Outcrop of Rock on Brean Down
This rock is made of carboniferous limestone, which is a collective term for the succession of limestones which occur widely throughout Great Britain and Ireland which were deposited during the Dinantian Epoch of the Carboniferous Period. These rocks formed between 363 and 325 million years ago. Within England and Wales, the entire limestone succession which includes subordinate mudstones and some thin sandstones is known as the Carboniferous Limestone Supergroup.
Carboniferous Limestone is a sedimentary rock made of calcium carbonate. It is generally light-grey in colour, and is hard. It was formed in warm, shallow tropical seas teeming with life. The rock is made up of the shells and hard parts of millions of sea creatures, some up to 30 cm in length, encased in carbonate mud. Fossil corals, brachiopods and crinoids are very much in evidence as components of Carboniferous Limestone; indeed the rock is full of fossils.
Carboniferous Limestone has horizontal layers (beds) with bedding planes, and vertical joints. These joints are weaknesses in the rock, which are exploited by agents of both denudation and weathering. They also lead to the most important characteristic of Carboniferous Limestone - its permeability. Water seeps through the joints in the limestone. This creates a landscape that lacks surface drainage but which has all manner of characteristic surface and subsurface features. The Carboniferous Limestone has been folded and faulted by massive Earth movements which can be seen by the fact that the rocks are now above sea-level and no longer horizontal. The rocks generally dip (slope) gently eastwards and, in some places, clear folds in the rock can be seen especially at the Great Orme and Bryn Alyn (Denbighshire).
These rocks were deposited as marine sediments in three distinct ‘provinces’ separated by contemporary landmasses. One of these landmasses was the Wales-London-Brabant Massif, an east-west aligned belt of land stretching through central Wales and the English Midlands to East Anglia and on into Belgium. The limestones deposited to its south form this distinct South Wales-Mendip province which extends from Pembrokeshire in the west through southern Carmarthenshire, Glamorgan and south Powys to Monmouthshire, Gloucestershire and north Somerset. These rocks continue eastwards at depth beneath Oxfordshire.
The larger part of the Mendip Hills are formed from Carboniferous Limestone, showing notable geomorphological features, including Cheddar Gorge, Burrington Combe and the showcave of Wookey Hole. The Avon Gorge west of Bristol and the coastal cliffs at Clevedon and Weston-super-Mare are cut in this rock. The limestone islands of Flat Holm and Steep Holm are prominent in views across the mouth of the Severn Estuary.
Brean Down is a promontory off the coast of Somerset standing 320 feet (98 m) high and extending 1.5 miles (2 km) into the Bristol Channel at the eastern end of Bridgwater Bay between Weston-super-Mare and Burnham-on-Sea. It is a continuation of the Mendip Hills, and two further continuations are the small islands of Steep Holm and Flat Holm.
It is now owned by the National Trust, and is rich in wildlife, history and archaeology. It is a Site of Special Scientific Interest. There are steep cliffs and, at its seaward point, a Brean Down Fort built in 1865 and then re-armed in the Second World War.
There is evidence of a shrine at Brean Down dating from pre-Roman times which was re-established as a Romano-Celtic Temple in the mid-4th century and probably succeeded by a small late-4th century Christian oratory. Several Roman finds including gold coins of Augustus, Nero, and Drusus, two silver denarii of Vespasian and a Roman cornelian ring were found at the site during quarrying.
There is also evidence of an Iron age hill fort and prehistoric barrows and field systems. One tradition holds that the bodies of the knights responsible for the assassination of Thomas Becket were returned to the island and buried there.
Brean Down Fort was built on the headland between 1864 and 1871 on the recommendations of the 1859 Royal Commission. It was the most southerly of a chain of defences across the Bristol Channel, protecting the access to Bristol and Cardiff. On the outbreak of World War II the fort was rearmed with two 6" ex-naval guns and machine gun posts were built on the Down. During WWII the site was also used as a test launch site for rockets and experimental weapons, and a large concrete arrow was constructed on the down to direct bombers to the practice range.
In the 1860s plans were laid for a deep water harbour on the northern shore of Brean Down. The foundation stones of the pier were laid, but the project was later abandoned after a large storm destroyed the foundations.
In 1897, following wireless transmissions from Lavernock Point in Wales and Flat Holm, Guglielmo Marconi moved his equipment to Brean Down and set a new distance record for wireless transmission over open sea.
In 1952 the former Axbridge Rural District Council gave the down to the National Trust to celebrate the "Festival of Britain". After restoring the fort, Sedgemoor District Council gave this to the trust as well in 2002.
Various proposals have been put forward to construct a Severn Barrage for tidal electricity production from Brean Down to Lavernock Point in south Wales.
The nationally rare White Rock-rose (Helianthemum appenninum) is a common species at the site, occurring in abundance on the upper reaches of the grassy south-facing slopes. Some of the broomrapes growing here which were originally thought to be Oxtongue Broomrape (Orobanche artemisiae-campestriae) are now no longer believed to be this species, but atypical specimens of Ivy Broomrape (O. hederae)
Other plants on the southern slopes include the Somerset Hair Grass, wild thyme, Horseshoe Vetch and birds-foot-trefoil. The northern side is dominated by Bracken, bramble, privet, hawthorn, cowslips and bell heather.
The birds seen on Brean Down include Peregrine falcon, jackdaw, kestrel, collared and stock doves, whitethroat, linnet, stonechat, dunnock, rock pipit and — in 2007 - Britain's first and only Atlantic Yellow-nosed Albatross. There are also several species of butterfly including; Chalkhill blue, Dark Green Fritillary, Meadow Brown, Marbled White, small heath, and common blue.
en.wikipedia.org/wiki/Carboniferous_Limestone
Outcrop of Rock on Brean Down
This rock is made of carboniferous limestone, which is a collective term for the succession of limestones which occur widely throughout Great Britain and Ireland which were deposited during the Dinantian Epoch of the Carboniferous Period. These rocks formed between 363 and 325 million years ago. Within England and Wales, the entire limestone succession which includes subordinate mudstones and some thin sandstones is known as the Carboniferous Limestone Supergroup.
