Exmoor Group
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The Exmoor Group is a late
Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
to early
Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
lithostratigraphic Lithostratigraphy is a sub-discipline of stratigraphy, the geology, geological science associated with the study of stratum, strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are ...
group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic ide ...
(a sequence of
rock strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...
) in southwest
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
whose outcrop extends from
Croyde Croyde is a village on the west-facing coastline of North Devon, England. The village lies on the South West Coast Path near to Baggy Point, which is owned by the National Trust. It lies within the North Devon Coast Area of Outstanding Natura ...
in north
Devon Devon ( , historically known as Devonshire , ) is a ceremonial and non-metropolitan county in South West England. The most populous settlement in Devon is the city of Plymouth, followed by Devon's county town, the city of Exeter. Devon is ...
east across
Exmoor Exmoor is loosely defined as an area of hilly open moorland in west Somerset and north Devon in South West England. It is named after the River Exe, the source of which is situated in the centre of the area, two miles north-west of Simonsbath ...
to
Minehead Minehead is a coastal town and civil parish in Somerset, England. It lies on the south bank of the Bristol Channel, north-west of the county town of Taunton, from the boundary with the county of Devon and in proximity of the Exmoor National P ...
in west
Somerset ( en, All The People of Somerset) , locator_map = , coordinates = , region = South West England , established_date = Ancient , established_by = , preceded_by = , origin = , lord_lieutenant_office =Lord Lieutenant of Somerset , lord_ ...
. The group comprises the following formations (in stratigraphic order, i.e., the oldest at the base and the youngest at the top) the: *Pilton Mudstone Formation (Pilton Beds, Pilton Shales) *
Baggy Sandstones The Baggy Sandstones is a geologic formation in England. It preserves fossils dating back to the Devonian period. See also * List of fossiliferous stratigraphic units in England See also * Lists of fossiliferous stratigraphic units in Euro ...
Formation (Baggy Beds, Marwood Beds) *Upcott Slates Formation *Pickwell Down Sandstones Formation *Morte Slates Formation *Ilfracombe Slates Formation *Hangman Sandstone Formation (Hangman Grits) *Lynton Formation (Lynton Beds,
Lynton Slates The Lynton Slates is a geologic formation in England. It preserves fossils dating back to the Devonian period. See also * List of fossiliferous stratigraphic units in England See also * Lists of fossiliferous stratigraphic units in Europe ...
) Each of these divisions has been given different names by different authors in the past including those shown in brackets above. Some that had been classed as 'formations' (or even in one case as a '
group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic ide ...
') are now ' members'.


Lynton Formation

Extending east from Woody Bay, the Lynton Formation underlies the village from which the sequence is named and continues in a thin strip of country as far east as the hamlet of Oare. There is a small inlier of the Lynton Slates at the foot of the Quantock scarp at
Triscombe Crowcombe is a village and civil parish under the Quantock Hills in Somerset, England, southeast of Watchet, and from Taunton. The village has a population of 489. The parish covers the hamlets of Crowcombe Heathfield, Flaxpool, Halsway, Law ...
. The formation is composed of slates and siltstones together with some sandstone. Though its base is not seen, it is believed to be between 3–400 m thick. There are fossils of
brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...
s,
bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
s and bryozoans present, consistent with a shallow marine depositional environment. One of Devon and Exmoor's better known natural tourist attractions is
Valley of the Rocks The Valley of Rocks, sometimes called Valley of the Rocks, is a dry valley that runs parallel to the coast in north Devon, England, about to the west of the village of Lynton. It is a popular tourist destination, noted for its herd of fera ...
, a dry valley developed in this formation just to the west of
Lynton Lynton is a town on the Exmoor coast in the North Devon district in the county of Devon, England, approximately north-east of Barnstaple and west of Minehead, and close to the confluence of the West Lyn and East Lyn rivers. Governance Lynton ...
.


