The Ercall is a small hill in

Shropshire Shropshire (; abbreviated SalopAlso used officially as the name of the county from 1974–1980. The demonym for inhabitants of the county "Salopian" derives from this name.) is a Ceremonial counties of England, ceremonial county in the West M ...

, England, between

The Wrekin The Wrekin ( ) is a hill in east Shropshire, England. It is located some west of Telford, on the border between the unitary authorities of Shropshire Council, Shropshire and Telford and Wrekin. Rising above the Shropshire Plain to a height of ...

and

Wellington Wellington is the capital city of New Zealand. It is located at the south-western tip of the North Island, between Cook Strait and the Remutaka Range. Wellington is the third-largest city in New Zealand (second largest in the North Island ...

. It is an internationally important geological site, part of The Wrekin and The Ercall

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 ...

(SSSI). The hill is managed by Shropshire Wildlife Trust and includes 540 million year old ripple beds and ancient

pre-Cambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

lava flows in exposed quarries.

Quartzite Quartzite is a hard, non- foliated metamorphic rock that was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tecton ...

from the neighbouring Wrekin is also visible. The Ercall bears the marks of extensive quarrying, although the quarries are now disused, safe and open to the public. When the

M54 motorway The M54 is a east-west motorway in the counties of Shropshire and Staffordshire, England. It is also referred to as the Telford motorway, after the road's primary westbound destination, the town of Telford. It cost £65 million to construc ...

was constructed in 1974, the road was built through the northern end of the hill.

Flora and fauna

The woods of the forest are important for various

butterfly Butterflies are winged insects from the lepidopteran superfamily Papilionoidea, characterized by large, often brightly coloured wings that often fold together when at rest, and a conspicuous, fluttering flight. The oldest butterfly fossi ...

species. In the summer, the Ercall Woods which line the hill are a favourite habitat for the speckled wood and during spring when the forest is laden with bluebells, the dingy skipper can arrive in great numbers. The exposed quarries are popular with other butterfly species, including the green hairstreak and

wall A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or serves a decorative purpose. There are various types of walls, including border barriers between countries, brick wal ...

, which like to bask in sheltered spots. On the upper slopes of the hill tall

oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

trees predominate. Acidic soils support such plants as

bilberry Bilberries () are Eurasian low-growing shrubs in the genus ''Vaccinium'' in the flowering plant family Ericaceae that bear edible, dark blue berries. They resemble but are distinct from North American blueberries. The species most often referre ...

, climbing corydalis and

heath bedstraw ''Galium saxatile'' or heath bedstraw is a species of flowering plant in the family Rubiaceae. It is related to cleavers. ''Galium saxatile'' is a perennial mat-forming herb, found on grassland, moors, heaths and woods. It can reach a height of ...

. The green woodpecker is also present in the wood

Access

The hill is accessed in much the same way as

nearby; exit the

at J7 (last exit) or the last junction of the A5 road (Great Britain), A5 from

Shrewsbury Shrewsbury ( , ) is a market town and civil parish in Shropshire (district), Shropshire, England. It is sited on the River Severn, northwest of Wolverhampton, west of Telford, southeast of Wrexham and north of Hereford. At the 2021 United ...

before it becomes the M54. From there The Wrekin is signposted; follow this road until you reach The Wrekin, then follow the sign for the Buckatree Hotel. There is a small car park across the road from this pub/hotel, and the entrance is clearly visible.

Geology

The Ercall Quarries are a SSSI and therefore care needs to be exercised when investigating this area. Upon entering the quarry from the main entrance near

one encounters an old quarry with many distinctive geological features evident

This is the first quarry that is apparent in the Ercall, it comprises Uriconian Volcanic deposits of

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of t ...

age. Such volcanic deposits are noted to have been bimodal and potentially intraplate possibly induced by (and therefore close to a) subduction zone and possibly in an island arc setting.P. J. Brenchley, P. F. Rawson ''The Geology of England and Wales'', 2006, 2nd Ed The flow banding and fine to medium grained appearance of the deposit suggests a fairly rapid cooling event and appears to have been deposited in a submerged environment. In all likelihood, during such events the depositional environment would fluctuate between submarine and subaerial as sea-floor levels will have fluctuated as well as eustatic sea-levels.W. Compston, A. E. Wright, P. Toghill, "Dating the Late Precambrian volcanicity of England and Wales", ''Journal of the Geological Society'', 2002; v.159; pp 323–339 On the right had side of the picture (running vertical) a dark grey doleritic dyke is evident. The dyke trends at approximately 65 degrees.

Dolerite Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...

is intrusive and is relative to

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

(extrusive). There is a significant alteration about the contact between the two rocks. The dolerite dyke was emplaced into the Uriconian

Rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

. The rhyolitic rocks themselves are representative of explosive volcanic centres to the west of this site and beyond the

Church Stretton Church Stretton is a market town and civil parish in Shropshire, England, south of Shrewsbury and north of Ludlow. The population in 2011 was 4,671.

lineament. There is a clear distinction between the tuffaceous rocks of the Uriconican Volcanics (dark brown/black/grey) and the intrusive

granophyre Granophyre ( ; from ''granite'' and ''porphyry'') is a subvolcanic rock that contains quartz and alkali feldspar in characteristic angular intergrowths such as those in the accompanying image. The texture is called granophyric. The texture can b ...

which is pink. The relationship between the Ercall Granophyre and the Uriconian is also clearly evident as the Granophyre intrudes the Volcanic rocks and is therefore younger. The Ercall Granophyre is overlain by shallow dipping

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

rocks (in relation to the steeply dipping Uriconian volcanics) which contain Atdabanian fossils. The

Granophyre Granophyre ( ; from ''granite'' and ''porphyry'') is a subvolcanic rock that contains quartz and alkali feldspar in characteristic angular intergrowths such as those in the accompanying image. The texture is called granophyric. The texture can b ...

is dated at 560+/-1Ma and is thought to be related to the volcanic events in the area.Tucker, R.D. & Pharaoh, T.C., ''U-Pb Zircon ages for Late Precambrian – early Palaeozoic plate tectonics evolution of England and Wales'', Journal of the Geological Society of London 1991; v.148; pp435-443 The thermal expansion of the area is likely to have assisted the formation of a sedimentary basin in which such volcaniclastic sediments accrued and were later folded. This has given rise to the steeply dipping sequences exposed at places such as the Forest Glen car park. The folding event is thought to be contemporaneous with uplift and a date of 526+/-28Ma has been put forward for this.

Twin Peaks chocolate bar

In 2017, the discount retailer

Poundland Poundland Limited is a British variety store chain founded by Dave Dodd and Steven Smith in 1990, originally selling all of its items at the single price of £1. The retailer grew from a single location in Burton upon Trent, opening its hund ...

launched a rival chocolate bar to the

Toblerone Toblerone ( , ) is a Swiss chocolate brand owned by Mondelez International (originally Kraft Foods Inc, Kraft Foods). Until 2022, it was produced exclusively in Bern, Switzerland, when a smaller, limited part of the portfolio began production i ...

, which is manufactured by Mondelēz. Poundland's bar, Twin Peaks, takes the design of its shape from The Ercall and Wrekin hills. Poundland is based in the West Midlands, and its founder, Steve Smith, lives near

Bridgnorth Bridgnorth is a market town and civil parish in Shropshire, England. The River Severn splits it into High Town and Low Town, the upper town on the right bank and the lower on the left bank of the River Severn. The population at the United Kingd ...

in Shropshire.

References

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