The hillside quarries above Stockdale Farm in Longsleddale expose Late Ordovician fossil-bearing rocks of the Stile End Formation. Their scientific importance includes type material of trilobites, although loose spoil commonly preserves incomplete, weathered moulds. Arrange access and collecting permission with the landowner before visiting these steep, exposed workings.
FIND FREQUENCY: ♦♦♦ – Trilobites and other shells are recorded, often as incomplete or weathered moulds. The historical rating is not a guarantee of present-day finds.
CHILDREN: ♦ – The steep hillside approach, uneven rock and old quarry edges make this unsuitable for children’s collecting.
ACCESS: ♦♦ – An upland walk from the narrow Longsleddale valley road. Confirm the approach, parking and permission before entering quarry or spoil areas.
TYPE: – Two abandoned hillside quarries with cleaved sedimentary rock and loose spoil; distinct from the Silurian beds in Stockdale Beck.
DIRECTIONS
♦ From Kendal, follow the A6 north and turn into Longsleddale, following the single-track valley road towards Sadgill. Use passing places considerately and keep farm access clear.
♦ The original approach turned towards Stockdale and continued past the farm and older buildings towards the hillside quarries. The geological type locality is about 400–450 m north-north-west of Stockdale Farm. Agree the final approach with the landowner rather than assuming that a visible track permits quarry access.
♦ Use an authorised parking place without blocking passing places, gates or entrances. The old guide’s roadside and grass spaces are not confirmed parking arrangements; ask locally before leaving a vehicle.
♦ BGS quarry stratotype: NY 4887 0569. The original UK Fossils marker is 54.44775°N, 2.78658°W; check the mapped quarry and agreed route rather than treating that older marker as a verified entrance.
FOSSIL HUNTING
Stockdale Quarry is particularly important for trilobites from the Stile End Formation. Much of the studied material consists of isolated head or tail parts and moulting remains, rather than complete animals. Decalcification has removed some original shell, leaving external or internal moulds; later deformation may have stretched or distorted them. Examine shape, ornament and the part preserved, rather than identifying a specimen from its outline alone.
Ascetopeltis apoxys was described from quarry material, with its holotype, SM A98177, an internal mould of the central part of the head shield from locality 8b. The study included 47 moulting remains from several quarry collecting points. An articulated paratype came from Kentmere, however, so that specimen cannot be used as evidence that complete examples are common in the Stockdale spoil.
The tail-shield holotype of Erratencrinurus kingi, SM A51706, also came from the Stile End quarries above Stockdale Farm. The species was originally described as Encrinurus kingi and later reassigned after better head material became available. Other documented quarry trilobites include Toxochasmops marri and a specimen of Gravicalymene susi. The type specimens of those last two species came from other localities, so the quarry’s importance should not be overstated.
The original visit also reported brachiopods, gastropods, bivalves, corals and graptolites, but those broad observations do not provide an independently established species list or an exact bed for each find. The strongest documented identifications are the trilobites studied in the systematic literature. Weathered brown or orange surfaces at the edges of slabs may reveal moulds, but colour alone is not evidence of a fossil.
During a permitted visit, first look at surfaces already exposed on securely resting loose material, without moving supporting blocks or disturbing a slope. The old guide found some clearer fossils on less-weathered slabs, but the arrangement of spoil changes and an old stack is not a guaranteed collecting place. There is no reason to attack a quarry face or split rock simply because the locality is fossiliferous.
Record which quarry a specimen came from and whether it was loose. The research locality numbers 7a, 7b and 8a–8c are collecting points, not numbered beds in a vertical succession. Keep a scale in photographs, retain counterpart surfaces where present and avoid trimming potentially useful trilobite material in the field. Any removal must comply with permission from the landowner and relevant conservation conditions.
Significant discoveries, geological research and conservation milestones at Stockdale Quarry.
1963 – A quarry trilobite is described
Dean described Encrinurus kingi from a tail-shield type specimen from the Stile End quarries above Stockdale Farm, associated with W. B. R. King’s collecting.
1979 – Ascetopeltis apoxys is named
McNamara described this trilobite using quarry material, including the cranidial holotype from locality 8b.
1979 – The King trilobite is reassigned
Better head-shield evidence supported the name Erratencrinurus kingi. The author recognised the material as the first British occurrence of that genus.
1979 – The Stile End fauna is placed in the Cautleyan
Palaeontological revision placed the beds in Cautleyan shelly Zone 2, superseding older late-Caradoc or Actonian interpretations.
1986 – A geological survey of the district is published
The Kentmere–Crook survey provided work subsequently cited in the modern Stile End stratotype description.
1994 – The basal conglomerate is incorporated within Stile End
A revised Windermere stratigraphical hierarchy treated Longsleddale as a member of the Stile End Formation, changing the scope of the formation name.
