ON THE ROCKS Newsletter of the Yorkshire Branch of the Open University Geological Society June 2019
The cliff at Fleswick, St Bees Head, Cumbria, looking southeast. The cliffs are St Bees Sandstone, which are Early Triassic (approx. 250Ma). BGS describe the cliff composition as sheetflood sandstone (60%), playa mudflat (30%) and minor channel sandstones (10%). There are many examples of the interesting erosional patterns on the beach and under the cliff. More information can be found on the West Cumberland Mining Factsheet here. (Peter Roberts 19.3.18 Grid Ref: NX945133)
Editor’s piece
Welcome to the latest newsletter. I’m afraid that for personal reasons there is no CONTENTS Branch Organiser’s Musings this time, but Rick is hoping to let us have members’ thoughts on the future of the Branch and possible amalgamation with North East 1. Editor’s piece Branch shortly. If you have not let him have yours yet, there is still time to email him. 2. Blencathra Day 2 5. Day out at Royston We have a report on Day 2 of last year’s Blencathra trip by Helen Cuffe and Day 4 by 8. Blencathra Day 4 Earl Howarth, while Tony Felski offers the New Monckton Collieries spoil heap at 11. Branch field trips Royston near Barnsley as a suitable day out for anyone with children or grandchildren. 12. Your committee Thank you to them and to Peter Roberts for the stunning photo above.
On page 11 is a list of this year’s Branch field trips which will include some from Alan Stollery’s Ramblings which were mentioned in the March newsletter. I hope you will be able to attend at least one trip and I look forward to seeing you there.
Peter Ellenger ([email protected])
The Yorkshire Branch of the OUGS June 2019
Blencathra Fieldtrip 2018 – Day Two
CROSS FELL INLIER near DUFTON - Date: 31st October 2018
Fortified with a hearty Blencathra breakfast, we boarded our mini bus, bound for Dufton (Fig. 1) in the Eden Valley. The scenery soon changed as we left the volcanics, lakes and mountains behind and headed into the Vale of Eden Basin with its younger rocks, red sandstone and much gentler topography.
Imagine the surprise of those who hadn’t been before when on reaching Dufton, we saw Dufton Pike and various other Lake District like summits rising ahead. We had crossed the Pennine fault and were looking at the Cross Fell Inlier which is a slice of older Lake District rocks thrust up through and surrounded by the younger rocks of the Eden Basin.
Figure 1 The village green at Dufton sets the scene.
Note:
The water trough built by The London Lead Mining Company, who oversaw lead mining in the area in the 1800s.
Cottages roofed in Skiddaw slate & a barn built of red sandstone, both of which are local building materials.
Dufton Pike in the background.
Our first stop was to view an outcrop of Triassic Age Eden Basin Sandstone (map ref. 685 254) (Fig. 2).
This is the younger rock surrounding our inlier, and applying James and Pippa’s 3xSs + 3xCs formula for investigation rocks (grain size, grain shape, sorting, cementing, colour and composition), we were looking at a fine to medium grain sized; sub angular; well sorted; poorly cemented; red rock, composed of quartz with some muscovite mica
The sub angular shape of the grains combined with some laminations, led us to conclude the sandstone was laid down in water. The red colour indicated iron oxide, which is associated with arid conditions. Furthermore, there is a mine nearby where the evaporite gypsum is extracted. Piecing together these clues we concluded the outcrop was laid down in an ephemeral lake in an arid environment.
Next, we headed along Hurning Lane, which is on Figure 2 Pippa standing in front of an outcrop of Triassic Age the Western flank of Dufton Pike, and things were Eden Basin Sandstone very different.
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The Yorkshire Branch of the OUGS June 2019
James extracted some bedrock (map ref. 691 266), helpfully prized from its setting by an obliging tree root. It was dark grey, fine grained well consolidated Skiddaw slate, just like that surrounding the Blencathra Centre. We had found the edge of our inlier.
The adjoining wall (map ref. 691 268) contained stones which had tumbled down from Dufton Pike itself (Fig. 3). These were a crystalline felsic microgranite of Devonian age, composed of large quartz crystals and small muscovite plates, surrounded by a pink feldspar groundmass.
We paused by a clapper bridge over Rundale Beck (map ref. 691 273) to examine a large rounded boulder of Shap granite with its unmistakable megachrists of pink and white feldspar, quartz and mica (Fig. 4). It’s rounded shape and the fact that there is nothing like it nearby indicates it is an erratic, deposited by a glacier.
