This 10km (6 mile) walk starts in Austwick village and 2 Robin Proctor’s Scar The Austwick Sandstone blocks were eroded from crags, 7 8 includes the ‘classic’ geological sites of the Norber Erratics The impressive feature of Robin Proctor’s Scar (SD 765696) to the approximately 1km north in Crummack Dale, by a glacier that (a geological Site of Special Scientific Interest) and Nappa west of the path is formed by the reappearance of the limestones diverged from the main Ribblesdale glacier and flowed south- Scar. It provides a walk through over 400 million years of of the Great Scar Limestone Group north of the North Craven westwards into Crummack Dale and uphill to Norber. Recent Earth history reflecting earth movements connected to Fault. The limestone sequence in the area includes the Kilnsey dating of the Norber erratics has indicated that the ice retreated mountain building, deposition in tropical seas, and the Limestone Formation and the Cove and Gordale Limestones of 19,000-18,000 years ago. effects of ice upon the landscape. the Malham Formation. They were formed between 340 and 330 million years ago by deposition in a warm tropical sea, when the area was south of the Equator. The sea was full of life, and as the creatures died the calcium carbonate from their shells and the sea was deposited on the sea-bed to form the horizontal layers of limestone.

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Norber Erratic © BGS/NERC

Follow the path eastwards down the slope towards the stone wall. Nappa Scars is the outcrop to your left immediately after crossing the wall, and continues 3 beneath the path. 2 4 Robin Proctor’s Scar © Philip Barker (cc-by-sa/2.0) 4 Nappa Scars Nappa Scars (SD 768697) is a superb example of an Climb uphill keeping the stone-wall on your right. You will unconformity, a break or time gap in the geological sequence begin to seen numerous erratics to your left.

Liesegang rings in Moughton Whetstone © Adrian Kidd due to erosion or non-deposition. At Nappa Scars the

3 Norber Erratics unconformity is between the Carboniferous Kilnsey Limestone Clapham & Austwick & Clapham Erratics are rocks which have been transported by glaciers from and the slates of the older Ordovician Norber Formation, After parking in Austwick follow the Thwaite road and turn their source region to their new location. The Norber erratics representing a time gap of over 100 million years!

left into Townhead Lane. Follow the lane uphill until you (SD 767700) are a particular type called perched erratics, as the The outcrop exposed on your left is Carboniferous Kilnsey

Ingleborough Stories in Stone Geo Trails Geo Stone in Stories Ingleborough reach the Thwaite Lane crossroads (SD 769692), then turn blocks of Silurian Austwick Sandstone Formation are resting Limestone, with numerous, rounded by weathering, pebbles left and take the footpath towards the Norber Erratics. on pedestals of Carboniferous limestone. The upper surface and boulders of older rocks in its lower beds, forming a The village of Austwick has developed on the glacial till covered of the pedestals was the original rock surface after the ice had conglomerate. The path you are following has been, mistakenly, limestones of the Carboniferous Great Scar Limestone Group retreated, and the pedestals have been formed by the surface taken as marking the position of the unconformity. However, between the North and South Craven Faults. Leaving the village being lowered as a result of the chemical weathering of the the deposits represent the result of the collapse of a pre- at Townend you cross the unexposed North Craven Fault on to limestone (a process called dissolution). To various degrees, Carboniferous sea-cliff, as the Carboniferous sea extended on to 1 older Ordovician rocks. the sandstone blocks have protected the underlying limestone. the ancient ridge. Stories in Stone Geology Trail. Austwick - Crummack Dale section

