|Site of Special Scientific Interest|
|Area of Search||Somerset|
|Area||1.3 hectares (0.013 km2; 0.0050 sq mi)|
|Natural England website|
Holwell Quarries represent an internationally important geological locality. A comprehensive assemblage of Triassic (including Rhaetic), Lower Jurassic and Middle Jurassic fissure fillings are well displayed. The Rhaetic fissure fillings have yielded the richest assemblage of vertebrate faunas known from the British Triassic. Fissure deposits have also yielded 8 or 9 genera of Reptiles: a Crocodilian, a Placodont (the first record in Britain of this sub-order), and the dinosaurs Thecodontosaurus and Palaeosaurus. The Lower Jurassic fissure fillings yield ammonites and brachiopods which are important in dating these deposits.
- English Nature citation sheet for the site (accessed 10 August 2006)
- English Nature website (SSSI information)