Teän ( , sometimes written ''Tean'' without the
diaeresis; ) is an uninhabited island to the north of the
Isles of Scilly
The Isles of Scilly ( ; ) are a small archipelago off the southwestern tip of Cornwall, England. One of the islands, St Agnes, Isles of Scilly, St Agnes, is over farther south than the most southerly point of the Great Britain, British mainla ...
archipelago between
Tresco Tresco may refer to:
* Tresco, Elizabeth Bay, a historic residence in New South Wales, Australia
* Tresco, Isles of Scilly, an island off Cornwall, England, United Kingdom
* Tresco, Victoria, a town in Victoria, Australia
* a nickname referring t ...
, to the west, and
St Martin's, to the east. Approximately in area, the island consists of a series of
granite
Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, 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 coo ...
tors with the highest point, Great Hill, rising to at its eastern end. The low-lying land is overlain with
glacial till
image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
and
outwash gravels with
glacial erratics
A glacial erratic is a glacially deposited rock (geology), rock differing from the type of country rock (geology), rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by gla ...
abundant on the north coast beaches, which indicates the southern limit of outwash from an ice sheet
for which it is designated a
Geological Conservation Review
The Geological Conservation Review (GCR) is produced by the UK's Joint Nature Conservation Committee. It is designed to identify those sites of national and international importance needed to show all the key scientific elements of the geological ...
site.
There is evidence of occupation from the
Bronze Age
The Bronze Age () was a historical period characterised principally by the use of bronze tools and the development of complex urban societies, as well as the adoption of writing in some areas. The Bronze Age is the middle principal period of ...
to the early 19th century and the island was still being grazed in 1945.
[Parslow, R. (2007) ''The Isles of Scilly''. ]New Naturalist
The New Naturalist Library (also known as ''The New Naturalists'') is a series of books published by Collins in the United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Br ...
Library. London: HarperCollins An early Christian chapel exists on the island; it was possibly dedicated to a saint called Theon.
The island lies within both the Isles of Scilly
Heritage Coast
A heritage coast is a strip of coastline in England and Wales, the extent of which is defined by agreement between the relevant statutory national agency and the relevant local authority. Such areas are recognised for their natural beauty, wildlife ...
and the Isles of Scilly
Area of Outstanding Natural Beauty
An Area of Outstanding Natural Beauty (AONB; , AHNE) is one of 46 areas of countryside in England, Wales, or Northern Ireland that has been designated for conservation due to its significant landscape value. Since 2023, the areas in England an ...
. It is managed by the
Isles of Scilly Wildlife Trust
The Isles of Scilly Wildlife Trust, formed in 1985, is a Wildlife Trust covering the Isles of Scilly, a group of islands off the coast of Cornwall. It became the 46th member of The Wildlife Trusts in 2001 and is dedicated to ensuring that the a ...
, which has a
Higher Level Stewardship (HLS) agreement.
History
The coastline of Teän consists of a number of bays and sandy beaches that link to offshore rocks and carns at low tide. The western part of the island has low-lying ground linking granite carns; field boundaries from 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, ...
period can be seen at extreme low tides.
One of the carns, Old Man, has an early structure, a
Bronze Age
The Bronze Age () was a historical period characterised principally by the use of bronze tools and the development of complex urban societies, as well as the adoption of writing in some areas. The Bronze Age is the middle principal period of ...
entrance grave, as does Great Hill in the east of the island. Roman type brooches have been found in a grave on Old Man. Sixteen early Christian graves have been found under the east wall of St Theona's chapel which was built later on top of the graves. There was probably an earlier wooden chapel.
[Reid, N. (2007) ''Isles of Scilly Guidebook''.]
A Parliamentary survey of 1652 reported one man living in a ruined house on the island; in 1684, there was a thatched cottage between East Porth and West Porth that belonged to a Mr Nance, who is reputed to have introduced
kelp
Kelps are large brown algae or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...
burning to Scilly. Kelp burning provides
sodium carbonate
Sodium carbonate (also known as washing soda, soda ash, sal soda, and soda crystals) is the inorganic compound with the formula and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water ...
for glass making and the practice continued in the islands until 1835. Kelp burning only produces 2–3 percent sodium carbonate; during the 19th century more efficient commercial and industrial methods ended the practice locally. Rights to areas of kelp were allocated to families; in 1787 Thomas Woodcock, his son and James Ashford (all of St Martin's) were accused of "having trespassed on his (Nance's) preserves". After the hearing, the court decided that the cutting of ore-weed and the making of kelp on Teän was the prescriptive right of Nance, and the trespassers were fined 2s 6d each.