To see the unconformity involves a scramble down the Cross Austwick Beck and follow the path to Moughton grass covered slope. Great care must be taken as it is steep Whetstone Hole (SD 784719). and very slippery when wet. 7 Moughton Whetstone Hole At the base of the cliff the grey slates of the Ordovician Norber As you walk north-eastwards you cross the west-east trending Formation are exposed. They began life about 445 million Crummack Anticline (a continuation of the Crag Hill Anticline years ago as silty limestones deposited in a shallow sea located in Ribblesdale) where Ordovician rocks are buried beneath the around 30° S. They were then altered, during the Caledonian glacial till cover. At Moughton Whetstone Hole (SD 784719) you mountain building event or orogeny, by folding, uplift and low- will notice, on the ground and in the stream bed, large numbers grade metamorphism into slates. The apparent beds you can of a rock with distinctive red, purple and green bands. This is the Austwick Beck Head Photo © Andy Malcolm see dipping 60-70° to the south-west are the result of cleavage Silurian Austwick Sandstone, which has developed liesegang planes being developed in the slates, on the south-western limb rings due to the weathering of iron oxides in the sandstone. Continue along the path until the junction (SD 778715), of the Austwick Anticline. This process occurred during the drier and warmer conditions turn left and follow the track to another junction (SD Further reading Around 340 million years ago the Carboniferous sea spread of the Devonian when the area was part of a large continental 776704). Turn right, cross Austwick Beck and take the path upslope to Austwick. An excellent overview of the geology of the Yorkshire Dales north and deposited the Kilnsey Limestone on to the eroded landmass. The stone has been quarried as a ‘whet’ or sharpening can be found in: Ordovician slate, forming an unconformity. Initially in some stone, and the derelict remains of some of the Victorian buildings © Tony Waltham - Crummack Dale Geomorphology Map 9 Studrigg Scar places, eroded pebbles and boulders from the eroded used by the quarrymen can still be seen. ‘The Yorkshire Dales – Landscape and Geology’ (2007) by Tony As you walk southwards Studrigg Scar, (SD 781705) to your left ancient rocks were incorporated into the limestone forming Return along the path for about 250 metres until you Waltham and published by The Crowood Press. exposes the unconformity between the Silurian beds and the a conglomerate. At Nappa Scars, a one metre pebbly basal reach a path on your right. almost horizontal overlying Carboniferous limestones. There More detailed information on a wide range of geological conglomerate (a Carboniferous shore-line deposit) can be seen are also extensive scree slopes mainly formed by freeze-thaw topics is available in: resting on the unconformity. Vertical profile of Nappa Scar, adapted from Tony Waltham 8 Austwick Beck Head during periods of periglacial conditions when the climate was ‘Caves and Karst of the Yorkshire Dales’ (2013) edited by Tony Return up the slope to the path, and continue along it colder. A break in the scar is a dry valley formed at the end of the Waltham and David Lowe and published by the British Cave Looking right (to the west) follow the course of Austwick Beck for about 50 metres, until you reach Crummack Lane (SD Devensian glacial period by meltwater. Research Association. upstream and you will see its source, Austwick Beck Head (SD 772696). Turn left and follow the lane northwards to the 776718). This is the spring or resurgence for all the water draining After crossing Austwick Beck you will notice, to your left several The North Yorkshire Geodiversity Partnership thanks Dr Tony junction (SD 772706). from an area of eastern Ingleborough called The Allotment, Waltham for his generous support in allowing the use of outcrops of north dipping Silurian Austwick Sandstone indicating 5 which includes numerous sink-holes including Nick Pot, Juniper illustrations from the two books. Nearing the junction, to the west, crags of Austwick that you are now on the southern limb of the Studrigg-Studfold Sandstone are the source of the erratic blocks at Norber. Ice Gulf and Marble Pot. The basal unconformity between the Syncline Text courtesy of Adrian Kidd Ordovician beds (Sowerthwaite Siltstone Formation) and the moving south through Crummack Dale transported them uphill Cross the track to Sowerthwaite Farm and continue south Geological figures courtesy of Adrian Kidd to Norber. Crummack Dale overlying Cove Limestone of the Great Scar Limestone Group can also be seen. crossing Norber Sike (SD 771694) and Thwaite Lane (SD Geological maps derived from 1:50,000 scale BGS Digital Data Cross the stile and follow the footpath north-eastwards. 