2012 – BGS formalises the quarry stratotype framework
The published framework specified the Stile End stratotype in and north of the disused Stockdale quarries and retained the Longsleddale Conglomerate Member within the formation.
GEOLOGY
The quarry fossil beds belong to the Stile End Formation of the Dent Group, within the Windermere Supergroup. Their shelly fauna places them in the Cautleyan part of the Late Ordovician, traditionally within the Ashgill. This is a different geological setting from the younger Silurian Stockdale Group in Stockdale Beck, despite the similar place names.
The Dent succession developed across an irregular volcanic landscape. At its base, the Longsleddale Conglomerate Member contains locally derived volcanic debris and fines upwards into sandstone, with red or green laminated siltstone in places. Fossiliferous calcareous siltstone, nodular limestone and pebbly sandstone occur higher in the Stile End succession. These rocks record marine sedimentation around the volcanic terrain rather than a single uniform slate bed.
Modern and historical accounts use different boundaries for the Stile End Formation. The older, narrower concept has a maximum thickness of about 50 m, whereas the expanded BGS framework incorporates the basal conglomerates and reaches much greater thicknesses regionally. Neither number is a measurement of the two visitor quarries. Their importance as a stratotype and fossil locality does not mean that a continuous, fully measured sedimentary column is exposed in either face.
Later deformation produced the cleavage that gives many loose pieces their slabby appearance. Weathering and dissolution of shell material explain why fossils can survive as moulds and why incomplete specimens may still carry useful features. Quarrying and movement of spoil have then mixed material from different positions. Nearby Yarlside volcanic rocks and overlying Kirkley Bank limestones belong to the wider succession, but their thicknesses and fossil assemblages should be kept separate from the documented quarry material.
Detailed geology and trilobite type material of the Stockdale hillside quarries
This account concerns the two hillside quarries north-north-west of Stockdale Farm, together with their fossil material and spoil. The BGS Stile End stratotype lies in and north of the disused quarries at NY 4887 0569. McNamara’s collecting points 7a, 7b and 8a–8c belong to these workings, about 450 m north-north-west of the farm; they are not numbered beds.
BORROWDALE VOLCANIC GROUP
Older substrate and the basal unconformity. The Dent sedimentary succession begins on an irregular erosional surface cut into volcanic rocks. This is the geological foundation of the type area, not the fossiliferous sedimentary spoil itself. No thickness for a complete volcanic substrate or an exact measured quarry contact is supplied.
DENT GROUP
Stile End Formation
The fossiliferous rocks are Late Ordovician, within the Cautleyan and shelly Zone 2. This corrects older late-Caradoc or Actonian assignments found in historical catalogues. The modern framework includes the basal conglomeratic member within Stile End. Its maximum thickness of up to 400 m is regional, whereas the older, narrower formation definition has an approximately 50 m maximum. The two figures describe different concepts and neither is an observed quarry-face height.
Longsleddale Conglomerate Member
Basal conglomerate and fining-upward sediment. Locally derived volcanic detritus forms poorly sorted conglomerate in fining-upward cycles, passing into sandstone with laminated red and green siltstone in places. The upper transition into the overlying Stile End beds is abruptly gradational. The member is interpreted as sediment from local alluvial fans advancing into a marine embayment, with wave reworking and offshore transition into calcareous mud. These are formation and member interpretations, rather than a measured sedimentary profile of either quarry face. The regional range is approximately 0–65 m; there is no evidence that either visitor quarry exposes a 65 m member thickness. The type-area exposures extend near and north of the quarries. Sporadic shells in formation-wide descriptions do not establish an exact quarry species list for this member.
Stile End Formation: beds above the basal member
Main fossiliferous Stile End beds. Calcareous siltstone, nodular limestone and pebbly sandstone host the documented quarry fauna. Cleavage and weathering produce slabby material, commonly with decalcified internal or external moulds. No continuous numbered bed series or bed-by-bed measured section for the two workings is established in the recovered accounts. The fossil occurrences below identify collecting sites, rather than a complete vertical sequence.
Ascetopeltis apoxys: quarry type material. Holotype SM A98177 is an internal mould of a cranidium from locality 8b. McNamara studied 47 moulting remains from quarry localities 7a, 7b, 8a and 8b. The articulated paratype HM A15430 comes from Kentmere, a separate locality, so it does not establish complete articulated preservation in the Stockdale spoil.
Erratencrinurus kingi: the type tail and later head evidence. Holotype SM A51706 is a pygidial internal mould from quarry locality 8c above Stockdale Farm, associated with W. B. R. King’s collecting. Supporting cranidium BM It8328 came from Longsleddale locality 11 at the same horizon, a distinct collecting point rather than one of the numbered quarry localities. This additional material supported reassignment from the original name Encrinurus kingi. McNamara regarded this as the first British record of the revised genus. The separately catalogued paratype SM A51705 is a museum record, not a newly collected specimen.