Hangman Sandstone Formation

The Hangman Sandstone forms the coastal outcrop east from Hangman Point as far as
Heddon's Mouth Heddon's Mouth is a rocky cove on the coast of North Devon, England, about a mile down the River Heddon from the Hunter's Inn. It is preserved for the nation by the National Trust. In previous times it was a popular venue for smugglers, but is no ...
and indeed the larger part of the cliffs eastwards again to Woody Bay. It again forms the coastal cliffs from Lynmouth Bay east to
Porlock Weir Porlock Weir is a harbour settlement approximately west of the inland village of Porlock, Somerset, England. "Porlock" comes from the Old English ''port'' '' loca'', meaning an enclosure near a harbour. Porlock Weir refers to the salmon stakes ...
, including
Foreland Point Foreland Point is a rocky headland in Devon near Lynmouth, and is the most northerly point along the Devon and Exmoor coast. The highest cliff is above the high tide, although the highest point of the entire headland is near Countisbury (a v ...
and Culbone Hill and also from Hurlstone Point to
Minehead Minehead is a coastal town and civil parish in Somerset, England. It lies on the south bank of the Bristol Channel, north-west of the county town of Taunton, from the boundary with the county of Devon and in proximity of the Exmoor National P ...
. The Porlock Ridge and Saltmarsh
Site of Special Scientific Interest A Site of Special Scientific Interest (SSSI) in Great Britain or an Area of Special Scientific Interest (ASSI) in the Isle of Man and Northern Ireland is a conservation designation denoting a protected area in the United Kingdom and Isle of ...
has a shingle ridge deposited during the
Holocene epoch The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
. Inland it forms the high ground east to
Dunkery Beacon Dunkery Beacon at the summit of Dunkery Hill is the highest point on Exmoor and in Somerset, England. It is also the highest point in southern England outside of Dartmoor. The sandstone hill rises to and provides views over the surrounding mo ...
and much of Croydon Hill. The larger part of the
Quantock Hills The Quantock Hills west of Bridgwater in Somerset, England, consist of heathland, oak woodlands, ancient parklands and agricultural land. They were England's first Area of Outstanding Natural Beauty, designated in 1956. Natural England have desi ...
are formed from the same strata. The Hangman Sandstone consist of several members which once enjoyed the status of 'formations'. These are (oldest base, youngest at top): *Little Hangman Member (Little Hangman Sandstones, Stringocephalus Beds, Little Hangman Formation) *Sherrycombe Member (Sherrycombe Beds, Sherrycombe Formation) *Rawns Member (Rawns Shales and Sandstone, Rawns Formation) *Trentishoe Member (Trentishoe Grits, Trentishoe Formation) *Hollowbrook Member (Hollowbrook Formation) Names in brackets indicate earlier names for the current members. The 'Stringocephalus Beds' and 'Sherrycombe Beds' were formerly grouped as the 'Upper Hangman Grits'. The thickness of the strata is estimated at between 1660 m and 2500 m; intense faulting and folding precludes an exact measurement being made. Consisting largely of sandstones but with some alternating shales and slates and some conglomerates, most of the formation is non-marine in origin. Plant and shell remains have been found though fossils are generally scarce within the formation. The sequence east of Lynmouth used to be referred to as the "Foreland Grits", and was thought to be somewhat older, and hence lower in the sequence, than the Hangman Grits The Trentishoe Member exhibits unusual deposition at the
Glenthorne Glenthorne () is a 13.3 hectare geological Site of Special Scientific Interest in the parish of Oare within the Exmoor National Park, on the border of Somerset and Devon, notified in 1989. Glenthorne is a Geological Conservation Review site be ...
Site of Special Scientific Interest A Site of Special Scientific Interest (SSSI) in Great Britain or an Area of Special Scientific Interest (ASSI) in the Isle of Man and Northern Ireland is a conservation designation denoting a protected area in the United Kingdom and Isle of ...
.