Figure 3 Crystalline felsic microgranite Figure 4 Shap granite erratic surrounded by pink felspar groundmass
We stopped for lunch on the north flank of Dufton Pike, nestled below a scree of Borrowdale volcanic ignimbrites which contained clearly visible lines of squashed pumice (map ref. 699 269).
Figure 5. James explaining the limestone valley at Melmerby Scar
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The Yorkshire Branch of the OUGS June 2019
After lunch we headed north east to explore a limestone valley, studded by small mines at Melmerby Scar (Fig. 5) where galena was worked up until 1883 (map ref. 710 270), and where soft, cream coloured barites was extracted from the spoil tips in the 1970s & beyond.
Just before reaching a sizable lime kiln, we examined a limestone scree composed of packstones with abundant crinoid, brachiopod, rugose coral and soft bodied coral fossils which had once lived in a shallow carbonate sea in the Carboniferous.
The death assemblage had not been transported far as the fossils were still fairly intact. All around we found traces of weathered barytes and small traces of galena.
Figure 6 shows a coral in the scree and figure 7 shows a packstone with a lump of barites on top. Carl even thought he found a piece of the nearby Whin Sill in the scree.
Figure 6 A coral in the scree Figure 7 A packstone with a lump of barites on top
A pleasant saunter back to Dufton via the South Eastern flank of Dufton Pike ended a top day with a huge amount of geological variety. We had examined Triassic sandstones, slates, Devonian microgranite, ignimbrite with pumice clasts, an erratic boulder and a limestone valley with its associated fossils and mineralogy- all in the one trip. A fantastic opportunity to get up close and personal with all the above and to piece together the story of their deposition/formation and juxtaposition. A huge thank you to Rick, James and Pippa for putting together such a varied and informative day.
Report and all photos by Heather Cuffe
Are you still receiving this newsletter by post?
There are some members who are receiving a black and white postal copy of the Branch newsletter but no emails which Rick and I send out from time to time during the year. If you would like to receive these emails please write to me at [email protected]. If you would also like to receive the Branch and Society newsletters by email and enjoy them in full colour, and also save the Branch money, please let me know.
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The Yorkshire Branch of the OUGS June 2019
Reclaimed Colliery Spoil Heaps – Mini Geoparks? Until the demise of the UK coal industry in the 1980’s and 90’s the skylines of the coal mining communities of Yorkshire were dominated by winding head gear and spoil heaps, known locally as “muck stacks”. All the spoil heaps have now been lowered, landscaped and planted with vegetation making them look to be a part of the natural topography. Some have been developed into country parks open to the public with two providing an insight into the local geology. In 2008 Barnsley Council decided to landscape the former New Monckton Collieries, Royston spoil heap to create a country park called Rabbit Ings (Fig. 1) (SE37539 11758).
In August of that year the council along with the contractor, the now defunct Carillion and the environmental contractor, Groundwork, invited the public to spend a Sunday afternoon walking over the lowered and landscaped spoil heap to look for fossils.
Figure 1 Fossil-containing shale at Rabbit Ings Country Park
A palaeontologist from Leeds City Museum was on hand to identify any finds. More than 60 people consisting of families and individuals took part finding numerous fossils from the Carboniferous Period. Among the flora found were examples of, Stigmaria - the rootlet of a Lepidodendron tree, Strobili - seed cones from Lycopsid trees, fossilised wood and Neuropteris - a seed fern (Fig. 2). Some of the plant fossils were found in hard mudstone or nodules, but some were found in “fired” clay or shale giving them the appearance of them being terracotta. This is caused by coal fines buried in the stack spontaneously combusting over the years and “firing” any clay or shale nearby. Surprisingly fauna fossils were also found including Conodonts - the teeth of fishlike creatures and Palaeoxyris - the fossilised egg case of a shark which is a very rare find for the Yorkshire coalfield (Fig.3)
Figure 2 Neuropteris - a seed fern Figure 3 Palaeoxyris - fossilised egg case of a shark about 50mm long
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The Yorkshire Branch of the OUGS June 2019
The spoil heap has now been fully landscaped, but a small area at SE 37854 11826 has been purposely left exposed and can be searched for fossils. Other exposures by the paths and drainage ditches can also be searched for fossils. As always when looking for fossils care must be taken not to slip or to disturb deposits that can result in instability. From the top of Rabbit Ings a clear day gives fine views of the Carboniferous Pennines to the North West, the Permian ridge and beyond them the Cretaceous Wolds to the East and the Jurassic Howardian Hills to the North East.