770692) back to Austwick. under Licence 2017/096 British Geological Survey, © NERC Crummack Dale Folding 6 Studrigg-Studfold Syncline In the Sowerthwaite Farm area, glacial till obscures the Contains OS data © Crown copyright and database right (2017) Photo © BGS/NERC - Nappa Scar - basal conglomerate After about 250 metres you cross a stream marking the axis of Crummack Dale is one of the Craven Inliers, areas where the younger overlying Carboniferous rocks have been eroded revealing the Ordovician beds of the Austwick Anticline, which were exposed at the Studrigg-Studfold Syncline. The axis runs roughly west-east ancient (Ordovician and Silurian) basement rocks. Nappa Scars, and as you approach Austwick, the North Craven Fault. with rocks dipping to the north on its southern limb and to the The outcrops of rocks reveal a story of extensive folding, during the Caledonian mountain building event or orogeny around 400 This project is part of Stories in Stone, a scheme of conservation south on the northern limb. As you walk along the path, note million years ago, due to crustal plate movements. It was at this time that, geologically, England and Scotland merged. England was and community projects concentrated on the Ingleborough on the western side of Crummack Dale the effect of the pre- located on a southern plate and Scotland area. The scheme was developed by the Ingleborough Dales Carboniferous ridge on the height of the unconformity. It has on one to the north! The effects in this area Landscape Partnership, led by Yorkshire Dales Millennium Trust, risen northwards by 100 metres from Nappa Scars. were to produce a series of major folds as and supported by the Heritage Lottery Fund. Continuing along the path for a further 300 metres you will see compression folded the rocks into a series of anticlines (upfolds) and synclines (downfolds) www.storiesinstone.org.uk the south dipping beds of the Silurian Austwick Sandstone on the northern limb of the Studrigg-Studfold Syncline. These beds trending north-west to south-east. These are a type of sandstone called a greywacke and were formed as include the Austwick and Crummack Anticlines a submarine sediment flow of sand and mud called a turbidity and the Studrigg-Studfold Syncline. Studrigg Scar Photo © Tom Richardson (cc-by-sa/2.0) Photo © Adrian Kidd - Nappa Scar - cliff collapse deposit current. 5 Trow Gill 7 Red lines outline the two walk routes Trow Gill (SD 755717) is a most impressive gorge with 30 metre limestone cliffs, which become even more impressive as the Stories in Stone Trails The map shows the solid gorge narrows westwards from about 40 metres to 3 metres. It The Stories in Stone Trails area has a unique character, but have bedrock geology in the area was originally assumed to be the product of the collapse of a 6 between Clapham and you ever thought why? Much of it results from the rocks beneath cavern roof, but more recent evidence suggests it was formed by Crummack Dale. The cross your feet, the effects of ice and the way human activities have a powerful meltwater flowing from the west into Clapdale. section is a north-south influenced the land since the ice melted. Millions of years of After leaving Trow Gill follow the path for about 500 section through Crummack Earth history have culminated in the landscape, plants, animals, metres. Use the stile to cross the wall on your left. Dale. land use and buildings that make the area so attractive. The area covers the series Ancient roots (over 545 to 417 million years ago) 8 5 of Craven Faults and rock Over 500 million years old, (the oldest rocks in Yorkshire) the formations ranging from 447 ancient roots of the Dales are seen in Chapel le Dale, and the to 316 million years. Ribble valley. Following their deposition they were folded and the 4 mudstones altered to slates. Then a further period of deposition 9 formed the rocks which occur in Crummack Dale. These mudstones and sandstones began life as muddy and sandy submarine flows in a deep ocean basin. 