Writhlington SSSI () is a 0.5

hectare The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100- metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre i ...

geological 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 Is ...

near the town of

Radstock Radstock is a town and civil parish on the northern slope of the Mendip Hills in Somerset, England, about south-west of Bath and north-west of Frome. It is within the area of the unitary authority of Bath and North East Somerset. The Radsto ...

Bath and North East Somerset Bath and North East Somerset (B&NES) is a unitary authority district in England. Bath and North East Somerset Council was created on 1 April 1996 following the abolition of the county of Avon. It is part of the ceremonial county of Somerset. ...

, notified in 1992. This is the site of old mine workings on the Somerset coalfield, including 3,000 tons of Upper Carboniferous spoil from which more than 1,400 insect fossil specimens have been recovered, including the world's earliest known

Damselfly Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller and have slimmer bodies. Most species fold the wings along ...

. It is a

Geological Conservation Review The Geological Conservation Review (GCR) is produced by the UK's Joint Nature Conservation Committee and is designed to identify those sites of national and international importance needed to show all the key scientific elements of the geological ...

Site, because it has yielded the largest ever collection of

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferou ...

insects in Britain. The commonest forms belong to the order

Blattodea Blattodea is an order of insects that contains cockroaches and termites. Formerly, termites were considered a separate order, Isoptera, but genetic and molecular evidence suggests they evolved from within the cockroach lineage, cladistically mak ...

(cockroaches) and include the extinct families Archimylacris and

Mymarommatidae The Mymarommatidae, sometimes referred to as false fairy wasps. are a very small family of microscopic parasitic wasps. Only about half of the known species are living taxa (the others are fossils), but they are found worldwide.Gibson, G.A.P.; R ...

Protorthoptera The Protorthoptera are an extinct order of Palaeozoic insects, and represent a wastebasket taxon and paraphyletic assemblage of basal neoptera. They appear during the Middle Carboniferous (late Serpukhovian or early Bashkirian), making them among ...

and Palaeodictyoptera also occur. Frequent chelicerates (arthropods) include trace and body fossils of xiphosurid merostomes and arachnids, including

Phalangiotarbi Phalangiotarbi ( Haase, 1890) is an extinct arachnid order first recorded from the Early Devonian of Germany and most widespread in the Upper Carboniferous coal measures of Europe and North America. The last species are known from the early Permia ...

and

Trigonotarbida The order Trigonotarbida is a group of extinct arachnids whose fossil record extends from the late Silurian to the early Permian ( Pridoli to Sakmarian).Dunlop, J. A., Penney, D. & Jekel, D. 2020A summary list of fossil spiders and their relative ...

and also true spiders (Araneida). Rare

myriapods Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. The fossil record of myriapods reaches back into the late Silurian, ...

(millipedes) and occasional

conchostracan Clam shrimp are a group of bivalved branchiopod crustaceans that resemble the unrelated bivalved molluscs. They are extant and also known from the fossil record, from at least the Devonian period and perhaps before. They were originally classifi ...

crustaceans (clam-shrimps) also occur.English Nature citation sheet for the site
(accessed 17 July 2006)

References

{{SSSIs Avon geological Sites of Special Scientific Interest in Avon Radstock Sites of Special Scientific Interest notified in 1992 Somerset coalfield