Ilfracombe Slates Formation

The formation comprises slates and limestones of marine origin and sandstones and slates with a shallow marine or
deltaic A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarel ...
origin. In the west, the Ilfracombe Slates are subdivided into (oldest at base, youngest at top): *Kentisbury Slates Member * Combe Martin Slates Member *Lester Slates-and-Sandstones Member *Wild Pear Slates Member The Wild Pear Slates are named from Wild Pear Beach at Combe Martin Bay where this sequence outcrops on the coast. The lower boundary of this sequence is a
thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...
which carries the slates up over the Hangman Grits. The overlying Lester Slates-and-Sandstones run from Widmouth Head, beneath the village of Combe Martin and on in a SSE direction to near
Parracombe Parracombe is a rural settlement south-west of Lynton, in Devon, England. It is situated in the Heddon Valley, on Exmoor. The population at the 2011 census was 293. A number Bronze Age barrows exist nearby, along with several other small ear ...
. The Combe Martin Slates in turn extend from Beacon Point at Hele in a narrowing outcrop to Pinkworthy Pond and beyond. The Kentisbury Slates form the coastal outcrop at
Ilfracombe Ilfracombe ( ) is a seaside resort and civil parish on the North Devon coast, England, with a small harbour surrounded by cliffs. The parish stretches along the coast from the 'Coastguard Cottages' in Hele Bay toward the east and along the ...
itself and extend inland via Kentisbury,
Challacombe Challacombe is a small village on the edge of the Exmoor National Park, in Devon, England. The village has a small general shop/Post Office and a single pub, the Black Venus. The village is on the B3358 road and is 5 miles west of Simonsbath. ...
and
Simonsbath Simonsbath () is a small village high on Exmoor in the English county of Somerset. It is the principal settlement in the Exmoor civil parish, which is the largest and most sparsely populated civil parish on Exmoor, covering nearly but with ...
towards Exford. In the east, the following subdivisions are identified. Some earlier (now formally obsolete) names are given in brackets afterwards: *Leighland Slates Member (Leighland Beds) *Cutcombe Slates Member *Avill Slates and Sandstones Member (Avill Group) In the Quantock Hills, the Avill Slates form the high ground of Lydeard Hill above
West Bagborough West Bagborough is a village and civil parish in Somerset, England, about north of Taunton in the Somerset West and Taunton district. In 2011 the village had a population of 358. The parish of West Bagborough lies on the south-west slopes of t ...
, together with the lower northeastern slopes of the range between
Aisholt Spaxton is a small village and civil parish on the Quantocks in the Sedgemoor district of Somerset, South West England. History Spaxton was part of the hundred of Cannington. The modern parish includes the ancient parishes of Aisholt and Cha ...
and
Holford Holford is a village and civil parish in West Somerset within the Quantock Hills Area of Outstanding Natural Beauty. It is located about west of Bridgwater and east of Williton, with a population of 392. The village is on the Quantock Greenway ...
. A
tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...
occurs within the Avill member on these eastern slopes at Keeper's Combe. The Cutcombe Slates form the ground immediately east of the Avill outcrop in this area whilst the Leighland Slates make up a band of higher ground between Cothelstone and Enmore with scattered outcrops extending north to
Nether Stowey Nether Stowey is a large village in the Sedgemoor district of Somerset, South West England. It sits in the foothills of the Quantock Hills (England's first Area of Outstanding Natural Beauty), just below Over Stowey. The parish of Nether Stowey ...
. Several limestone beds are named within the two upper members; oldest/lowermost first - the Rodhuish, Roadwater, Aisholt, Holwell and Leigh Barton limestones.


Morte Slates Formation

The Morte Slates are a series of silvery-grey to green coloured slates with some subordinate sandstone and siltstone. A well-developed cleavage has removed what fossils may have earlier been present in these one-time submarine muds. These rocks extend from
Morte Point Morte Point is a peninsula on the north west coast of Devon, England, belonging to the National Trust. To the east is the village of Mortehoe and to the south is the seaside resort of Woolacombe. In the summer season, tractor and trailer ride ...
, where they form the coast between
Woolacombe Woolacombe is a seaside resort on the coast of North Devon, England, which lies at the mouth of a valley (or "combe") in the parish of Mortehoe. The beach is long, sandy, gently sloping and faces the Atlantic Ocean near the western limit of the ...
and Flat Point, south-southeastwards through
West Down West Down is a small village and civil parish located in North Devon, England. It is to be found on the route between Braunton and Ilfracombe, north-west of Barnstaple. The village sits in a bowl in the hills at above sea level. In 2011 i ...
and Arlington then east to
Withypool Withypool (formerly Widepolle, Widipol, Withypoole) is a small village in Somerset, England, near the centre of Exmoor National Park and close to the border with Devon. The word Withy means "willow". The civil parish, known as Withypool and Hawk ...
. Further east the outcrop broadens to form the
Brendon Hills The Brendon Hills are a range of hills in west Somerset, England. The hills merge level into the eastern side of Exmoor and are included within the Exmoor National Park. The highest point of the range is Lype Hill at above sea level with a secon ...
and the rolling country around
Clatworthy Reservoir Clatworthy Reservoir is situated near Clatworthy in the Brendon Hills on the edge of the Exmoor National Park in west Somerset, England. It is run by Wessex Water and has a capacity of , supplying some 200,000 homes. It impounds the head waters ...
. The eastern extent of the main outcrop reaches the villages of Stogumber and Tolland. An outlier forms the southeastern part of the Quantock Hills between
Goathurst Goathurst is a small village and civil parish in the English county of Somerset, around 3 miles from the town of Bridgwater. The parish includes the hamlets of Andersfield and Huntstile. The village is on the route of the Samaritans Way South West ...
and
West Monkton West Monkton is a village and civil parish in Somerset, England, situated north east of Taunton in the Somerset West and Taunton district. The parish includes the hamlets of Monkton Heathfield, Bathpool, and Burlinch and the western parts of Co ...
. Over the centuries the Brendon Hills have been mined for minerals, notably
ironstone Ironstone is a sedimentary rock, either deposited directly as a ferruginous sediment or created by chemical replacement, that contains a substantial proportion of an iron ore compound from which iron (Fe) can be smelted commercially. Not to be con ...
from which iron is extracted for making
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
. During the 19th century this activity reached a peak with the
West Somerset Mineral Railway The West Somerset Mineral Railway was a standard gauge line in Somerset, England. Originally expected to be long its length as built was , with a branch to Raleigh's Cross Mine. The line's core purpose was to carry iron ore northwards from ...
, including an incline, being built to take the ore to
Watchet Watchet is a harbour town, civil parish and electoral ward in the county of Somerset, England, with a population in 2011 of 3,785. It is situated west of Bridgwater, north-west of Taunton, and east of Minehead. The town lies at the mouth of ...
from where it was sent to
Ebbw Vale Ebbw Vale (; cy, Glynebwy) is a town at the head of the valley formed by the Ebbw Fawr tributary of the Ebbw River in Wales. It is the largest town and the administrative centre of Blaenau Gwent county borough. The Ebbw Vale and Brynmawr con ...
for
smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ch ...
. The main mining operations ended when the mines were worked out towards the end of the 19th century.


