The Ercall is a small hill in

Shropshire Shropshire (; alternatively Salop; abbreviated in print only as Shrops; demonym Salopian ) is a landlocked historic county in the West Midlands region of England. It is bordered by Wales to the west and the English counties of Cheshire to ...

, England, between

The Wrekin The Wrekin is a hill in east Shropshire, England. It is located some five miles (8 km) west of Telford, on the border between the unitary authorities of Shropshire and Telford and Wrekin. Rising above the Shropshire Plain to a height of 4 ...

and

Wellington Wellington ( mi, Te Whanganui-a-Tara or ) 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 second-largest city in New Zealand by metr ...

. It is an internationally important geological site, part of The Wrekin and The Ercall Site of Special Scientific Interest (SSSI). The hill is managed by

Shropshire Wildlife Trust The Shropshire Wildlife Trust is a wildlife trust covering the geographic county of Shropshire, England. Nature reserves The trust cares for, or is associated with, 42 nature reserves (plus its headquarters in Shrewsbury – see next section) ...

and includes 540 million year old ripple beds and ancient pre-Cambrian lava flows in exposed quarries.

Quartzite Quartzite is a hard, non- foliated metamorphic rock which 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 tec ...

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 23-mile (37 km) 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&nbs ...

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 insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group comprise ...

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, is decorative. There are many kinds of walls, including: * Walls in buildings that form a fundamental part of the sup ...

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

oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...

trees predominate. Acidic soils support such plants as

bilberry Bilberries (), or sometimes European blueberries, are a primarily Eurasian species of low-growing shrubs in the genus ''Vaccinium'' (family Ericaceae), bearing edible, dark blue berries. The species most often referred to is '' Vaccinium myrtill ...

, climbing corydalis and

heath bedstraw ''Galium saxatile'' or heath bedstraw is a plant species of the genus ''Galium''. 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 , and flower ...

. 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 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 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 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 surface of a rocky planet or moon. More than 90 ...

(extrusive). There is a significant alteration about the contact between the two rocks. The dolerite dyke was emplaced into the Uriconian Rhyolite. The rhyolitic rocks themselves are representative of explosive volcanic centres to the west of this site and beyond the Church Stretton 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 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 is a British variety store chain founded in 1990. It once sold most items at the single price of £1, including clearance items and proprietary brands. The first pilot store opened in December 1990 following numerous rejections by ...

launched a rival chocolate bar to the

Toblerone Toblerone ( , ) is a Swiss chocolate brand produced in Bern. Toblerone is known for its distinctive shape, a series of joined triangular prisms and lettering engraved in the chocolate. Since 2012, the brand has been owned by US company Mondele ...

, which is manufactured by

Mondelēz Mondelez International, Inc. ( ), often styled Mondelēz, is an American multinational confectionery, food, holding and beverage and snack food company based in Chicago. Mondelez has an annual revenue of about $26 billion and operates in ...

. Poundland's bar, Twin Peaks, takes the design of its shape from The Ercall and Wrekin hills. Poundland is based in the

West Midlands West or Occident is one of the four cardinal directions or points of the compass. It is the opposite direction from east and is the direction in which the Sun sets on the Earth. Etymology The word "west" is a Germanic word passed into some ...

, and its founder, Steve Smith, lives near

Bridgnorth Bridgnorth is a town 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 2011 Census was 12,079. Histor ...

in Shropshire.

References

{{coord, 52.68291, -2.52952, type:landmark_region:GB_source:enwiki-osgb36(SJ643096), display=title Ercall, The Ercall, The Sites of Special Scientific Interest in Shropshire E