His family continued to live on Teän for several more generations; by 1717 there were ten people living on the island, but in 1752
William Borlase only saw fields of corn and ruined buildings.
[ In the 19th century Woodley reported occasional occupation, a few acres of cultivation and sheep grazing; while a 1919 guide book reported just a rabbit warren. Cattle were still being grazed in 1945.
]
Natural history
The island was first notified as a 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 ...
in 1971 and re-notified in 1986 under the 1981 Act. The SSSI was last assessed on 8 September 2009 and was found to be favourable. The assessment found that the vascular plant assemblage was all recorded apart from four-leaved allseed ''Polycarpon tetraphyllum
''Polycarpon tetraphyllum'', commonly known as four-leaved allseed (also fourleaf allseed or fourleaf manyseed), is a plant of the family Caryophyllaceae. An annual herb growing to 15 cm in height, it is found on sandy soils, in coastal area ...
''. A key issue was lack of management for orange bird's-foot ('' Ornithopus pinnatus''), which needs short turf and can be addressed with the HLS agreement held by the Isles of Scilly Wildlife Trust. All of the land designated as the Teän Site of Special Scientific Interest is owned by the Duchy of Cornwall
A duchy, also called a dukedom, is a country, territory, fief, or domain ruled by a duke or duchess, a ruler hierarchically second to the king or queen in Western European tradition.
There once existed an important difference between "sovereign ...
.
Flora
Human activity continued until relatively recently and is evident with 8 ha of the island surrounded by hedges and once cultivated. This area, with deeper soils, is dominated by bracken (''Pteridium aquilinum
''Pteridium aquilinum'', commonly called bracken, brake, pasture brake, common bracken, and also known as eagle fern, is a species of fern occurring in temperate and subtropical regions in both hemispheres. Originally native to Eurasia and North ...
'') and still has relic pasture plants such as rye grass ('' Lolium perenne''), red clover (''Trifolium pratense
''Trifolium pratense'' (from Latin prātum, meaning meadow), red clover, is a herbaceous species of flowering plant in the bean family, Fabaceae. It is native to the Old World, but planted and naturalised in many other regions.
Description
...
''), hop trefoil ('' Trifolium campestre'') and black knapweed ('' Centaurea nigra''). The maritime grassland around St Helen's Porth, and on the south coast, has abundant thrift ('' Armeria maritima'') and sea campion ('' Silene maritime''), and near Clodgie Point orange bird's-foot occurs. The dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...
grassland area behind East and West Porth is important for the very rare dwarf pansy ('' Viola kitaibeliana''). The summit of Great Hill has a small area of lowland heath.
Rare plants
* Shore dock (''Rumex rupestris
The docks and sorrels, genus ''Rumex'', are a genus of about 200 species of Annual plant, annual, Biennial plant, biennial, and perennial plant, perennial herbs in the buckwheat family, Polygonaceae.
Members of this genus are very common perennia ...
'') was first recorded in 1984 and was still there in 2005. It is a Biodiversity Action Plan species and one of the primary reasons why the Isles of Scilly is 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 ...
(SAC).
* Four-leaved allseed (''Polycarpon tetraphyllum
''Polycarpon tetraphyllum'', commonly known as four-leaved allseed (also fourleaf allseed or fourleaf manyseed), is a plant of the family Caryophyllaceae. An annual herb growing to 15 cm in height, it is found on sandy soils, in coastal area ...
'') was last recorded in 1990.
* Saltwort ('' Salsola kali'') was recorded in 2009. It was once found on most sandy beaches in Scilly but is now a rare plant; its previous record on Scilly was 2004 on Samson
SAMSON (Software for Adaptive Modeling and Simulation Of Nanosystems) is a computer software platform for molecular design being developed bOneAngstromand previously by the NANO-D group at the French Institute for Research in Computer Science an ...
.
Fauna
The only mammals found on Teän are the Brown Rat (''Rattus norvegicus
''Rattus'' is a genus of muroid rodents, all typically called rats. However, the term rat can also be applied to rodent species outside of this genus.
Species and description
The best-known ''Rattus'' species are the black rat (''R. rattus' ...
'') and the House Mouse (''Mus musculus
The house mouse (''Mus musculus'') is a small mammal of the rodent family Muridae, characteristically having a pointed snout, large rounded ears, and a long and almost hairless tail. It is one of the most abundant species of the genus ''Mus (genu ...