Pickwell Down Sandstones Formation

The Pickwell Down Sandstones are red and brown sandstones with shales which extend from the hills of Pickwell Down and Woolacombe Down overlooking
Morte Bay Morte Bay is a bay on the northwest coast of Devon in southwest England. It stretches from Whiting Hole about 500m north of Baggy Point in the south to Morte Point in the north. At the back of the bay is a long stretch of beach known as Woolaco ...
east-southeastwards to Muddiford and
Bratton Fleming Bratton Fleming is a large village, civil parish and former manor near Barnstaple, in Devon, England. It lies a few miles west of Exmoor. The parish is surrounded, clockwise from the north, by the parishes of Challacombe, Brayford, Stoke River ...
. The outcrop pattern is shaped by a major east–west aligned syncline/anticline pair between
Brayford Brayford is a village and civil parish in Devon, England, situated about from South Molton and from Barnstaple. It lies on Exmoor and sits beneath open areas of common land. It is a small rural community and in the surrounding area are many ...
, where there is a stone quarry, and
Dulverton Dulverton is a small town and civil parish in west Somerset, England, near the border with Devon. The town had a population of 1,408 at the 2011 Census. The parish includes the hamlets of Battleton and Ashwick which is located approximately ...
. East of Dulverton the formation forms the prominent
Haddon Hill Haddon Hill is a prominent east–west aligned ridge in west Somerset, England, close to Hartford within the civil parish of Brompton Regis. It lies on the south-eastern fringe of Exmoor National Park though is separated from the Exmoor massif it ...
and extends via Heydon Hill as far east as the village of
Wiveliscombe Wiveliscombe (, ) is a small town and civil parish in Somerset, England, situated west of Taunton in the Somerset West and Taunton district. The town has a population of 2,893. The Square, fronted by several listed structures, held the former ...
. There are a number of former workings for iron,
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
and
manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
across the western part of its outcrop. A geomorphological survey at Anstey's Coombe showed that mining had taken place at the site during both the
Romano-British The Romano-British culture arose in Britain under the Roman Empire following the Roman conquest in AD 43 and the creation of the province of Britannia. It arose as a fusion of the imported Roman culture with that of the indigenous Britons, a ...
period and the 16th to 17th century.