3 Period Group Formation and Member Age Tropical desert (417 to 354 million years ago) Pennine Coal CM 316 MY Measures Group Following the second period of deposition, for almost 80 Trow Gill © Malcom Tebbit (cc-by-sa/2.0) million years, the rocks were uplifted into mountains, folded, Unconformity and under arid conditions, weathering and erosion wore the 6 Bar Pot rocks flat before they were swamped by the tropical seas of the Millstone Grit MG Pendleton Formation 327 MY After leaving Trow Gill, on your left is the head of a dry valley Carboniferous period. Group parallel to Trow Gill, which once carried the meltwaters, which Carboniferous Gaping Gill Main Chamber – Wojciech Rozanski Tropical seas (354 to 330 million years ago) Unconformity formed the waterfall over Foxholes. The path follows the line of a larger dry valley where the darker Hawes Limestone of the The tropical seas deposited horizontal beds of Carboniferous YG Yoredale Group Alston Formation - Hawes Limestone 329 MY Yoredale Group is exposed. To the west of the path, a tributary limestone on the eroded, steeply dipping older rocks producing a valley (following the line of the Hurnel Moss Fault) joins the spectacular unconformity. Shelly limestones packed with fossils GL Malham Formation - Gordale Limestone 331 MY main dry valley. After crossing the stile you will see Bar Pot and limestone reefs prove that around 350 to 330 million years Great Scar CL Malham Formation - Cove Limestone 332 MY (SD 752723) to your left. This is an important entrance, for ago the area was a reef-edged lagoon in a tropical sea. 2 Limestone Group KF Kilnsey Formation 337 MY experienced cavers, to the Gaping Gill system. Tropical swamps and deltas (330 to 290 million years ago) Follow the path for a further 200 metres until it splits, devonian Unconformity The tropical paradise did not last. By 330 million years ago take the path to the right to Gaping Gill (the one to the left mud and sand periodically washed into the tropical sea from silurian SL Brathay, Austwick and Horton Formations 428 MY leads to Ingleborough). river deltas. A cyclic repetition of events formed limestones, Windermere Unconformity mudstones, sandstones and coals. As time progressed, Supergroup the influence of the river deltas became greater and thick ordovician OR Norber and Sowerthwaite Formations 447 MY sandstones and mudstones were laid down. The rocks that Unconformity remain have been faulted, folded and injected with mineral 1 veins. Many deposits have been eroded away, taking with them precambrian IG Ingleton Group 545 MY clues to the events that formed them - nearly 300 million years of rock history are now missing. Stories in Stone Geology Trail. Clapham-Gaping Ghyll section

Buried in ice This 9km (6 mile) walk starts in Clapham and provides an Carboniferous Kilnsey Limestone, forming an unconformity, a introduction to the fascinating geology of the southern break or time gap in the geological sequence caused by erosion © Tony Waltham - A vertical section of Gaping Gill Taking a giant leap forward in time, to between 478,000 and part of Ingleborough. Ingleborough has been designated or non-deposition. Over 100 million years of Earth history is 423,000 years ago, the whole area was buried in ice. Erosion as a geological Site of Special Scientific Interest due to missing! occurred and then much of the landscape was sculpted during Bar Pot © David Brown (cc-by-sa/2.0) 8 Clapham Bottoms its extensive cave systems and other limestone (karst) another, more recent, ice age (30,000 to 18,000 years ago). This Flood water draining through the base of the limestone emerges features. Although limestone is the dominant rock type Clapham Bottoms (SD 758718) is an extensive glacial till covered ice also moulded the gravelly clays of the valley bottoms into from Cat Holes Cave. One hundred and fifty metres further along in the area, other older rocks including sandstones, 7 Gaping Gill dry valley system. Numerous shakeholes (subsidence dolines) rounded hills called drumlins. It transported rocks from far away the path, and 23 metres below, lies Moses Well (SD 751702), mudstones and slates provide evidence of changing are obvious, with three forming a line probably linked to caverns and when it melted left behind rocks called erratics perched on another resurgence also at the base of the limestone. After crossing the glacial till (boulder clay) covered limestone environments and Earth