Carboniferous Limestone is a sedimentary rock made of calcium carbonate. It is generally light-grey in colour, and is hard. It was formed in warm, shallow tropical seas teeming with life. The rock is made up of the shells and hard parts of millions of sea creatures, some up to 30 cm in length, encased in carbonate mud. Fossil corals, brachiopods and crinoids are very much in evidence as components of Carboniferous Limestone; indeed the rock is full of fossils.
Carboniferous Limestone has horizontal layers (beds) with bedding planes, and vertical joints. These joints are weaknesses in the rock, which are exploited by agents of both denudation and weathering. They also lead to the most important characteristic of Carboniferous Limestone - its permeability. Water seeps through the joints in the limestone. This creates a landscape that lacks surface drainage but which has all manner of characteristic surface and subsurface features. The Carboniferous Limestone has been folded and faulted by massive Earth movements which can be seen by the fact that the rocks are now above sea-level and no longer horizontal. The rocks generally dip (slope) gently eastwards and, in some places, clear folds in the rock can be seen especially at the Great Orme and Bryn Alyn (Denbighshire).
These rocks were deposited as marine sediments in three distinct ‘provinces’ separated by contemporary landmasses. One of these landmasses was the Wales-London-Brabant Massif, an east-west aligned belt of land stretching through central Wales and the English Midlands to East Anglia and on into Belgium. The limestones deposited to its south form this distinct South Wales-Mendip province which extends from Pembrokeshire in the west through southern Carmarthenshire, Glamorgan and south Powys to Monmouthshire, Gloucestershire and north Somerset. These rocks continue eastwards at depth beneath Oxfordshire.
The larger part of the Mendip Hills are formed from Carboniferous Limestone, showing notable geomorphological features, including Cheddar Gorge, Burrington Combe and the showcave of Wookey Hole. The Avon Gorge west of Bristol and the coastal cliffs at Clevedon and Weston-super-Mare are cut in this rock. The limestone islands of Flat Holm and Steep Holm are prominent in views across the mouth of the Severn Estuary.
Brean Down is a promontory off the coast of Somerset standing 320 feet (98 m) high and extending 1.5 miles (2 km) into the Bristol Channel at the eastern end of Bridgwater Bay between Weston-super-Mare and Burnham-on-Sea. It is a continuation of the Mendip Hills, and two further continuations are the small islands of Steep Holm and Flat Holm.
It is now owned by the National Trust, and is rich in wildlife, history and archaeology. It is a Site of Special Scientific Interest. There are steep cliffs and, at its seaward point, a Brean Down Fort built in 1865 and then re-armed in the Second World War.
There is evidence of a shrine at Brean Down dating from pre-Roman times which was re-established as a Romano-Celtic Temple in the mid-4th century and probably succeeded by a small late-4th century Christian oratory. Several Roman finds including gold coins of Augustus, Nero, and Drusus, two silver denarii of Vespasian and a Roman cornelian ring were found at the site during quarrying.
There is also evidence of an Iron age hill fort and prehistoric barrows and field systems. One tradition holds that the bodies of the knights responsible for the assassination of Thomas Becket were returned to the island and buried there.
Brean Down Fort was built on the headland between 1864 and 1871 on the recommendations of the 1859 Royal Commission. It was the most southerly of a chain of defences across the Bristol Channel, protecting the access to Bristol and Cardiff. On the outbreak of World War II the fort was rearmed with two 6" ex-naval guns and machine gun posts were built on the Down. During WWII the site was also used as a test launch site for rockets and experimental weapons, and a large concrete arrow was constructed on the down to direct bombers to the practice range.
In the 1860s plans were laid for a deep water harbour on the northern shore of Brean Down. The foundation stones of the pier were laid, but the project was later abandoned after a large storm destroyed the foundations.
In 1897, following wireless transmissions from Lavernock Point in Wales and Flat Holm, Guglielmo Marconi moved his equipment to Brean Down and set a new distance record for wireless transmission over open sea.
In 1952 the former Axbridge Rural District Council gave the down to the National Trust to celebrate the "Festival of Britain". After restoring the fort, Sedgemoor District Council gave this to the trust as well in 2002.
Various proposals have been put forward to construct a Severn Barrage for tidal electricity production from Brean Down to Lavernock Point in south Wales.
The nationally rare White Rock-rose (Helianthemum appenninum) is a common species at the site, occurring in abundance on the upper reaches of the grassy south-facing slopes. Some of the broomrapes growing here which were originally thought to be Oxtongue Broomrape (Orobanche artemisiae-campestriae) are now no longer believed to be this species, but atypical specimens of Ivy Broomrape (O. hederae)
Other plants on the southern slopes include the Somerset Hair Grass, wild thyme, Horseshoe Vetch and birds-foot-trefoil. The northern side is dominated by Bracken, bramble, privet, hawthorn, cowslips and bell heather.
The birds seen on Brean Down include Peregrine falcon, jackdaw, kestrel, collared and stock doves, whitethroat, linnet, stonechat, dunnock, rock pipit and — in 2007 - Britain's first and only Atlantic Yellow-nosed Albatross. There are also several species of butterfly including; Chalkhill blue, Dark Green Fritillary, Meadow Brown, Marbled White, small heath, and common blue.
en.wikipedia.org/wiki/Carboniferous_Limestone