''). Rabbit ('' Oryctolagus cuniculus'') may be extinct. With no grazing animals on the island, plants that prefer a short sward such as orange bird's-foot may become extinct. In 1850 J. W. North reported that Teän "is a preserve of white rabbits"! Scilly Shrew ('' Crocidura suaveolens'') bones have been found in Roman or early medieval middens; it was last recorded in 1964. There are no recent records.
Breeding birds
The SSSI citation lists five species of breeding birds on the island including the Puffin (''Fratercula arctica
The Atlantic puffin ('), also known as the common puffin, is a species of seabird in the auk family. It is the only puffin native to the Atlantic Ocean; two related species, the tufted puffin and the horned puffin being found in the northeast ...
''). Other breeding seabirds are the Kittiwake ('' Rissa tridactyla''), Herring Gull ('' Larus argentatus''), Lesser Black-backed Gull ('' Larus fuscus'') and a small number of Greater Black-backed Gull ('' Larus marinus''). The seabird breeding colonies are in decline on the Isles of Scilly; in the years 2006–09 the Kittiwake has failed to breed on all the islands bar one chick raised on St Agnes in 2009. Of the species listed above, none have been recorded as breeding on Teän in 2009.
A pair of Marsh Harrier ('' Circus aeruginosus'') bred on Teän in 2008 with two juveniles seen.
Invertebrates
Teän was the site of groundbreaking mark-and-recapture population studies of the Common Blue (''Polyommatus icarus
The common blue butterfly or European common blue (''Polyommatus icarus'') is a butterfly in the family Lycaenidae and subfamily Polyommatinae. The butterfly is found throughout the Palearctic and has been introduced to North America. Butterfli ...
'') butterfly by entomologists
Entomology (from Ancient Greek ἔντομον (''éntomon''), meaning "insect", and -logy from λόγος (''lógos''), meaning "study") is the branch of zoology that focuses on insects. Those who study entomology are known as entomologists. In ...
E. B. Ford and Prof W. H. Dowdeswell, who camped on the island from 26 August to 8 September 1938. They marked each insect with a dot of cellulose paint so that it was possible to tell the date of first capture and any subsequent recaptures. The Common Blue is not a migratory butterfly and no marked butterflies were captured on the west side of St Martin's, so additions to the Teän population were likely to be mainly emergences and losses due to death. It was noted that the normal form of the butterfly was found on St Mary's, Tresco and St Martin's whilst on Teän there is a separate race, due to isolation. Ford's description is below.
The females obtained in the summer (I have no knowledge of the spring form) have an extensive scattering of pale silvery-blue scales, so that they are most unlike those found elsewhere, which are neither blackish or else marked with a violet shade. Moreover, the form from Teän is associated with a characteristic variation on the under-side of the hind-wings, which affects both sexes; for in a large proportion of the specimens the two spots placed along the coastal margin are united, forming a short curved line, and other varieties in spotting are frequent. We seem to here a stage in the evolution of an independent sub-species.
Recent visits have not found the Common Blue to be significantly different on Teän so Ford's remarkable form no longer seems to exist; unusual female colour forms and aberrations may just occur more frequently on Scilly than elsewhere.
Red Barbed Ant (''Formica rufibarbis'')
The Red Barbed Ant has been described as "...perhaps the rarest resident animal in mainland Britain" with only four nests in Surrey
Surrey () is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Greater London to the northeast, Kent to the east, East Sussex, East and West Sussex to the south, and Hampshire and Berkshire to the wes ...
and extinct in Cornwall (last recorded in 1907). It is found on St Martin's, the Eastern Isles and also Teän where it was recorded in 2008. Its favoured habitat is open heathland with plenty of bare ground. Queens
Queens is the largest by area of the Boroughs of New York City, five boroughs of New York City, coextensive with Queens County, in the U.S. state of New York (state), New York. Located near the western end of Long Island, it is bordered by the ...
from St Martin's are captured and taken to Surrey to maintain those colonies.[Spalding, Adrian. (2009) ''Ants'' In CISFBR, ''Red Data Book for Cornwall and the Isles of Scilly'' 2nd Edition. Praze-an-Beeble: Croceago Press.]
References
External links
Lowland heathland - a cultural and endangered landscape
The Isles of Scilly Area of Outstanding Beauty
The Isles of Scilly Wildlife Trust
Geological Conservation Review
*
{{DEFAULTSORT:Tean
Uninhabited islands of the Isles of Scilly
Sites of Special Scientific Interest in the Isles of Scilly
Sites of Special Scientific Interest notified in 1971