movements. along the Hurnel Moss Fault. At its southern end where it joins different rocks. The unconformity at the base of the limestone varies in height Fell Beck, which drains the southern section of Ingleborough, Trow Gill there is a significant change in height, with a rock From the car park (follow the signs for Ingleborough Cave) can be seen plunging into Gaping Gill (SD 751727), probably the Landslides, waterfalls and gorges due to variations in the ancient eroded surface on to which the step into the lower Trow Gill. Clapham Bottoms is a hanging turn right, and then on reaching the old bridge cross Carboniferous limestone was deposited. Limestone was first Ingleborough Cave © N Chadwick (cc-by-sa/2.0) best known cave system in Britain. Initially, Fell Beck flows over valley indicating that the most recent phase of the incision, by Following the melting of the ice the newly exposed valley sides Clapham Beck. After turning right follow the road until deposited at Moses Well, and later, as the sea became deeper the Hawes Limestone of the Yoredale Group, before entering the meltwater, of Trow Gill occurred after the formation of Clapham were often too steep and unstable leading to large landslides. you reach the entrance to the Ingleborough Estate Nature and spread further it reached Cat Holes at the top of a ridge. As you proceed further north along the Trail, evidence of Main Shaft formed in the Great Scar Limestones and creating Bottoms. Trail. For a small charge you can then follow the route former glacial activity becomes apparent. the longest unbroken waterfall in Britain. The Gaping Gill Cave Where less resistant rocks, such as shale, underlie more resistant towards Ingleborough Cave. Continue along the Nature Trail until you reach System extends for over 17 kilometres, and is 197 metres deep. limestones and sandstones spectacular waterfalls have formed. Ingleborough Cave (SD 754711). 4 Foxholes 2 Cat Hole Sike and Cat Holes Cave The Main Shaft is 98 metres deep and leads into the Main Caves and limestone pavements 3 Ingleborough Cave During the last glaciation, the Devensian, which commenced Chamber, which has been infilled to a depth of 30 metres by As you approach the lake, its dam is believed to be on the line about 27,000 years ago, Clapdale was eroded by south flowing sediment. Three known passages lead from the chamber, In some areas the ice exposed the underlying limestone, Ingleborough Cave is one of three show caves open to the of the South Craven Fault, part of the Craven Fault Complex, glacial ice moving from the main Dales Ice Centre in the Baugh allowing water to flow to the resurgence at Clapham Beck Head. allowing it to be dissolved by slightly acidic rain and soil water. At public in the Yorkshire Dales (the others are White Scar Cave marking the change from the Millstone Grit sandstones and Fell-Wild Boar Fell area (at the head of Wensleydale) through Until the discovery, in 1999, of the Titan Cave in the Peak District, the surface, joints in the rock have been weathered into grikes, (SD 712745) in Chapel le Dale and Stump Cross Caverns (SE mudstones to the south and the limestones of the Great Scar Ribblesdale into Clapdale. Later as the ice melted, many with its 141.5m shaft Gaping Gill held the record for the deepest separating the blocks or clints, producing a unique limestone 089635) east of Grassington). Its entrance is below an impressive Limestone Group to the north. These limestones are well meltwater channels were eroded and extensive glacial deposits shaft in Britain. (For a small fee, on the two summer bank pavement habitat. Enlarged grikes form potholes or sinks where 20 metre cliff, and since the early investigations in 1837, over exposed in the cliff on the east side of the lake, where they dip to were formed. Before you enter Trow Gill you will see, on your left, holiday weekends, local caving clubs provide a winch descent streams flow underground. Frost action has produced extensive 4 kilometres of cave passages have been explored including a the south. Foxholes rock shelter (SD 756715), the overhang having been and return into the Main Chamber.) scree slopes beneath the limestone cliffs or scars. Underground, link to the main Gaping Gill cave system. At one time Clapham The Craven Fault Complex is a