At about the same time that Barnsley was developing Rabbit Ings, Wakefield Council were developing the spoil heap of the former South Elmsall/Frickley Colliery spoil heap into Frickley Country Park (SE 47634 10009). Under the guidance of West Yorkshire Geological Trust, the park was laid out to reflect the importance of the underlying geology to local industry and the importance of a nearby SSSI geological site. Within the park is the Timeline, a 652-metre straight line walk between two steel spires (Fig. 4). The distance between the spires is the depth worked at the colliery from the top of the shaft to the deepest workings. Along the Timeline there are sandstone filled baskets laid out to indicate the seams worked along with their depth, thickness and dip. Within the spires are layers of different coloured stones showing the relationships between the coal seams and adjacent rock.
Figure 4 Frickley Country Park. The end of The Timeline with the “Stromatolites” in the distance
Figure 5 The Shale Disc
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The Yorkshire Branch of the OUGS June 2019
For rock and fossil hunters the “Shale Disc” (Fig.5) contains blocks of local sandstones and magnesium limestones and a block of Carboniferous limestone from the Yorkshire Dales. Though now overgrown with grass searching the surface of the shale disc can result in some fossils being found.
Figure 6 South Elmsall magnesium limestone quarry, SSSI
Frickley Country Park rests virtually on top of the Carboniferous/Permian unconformity so the top of the spoil heap has been landscaped into the “Stromatolites”, a group of mounds representing the fossil reef structures to be found in a Permian magnesium limestone quarry (Fig. 6) some 3 kilometres away at SE483116. Whilst neither site warrant a specific field trip, they can provide an interesting few hours for those with an interest in geology especially with any accompanying children or grandchildren.
Article and photos by Tony Felski
My usual plea for material for the newsletter
I am still looking for items to include in future issues, so if you can help me out please let me have any articles, holiday photos, questions or anything you feel might be of interest to other members and I will be pleased to include them.
Peter Ellenger
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The Yorkshire Branch of the OUGS June 2019
Blencathra Fieldtrip 2018 – Day Four
MAPPING THE ARMBOTH DYKE, THIRLMERE/BORROWDALE – Date: 2nd November
Introduction The mapping party consisted of 10 OUGS members (Fig. 1) led by the resident geologist James from the Field Studies Council at Blencathra. The weather was favourable with intermittent sunny intervals, some cloud cover, good visibility, a little of the Lakeland rain but mainly dry and mild. Armboth Fell is notorious for its boggy ground but the weather had been dry over the previous days and we got off lightly! The task was to trace an igneous intrusion, cross cut by a number of faults, in the Borrowdale Volcanic Group (BVG) country rock. The mapping area is shown in Fig. 2. Figure 1 Group photo on High Tove
Route
The group was dropped off at Watendlath at a height of 263m, NY 274 164, and began the climb to the High Tove cairn at 510m, NY 28915 16510.
The Topography Armboth Fell is part of central Lakeland’s extensive upland fells, sitting high between Thirlmere and Borrowdale, centred around High Tove and High Seat. It is rather featureless rolling moorland with rounded hillocks, depressions, steep sided gills, and is wet, wet, wet with the renowned Alfred Wainwright blanket bog! There are numerous rocky outcrops which add interest.
Figure 2 Mapping area, courtesy of Helen Cuffe
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The Yorkshire Branch of the OUGS June 2019
The geology of the area
The superficial geology is the till of the Devensian, with ice cover maximal 18-24 thousand years ago. The bed rock is the Birker Fell Formation of the BVG, mainly andesite and dacite volcanic rocks, formed in the Ordovician, 449-458 million years ago, during island arc activity at the time of the Iapetus closure.
The Armboth Dyke is exposed, amongst other rocky outcrops, in a series of disconnected segments. We were looking to identify the characteristic pinkish-coloured microgranite dyke, with quartz and feldspar crystals weathering out, and distinguish it from the igneous extrusive country rock, the grey- brown coloured andesite/tuffs of the BVG, into which it intruded in the Devonian, 393-419 million years ago.
Figure 3a The country rock Figure 3b The country rock in detail – andesite/tuff
The Mapping Exercise The group was instructed in the basic principles of mapping – including safety in the field, navigation, pacing, transferring bearings to the map, landscape and rock description, accurate and careful recording in the field and interpretation of the geology.
The dyke is exposed in a NW-SE orientation, approximately 5-10 m wide, and it would probably have been possible to identify most if not all of the disconnected intrusion suite segments over a length of 2km, the disrupted pattern of which is thought to be due to strike-slip faults. However, we only had sufficient time to map one segment.
