonelli Event.

The lower part of the overlying Welton Chalk is also flint-free. We found several good examples of Inoceramus (a bivalve) (Fig.7). The Welton chalk is the equivalent of the Melbourne Rock of Cambridgeshire and Bedfordshire, and marks the beginning of the Turonian Stage of the Cretaceous.

We escaped from the quarry without mishap. We warmly thanked Paul for the excellent field trip. We reluctantly agreed with him that Lincolnshire does indeed have some good scenery and some interesting geology.

Peter Vallely

Field Trips & Meetings

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The Yorkshire Branch of the OUGS December 2017

Next year’s programme of field trips and meetings is still being finalised, and full details will be announced at the AGM and published in the next newsletter.

Other excursion and meeting opportunities

There are many geology trips/lectures in Yorkshire, and elsewhere, which could be of interest. Details of these can be found on the various society websites, below: OUGS http//ougs.org LGS www.leeds.org.uk YGS www.yorksgeolsoc.org.uk/ Down to Earth www.geosupplies.co.uk HGS www.hullgeolsoc.org.uk/ Mid-week Geology Group http://mwggyorkshire.org.uk Friends of Settle Carlisle Line www.foscl.org.uk

Field Trip Insurance

Each person attending field meetings does so on the understanding that they attend at their 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 participants. There may be an element of appropriate cover included in Members’ own household or travel insurance. Members should also note that they will be required to take out appropriate travel insurance for any overseas events; annual travel insurance may be the best form of cover for any Member who regularly attends field events.

Simple guide to minerals - Malachite – CU2CO3(OH)2

Identifying some minerals is not easy; even colour can be misleading. That’s why I’ve started with an easy one. All Malachite is green (often a very bright green) and it leaves a green streak on a ceramic streak plate. As with all minerals the more you see them the easier they can be to identify. Malachite is a copper mineral. Well, the purists will not like that sentence so perhaps ‘a secondary ore of copper’ would be more correct. To get a little more technical, it is a hydrous copper carbonate. It is very close to azurite which is

CU3CO3(OH)2. They both generally form when oxygen rich water seeps into the rock (often limestone in Arizona) that contains copper. The oxidation alters the copper to azurite, and as the weathering continues it becomes malachite. Both azurite and malachite are mined for their copper content. Malachite is relatively soft (hardness 3.5 - 4) and usually has a silky or earthy lustre. It is often found as a crust or as a botryoidal mass. Other forms include fibrous masses and a highly prized banded form. Small monoclinic crystals are found but they are quite rare (meaning - I don’t find any!)

Article and photo kindly provided by Colin Morley - Wessex Branch Organiser Membership and subscription matters

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The Yorkshire Branch of the OUGS December 2017

You will have seen in the recent November issue of the National Newsletter that, for 2018 only, we all need to complete the membership renewal form on pages 15 and 16 of that Newsletter, so could you please ensure you do this if you haven’t already sent it off.

I have also been asked to remind members who pay by standing order to check that their bank is holding an order for the correct amount. You will recall the annual subscription was increased to £22 at the beginning of this year, but I understand a few standing orders are still set up for the old amount.

One of the questions on the renewal form asks if you would like to receive Branch Newsletters via email. While the majority of Yorkshire Branch members do, I would ask those of you who don’t, to consider receiving it electronically instead. If you receive it via email a link to a particular web site or email address, mentioned within an article, is simply a click away. Rather than having to type out the address in full all you have to do is click on the highlighted hyperlink. It will also save the Branch money on printing and postage costs. Please let me know if you are happy to switch.

Finally, if you change your postal or email address, or telephone number could you please let me know so I can update my records. Thanks.

Peter Ellenger

A Happy Christmas to all our readers

©Downtrend.com

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The Yorkshire Branch of the OUGS December 2017

Open University Geological Society Yorkshire Branch AGM Saturday 27th January 2018 to be held at 10.30am at Swarthmore Education Centre* 2 – 7 Woodhouse Square Leeds LS3 1AD Agenda

1. Apologies 2. Welcome 3. Minutes of the last meeting held on 28th January 2017. These appeared in the March 2017 Newsletter. This can be seen by logging into the Members section on the YOUGS website here then continuing to the Members Information Pages. 4. Matters arising from those minutes 5. Correspondence 6. Officers’ reports; Branch Organiser, Treasurer, Newsletter Editor 7. Thanks to existing committee 8. Election of Officers; Branch Organiser, Treasurer, Newsletter Editor 9. Alan Stollery update 10. Any Other Business 11. Date, time and venue of next meeting

After the meeting there will be a talk by Paul Hildreth on Women in Geology

There is a free car park nearby at Joseph’s Well (first left after the Swarthmore building) for use by the general public at weekends, but it does get full. However, it should still have spaces at the time of the meeting. The nearest charging car park is on the left just before the zebra crossing as the road veers right, otherwise the multi storey across from the university is only 5 mins walk away as you head for the Leeds General Infirmary (LGI) and walk along in front of the LGI, over the footbridge over the ring road and you’re there. The train station is not far away and there is normally a bus from the station which stops outside, but this has been suspended during some long-drawn-out roadworks, but it may be running again by late January.

*The Centre’s web site can be accessed here.

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