Toxochasmops marri and Gravicalymene susi. The former is recorded from quarry localities 7a, 7b, 8a, 8b and 8c, but its holotype is from Applethwaite Common. The latter includes material from quarry locality 8c; its holotype is from a separate locality downstream in Stockdale Beck, 25 m above the base of the historically named Applethwaite Formation. An abundance percentage for the entire studied Stile End assemblage does not predict the frequency of either species in visitor spoil.
Other shell reports. The original visitor account lists brachiopods, gastropods, bivalves, corals and graptolites. These remain broad historical observations without a verified quarry species list or bed provenance for each group. They are distinct from the tightly documented trilobite records above.
Quarry spoil. Modern piles and scree contain moved cleaved slabs, including weathered mould-bearing pieces. They are not an in-situ stratigraphic horizon and their arrangement cannot reconstruct a bed succession. Collecting-point and loose-spoil labels remain important scientific information even when a precise bed is unknown.
Overlying Yarlside volcanic rocks: neighbouring context. The wider succession includes the Yarlside Volcanic Formation above the sedimentary beds. Its approximately 180 m type section and basal 45 m flow-folded interval belong to the nearby Stockdale Beck volcanic account, not to a measured log of either fossil quarry. Rounded spherulitic structures in felsite are volcanic features and should not automatically be identified as corals.
Kirkley Bank Limestone above the volcanic interval. Carbonate-rich marine beds, including a basal felsite-pebble conglomerate, occur above the Yarlside rocks in the surrounding succession. No measured exposure of these beds in the two fossil quarries was verified. Their shelly fauna and thickness remain separate from the Stile End quarry records.
References.
Millward and Stone (2012), BGS stratigraphical framework, Stile End Formation and Longsleddale Conglomerate Member.
McNamara (1979), Trilobites from the Coniston Limestone Group, pp. 53–92.
BGS Lexicon: older, narrower Stile End Formation definition.
BGS Lexicon: Longsleddale Conglomerate Member.
Millward, Geological Conservation Review: neighbouring Stockdale Beck volcanic section.
BGS type-fossil database: Erratencrinurus kingi paratype SM A51705.
SAFETY
The approach crosses a steep upland hillside, with slippery grass and rocky outcrops. Wear boots with a firm grip, carry waterproof clothing and avoid wet, icy or deteriorating conditions. Longsleddale’s single-track road can also be affected by flooding.
Keep away from old quarry edges, unstable faces and loose scree. Do not stand below a face, climb a spoil heap or pull out a slab that supports other rock. The old guide’s emphasis on loose material does not make every heap safe to approach.
Plan the route and return before setting out, and let someone know your plans. These are exposed hillside workings rather than a family collecting area.
EQUIPMENT
Bring sturdy boots, weatherproof clothing, a map, drinking water, a hand lens, a camera and a photographic scale. A small notebook is useful for keeping the two quarries and any loose-spoil observations distinct.
Where the landowner has agreed to collecting, use soft wrapping and a rigid box for delicate mould-bearing slabs. Avoid unnecessary hammering or field trimming, which can remove useful morphology and destroy counterpart surfaces.
CLEANING AND TREATING
Many of the trilobites are preserved as decalcified moulds in cleaved rock. Begin with a soft dry brush and support the whole slab while handling it. Do not scrub, force the rock apart or wash a friable specimen aggressively.
Avoid acids, bleach and routine varnish. Keep the original label, locality information and counterpart pieces together. A possible type-quality or unusually complete specimen should remain unprepared until it has been examined by an appropriate specialist.
IDENTIFY YOUR FINDS
Need help identifying a fossil? Share clear photos, where you found it and its size with the community.
FURTHER READING
Deposits: the volcanic history of Cumbria, regional background
McNamara (1979): trilobites of the Lake District’s Coniston Limestone Group
BGS (2012): Dent Group and Stile End stratigraphical framework
BGS Lexicon: Longsleddale Conglomerate Member
Natural England: Browgill and Stockdale Becks SSSI
GCR: neighbouring Stockdale Beck volcanic section
ACCESS RIGHTS
Ask the landowner before entering the quarry or spoil areas and before collecting. Public walking access does not grant specimen-removal rights. Leave quarry faces, outcrops and spoil slopes undisturbed, and follow any local conditions.
The wider Browgill and Stockdale Becks SSSI protects important exposures in this area. Check the official boundary and obtain advice before proposed scientific sampling; the designation does not establish unrestricted access or general consent to split spoil. Any required consent should be arranged with the landowner and Natural England as appropriate.
It is important to follow our ‘Code of Conduct’ when collecting fossils or visiting any site. Please also read our ‘Terms and Conditions‘
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