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. 2 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 3 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. 4 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 5 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.