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The Yorkshire Branch of the OUGS June 2019
Figure 4 The pink-coloured microgranite Intrusion Figure 5 Specimen of the weathered microgranite
Conclusion
The OUGS group had an enjoyable day’s introduction to geological mapping at Armboth Fell which is a well-recognised area for teaching the principles of mapping. Some of us had previous experience but certainly not all. Geological mapping is a basic skill that a geologist should acquire early in their career; mapping must be learned in the field and the multi-skills and experience required cannot be achieved in the classroom.
The intrusion is quite extensive and stretches over a distance of 2km, in disconnected segments. We only achieved part of a full mapping task, and mapped only one segment of the intrusion suite, but all agreed it was a valuable exercise and a good introduction to the complex and challenging discipline of geological mapping.
Report and all photos by Earl Haworth With thanks to Heather Cuff for providing the annotated mapping area
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The Yorkshire Branch of the OUGS June 2019
OUGS Yorkshire Branch 2019 field trips June – Saturday 15th at 10.30 Greenhow Geology Trail, Greenhow, Pately Bridge, North Yorkshire – led by Tony Felski
A 6km circular walk to observe the geology and its influence on local industry past and present.
Meet at 10.15 for 10.30 start at the Toft Gate Quarry (free) Car Park (SE12961 64384) on the B6265 between Pately Bridge and Grassington. Full details are on the Branch website here. If you have any queries please contact Tony Felksi on 07836 574688. June – Wednesday 19th – Sunday 23rd Mapping the Lake District
There are still a few places remining on what promises to be an interesting, informative, and fun week. Full details were given in the December 2018 newsletter, which can be accessed here, or by contacting Rick Savage at [email protected] or by telephone on 07761 409807.
July – Saturday 27th at 10.30 Field trip to the Burbage Valley (10 miles SW of Sheffield) – led by Peter Vallely
A10km circular walk on mainly good paths with some optional scrambling, to examine the relationship between geology and scenery in the spectacular Burbage Valley.
Meet at 10.15 for 10.30 start at the Upper Burbage Bridge car park (SK261 830). If this is full there is plenty of roadside parking. Full details are on the Branch website here. If you have any queries please contact Peter Vallely on 01142 363991
September – Saturday 7th at 10.30 Field trip to Monsal Dale (four miles NW of Bakewell, Derbyshire) – led by Peter Vallely
An 8km circular walk with a few steep ascents and descents on good paths, to examine the Carboniferous limestones and their relationship with volcanic lavas.
Meet at 10.15 for 10.30 start outside the Monsal Head Hotel (SK 185 715). There is a large pay and display car park (with toilets) behind the hotel or free roadside parking about 200m away in the direction of Great Longstone. Full details are on the Branch website here. If you have any queries please contact Peter Vallely on 01142 363991
October – Sunday 6th at 10.30 Field trip to Austwick to see the Norber Erratics, Crummackdale, and if time permits Moughton Scar - led by Tony Felksi. This is the walk postponed from last year.
Walking distance 8 to 11 km depending on which options we decide to take on the day. Relatively easy walking to view a number of features including Ordovician and Silurian basement rocks. typical Dales limestone scenery, an unconformity and glacial phenomena.
Meeting point where roads and tracks cross just above Austwick Town Head (SD76950 69200). There is limited road-side parking at this location but there is good road-side parking in Austwick itself at SD76898 68640.
Full details are on the Branch website here. If you have any queries please contact Tony Felksi on 07836 574688.
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The Yorkshire Branch of the OUGS June 2019
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.
Other Branches’ 2019 field trips
Field trips run by other branches can be found in the latest national newsletter by logging on here
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 https://ougs.org/events/ LGA http://www.leedsga.org.uk/ YGS www.yorksgeolsoc.org.uk/ Down to Earth https://www.geosupplies.co.uk/ HGS www.hullgeolsoc.org.uk/ Mid-week Geology Group http://mwggyorkshire.org.uk/ Friends of Settle Carlisle Line https://www.foscl.org.uk/
2019 Committee Members
Branch Organiser Rick Savage 07761 409807 [email protected] Treasurer Jean Sampson 01142 363991 [email protected] Newsletter Editor Peter Ellenger 01759 303095 [email protected] Webmaster Dave Beever 07804 831962 [email protected] Event Officer Peter Vallely 01142 363991 [email protected] Committee Member Jenny Jennings 07868 023734 [email protected] Committee Member Phil Robinson 07867 974893 [email protected] Committee Member Michael Gagan 01142 214630 [email protected]
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