Lower Bostraze And Leswidden SSSI is a

biological 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 ...

, located on the

Penwith Peninsula Penwith (; kw, Pennwydh) is an area of Cornwall, England, United Kingdom, located on the peninsula of the same name. It is also the name of a former local government district, whose council was based in Penzance. The area is named after one ...

Cornwall Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...

, England, a little to the east of St Just, approximately 8 km west of

Penzance Penzance ( ; kw, Pennsans) is a town, civil parish and port in the Penwith district of Cornwall, United Kingdom. It is the most westerly major town in Cornwall and is about west-southwest of Plymouth and west-southwest of London. Situated ...

Geography

There are two discrete parts of this site – Lower Bostraze China Clay Works and Leswidden Block Works; together they are 23,000 m² in size. Lower Bostraze is located at , and Leswidden at . The site was notified as an SSSI in 1996. The site lies within the Cornwall Area of Outstanding Natural Beauty and the Penwith Heritage Coast and is partly within the West Penwith Environmentally Sensitive Area. The site has also been designated a

Special Area of Conservation A Special Area of Conservation (SAC) is defined in the European Union's Habitats Directive (92/43/EEC), also known as the ''Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora''. They are to protect the 220 habitats and ap ...

. Both parts of the site are underlain by the Land's End

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

, part of the

Cornubian batholith The Cornubian batholith is a large mass of granite rock, formed about 280 million years ago, which lies beneath much of Devon and Cornwall, the south-western peninsula of Great Britain. The main exposed masses of granite are seen at Dartmoor, Bo ...

. Zones within the granite, altered by kaolinisation, have been extensively worked for

china clay Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral ...

until recent years. China clay was discovered in the Balleswidden sett in 1880 and both areas are located within disused china clay workings, consisting of pits, benches, spoil tips and granitic debris with sparse vegetation cover.

Wildlife and ecology

The site's SSSI status is due to the presence of important populations of a very rare liverwort, the

Western Rustwort ''Marsupella profunda'', the western rustwort, is a liverwort native to Europe and known only from Portugal (Mainland, Azores and Madeira) and Great Britain (Cornwall) and has been sighted in the Canary Islands. It is a small reddish liverwort a ...

(''Marsupella profunda''). This species is rare in a British context (it is known from only two other locations in the UK:

St Austell Clay Pits St Austell Clay Pits, (Cornwall, England, UK,) are a group of locations within active china clay quarries that form a single Site of Special Scientific Interest (SSSI) and Special Area of Conservation, noted for its biological characteristics. ...

and

Tregonning Hill Tregonning Hill is the westerly of two granite hills overlooking Mount's Bay in west Cornwall, United Kingdom, the other being Godolphin Hill. They are approximately west of the town of Helston. The Plymouth chemist William Cookworthy mixed chin ...

, both within Cornwall). However, it is also internationally rare, being known only from

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

, the

Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...

, the

Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

and

Madeira ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

; throughout this range it is a rare species. At Lower Bostraze and Leswidden, Western Rustwort is generally found growing on micaceous or clay waste substrates which are flat or gently sloping. Some patches occur on granitic rocks, usually where these are soft or crumbling. It appears to be a

pioneer species Pioneer species are hardy species that are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by wildfire. Pioneer flora Some lichens grow on rocks without soil, so m ...

, the largest populations being found on surfaces showing the early stages of

colonisation Colonization, or colonisation, constitutes large-scale population movements wherein migrants maintain strong links with their, or their ancestors', former country – by such links, gain advantage over other inhabitants of the territory. When ...

by other

bryophyte The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. Bryophyta s.s. consists of the mosses only. They are characteristically limited in ...

s and by

vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They al ...

s. The conservation charity

Plantlife Plantlife is the international conservation membership charity working to secure a world rich in wild plants and fungi. It is the only UK membership charity dedicated to conserving wild plants and fungi in their natural habitats and helping peo ...

designated the St Just Moors, part of this SSSI, an

Important Plant Area Important Plant Areas (IPA) is a programme set up in the UK, by the organisation Plantlife, to provide a framework for identifying and maintaining the richest sites for plant life, possibly within existing protected areas; though the protection of ...

for the occurrence of Western Rustwort and the

green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

desmids Desmidiales, commonly called desmids (''Gr.'' ''desmos'', bond or chain), are an order in the Charophyta, a division of green algae in which the land plants (Embryophyta) emerged. Or in other words, Desmid, (order Desmidiales), order of singl ...

History

The

works at Leswidden started in 1886 or 1887 and were suspended in April, 1887 due to problems with water supply.

Toponymy

The meaning of Bostraze is "dwelling in a flat-bottomed valley". There is a place called Bostrase in the parish of St Hilary (with the same meaning). The meaning of Leswidden is "white / fair ruin".

Craig Weatherhill Craig Weatherhill (1950 or 1951 – 18 or 19 July 2020) was a Cornish antiquarian, novelist and writer on the history, archaeology, place names and mythology of Cornwall. Weatherhill attended school in Falmouth, where his parents ran a sports ...

(2009) ''A Concise Dictionary of Cornish Place-Names''. Westport, Co. Mayo: Evertype ; pp. 24 & 46

References

{{SSSIs Cornwall biological, state=collapsed Penwith Sites of Special Scientific Interest in Cornwall Sites of Special Scientific Interest notified in 1996 Special Areas of Conservation in Cornwall