Upcott Slates Formation

The Upcott Slates provide the coastal cliffs on the south side of Morte Bay and their narrow faulted outcrop continues east-southeastwards beneath
Georgeham Georgeham is a village and civil parish near Croyde, in North Devon. The appropriate electoral ward is termed Georgeham and Mortehoe with total population at the 2011 census of 3,748. Georgeham is an historic village lying close to some of t ...
and to Winsham and Marwood. The outcrop continues east via
Shirwell Shirwell is a village, civil parish and former manor in the local government district of North Devon, in the county of Devon, England. It was also formerly the name of a hundred of Devon. The village lies about 3.5 miles north-east of the town ...
to Little Bray, north of Brayford. Slightly offset by faulting to the south, it continues east to North Radworthy. A major east–west syncline in this area gives rise to an outcrop stretching southwest to East Buckland and then by virtue of a parallel anticline, stretching southeast then east to
North Molton North Molton is a village, parish and former manor in North Devon, England. The population of the parish in 2001 was 1,047, decreasing to 721 in the 2011 census. An electoral ward with the same name also exists. The ward population at the ce ...
. Subject to numerous northwest–southeast aligned faults, the outcrop can be followed via
Molland Molland is a small village, civil parish, dual ecclesiastical parish with Knowstone, located in the foothills of Exmoor in Devon, England. It lies within the North Devon local government district. At the time of the 2001 Census, the village ...
to east of Dulverton. The formation consists of slates varying in colour from buff through grey and green to purple. These rocks originated as muds laid down in swamps and freshwater lakes.


Baggy Sandstones Formation

The Baggy Sandstones form the headland of
Baggy Point Baggy Point is a headland in north Devon, England. It separates Croyde Bay and Morte Bay which includes the beaches of Woolacombe and Putsborough. There is evidence of human occupation from the Mesolithic era. It was used during World War II ...
and the faulted outcrop stretches away to the east north of Croyde, through Knowle to Stoke Rivers and
Brayford Brayford is a village and civil parish in Devon, England, situated about from South Molton and from Barnstaple. It lies on Exmoor and sits beneath open areas of common land. It is a small rural community and in the surrounding area are many ...
. Its outcrop wraps around a syncline/anticline fold pair in a reverse-S shape via East Buckland and parallels the outcrop of the Upcott Slates east to Dulverton. It is mapped as a distinguishable unit of the Exmoor Group as far as the Batherm valley, east of
Skilgate Skilgate is a village and civil parish east of Dulverton and west of Wiveliscombe in the Somerset West and Taunton district of Somerset, England. It has a population of 96. The parish, which covers an area of 866 ha, straddles the boundary of ...
. The formation consists of sandstones, siltstones and shales including some
feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldsp ...
and
mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...
rich units, variously of marine through brackish to freshwater origin. The outcrop forms a small yet prominent ridge along its outcrop.


Pilton Mudstone Formation

The Pilton Mudstones form the coast at Croyde Bay and form the headland at Saunton Down. The formation extends eastwards through Barnstaple to the Buckland area where due to a syncline/anticline pair, the surface outcrop divides. A thinner band of these strata continues east coincident with the valley of the River Yeo and the former railway to Brushford. The outcrop broadens once again forming the country around
Clayhanger The ''Clayhanger'' Family is a series of novels by Arnold Bennett, published between 1910 and 1918. Though the series is commonly referred to as a "trilogy", and the first three novels were published in a single volume, as ''The Clayhanger Famil ...
and
Waterrow Chipstable is a village and civil parish in Somerset, England, situated beside Heydon Hill west of Taunton in the Somerset West and Taunton district. The parish has a population of 309. The parish includes Raddington and Waterrow. History Th ...
before reaching its furthest east at
Kittisford Kittisford is a village and former parish and Manorialism, manor in Somerset, England, situated west of Taunton in the Taunton Deane district. It is now within the parish of Stawley. The parish Church of St Nicholas, Kittisford, Church of St Nic ...
and at Nunnington Park, south of Wiveliscombe. The formation consists of shales and siltstones along with bands of calcareous sandstone. Fossils include brachiopods and bivalves in the lower part of the formation, suggestive of a shallow marine depositional environment and, in its upper part,
trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...
s and
goniatite Goniatids, informally goniatites, are ammonoid cephalopods that form the order Goniatitida, derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago (around Eifelian stage). Goniatites (goniatitids) survi ...
s indicating deeper water conditions. The sandstones thicken to the east and have been worked in quarries between
Charles Charles is a masculine given name predominantly found in English language, English and French language, French speaking countries. It is from the French form ''Charles'' of the Proto-Germanic, Proto-Germanic name (in runic alphabet) or ''*k ...
and Brayford. Limestones occurring towards the top of the formation have also been worked in places. Whilst most of it is Devonian, the uppermost part of the formation is Carboniferous in age though the precise location of the boundary is difficult to determine.British Geological Survey 1982 ''Barnstaple'' England and Wales sheet 293 Solid & Drift Geology. 1:50,000 scale geological map (Keyworth, Nottingham: British Geological Survey)


References

{{Reflist, 2 Carboniferous System of Europe Devonian System of Europe Geological groups of the United Kingdom Geology of Somerset Geology of Devon