series of west-east faults formed by meltwaters flowing along a valley parallel to Trow Gill over thousands of years, caves with stalactites and stalagmites, Beck flowed through the cave but now follows a lower route to From Gaping Gill return along the original route to the wall including the North, Middle and South Craven Faults splitting and forming an impressive waterfall. Ancient human remains have formed. emerge at Clapham Beck Head resurgence (SD 754711) to the have been excavated from the rock shelter together with wolf stile. You can then either return along the Trow Gill route or the area into the Askrigg Block to the north and the Craven north, the main resurgence for the Gaping Gill cave system. take the path to the left into Clapham Bottoms The two trails described in this leaflet provide an opportunity Basin to the south. bones. to explore the classic Ordovician, Silurian and Carboniferous At the head of the lake a rise in the path marks the position of Immediately north of the entrance to Trow Gill, at the geology of the Clapham-Austwick area. Caves - The Carboniferous Great Scar and Yoredale limestones, the North Craven Fault bringing the slates of the Ordovician southern end of Clapham Bottoms, Clapdale is almost have developed their own distinctive karst scenery, the result of Access to a copy of OS Explorer Map OL2 Yorkshire Norber Formation to the surface north of the fault, forming an blocked by a ridge, deposited across the valley by a retreat their calcium carbonate being chemically weathered by slightly Dales: Southern & Western Areas would be helpful when inlier of older rocks surrounded by younger ones. The slates are or recessional moraine (SD 757471). acidic rain and soil water. Where streams flow off the Yoredale following these trails. exposed in the, normally, dry valley bed of Cat Hole Sike. A short and Millstone Grit sandstones into vertical fissures or joints in walk westwards up Cat Hole Sike leads to Cat Holes Cave (SD the rock swallow holes or sinks are formed. As the water moves Moraine – moraine is sediment which has been eroded, 748700) where it is possible to see the unconformity between the underground the joints and bedding planes which it follows transported and then deposited by ice. It consists of clay Carboniferous Great Scar Limestones and the older Ordovician may be enlarged, eventually forming caves. Speleothems, and unsorted angular rocks. Deposited at the base of the © Tony Waltham - Shakehole or subsidence doline Norber Formation. The siltstones of the Ordovician Norber stalactites (hanging from the roof) and stalagmites (on the melting ice, ground moraine (glacial till or boulder clay) Formation were deposited about 445 million years ago, in a Climb the slope to a gate leading onto Long Lane (SD cave floor) frequently form in the caves and sometimes combine is the most extensive, and may be formed into drumlins. shallow sea located around 30° S. They were then altered, during 758716), turn right and follow the lane south until it joins to form limestone columns. Dating of the speleothems in the Terminal moraine occurs at the front or snout of the the Caledonian mountain building event or orogeny, by folding, Thwaite Lane. Turn right and follow the lane back to caves has indicated at least three major phases of formation, ice marking its maximum extent. Retreat or recessional uplift and low-grade metamorphism, into slates. Then, mainly Clapham. at approximately 350,000, 120,000 and during the last 13,000 moraines indicate a temporary pause in the retreat during the Devonian, weathering and erosion, under tropical years. These periods coincide with the major interglacials when process. 9 As it crosses the drift covered Great Scar Limestones, the arid conditions, lowered the surface forming a north west- surface water was able to flow into the cave systems. Upon path offers excellent views of Clapdale and Trow Gill before south east trending ridge of ancient rocks. Around 340 million Gaping Gill © Ian Greig (cc-by-sa/2.0) reaching an impermeable rock layer the underground streams passing over the buried North and South Craven Faults. years ago warm tropical seas spread over them depositing the The path now turns left as you begin to enter Trow Gill. may appear at the surface as a spring or resurgence.