Middridge Quarry is 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 ...

County Durham County Durham, officially simply Durham, is a ceremonial county in North East England.UK General Acts 1997 c. 23Lieutenancies Act 1997 Schedule 1(3). From legislation.gov.uk, retrieved 6 April 2022. The county borders Northumberland and Tyne an ...

, England. It is a disused quarry, situated alongside the railway line between

Newton Aycliffe Newton Aycliffe is a town in County Durham (district), County Durham, England. Founded in 1947 under the New Towns Act 1946, New Towns Act of 1946, the town is to the north of Darlington and to the south of Durham, England, Durham. It is the ...

and

Shildon Shildon is a town and civil parish in County Durham (district), County Durham, in England. The population taken at the 2011 Census was 9,976. The town has the Locomotion Museum, due to it having the first , built in 1825, and locomotive works on ...

, 1 km south of the village of

Middridge Middridge is a village and civil parish in County Durham, England. It is situated east of Shildon and north-west of Newton Aycliffe. The village is situated near a quarry that was mined by the people many generations ago. There is one public h ...

. The quarry was excavated in

Magnesian Limestone The Magnesian Limestone is a suite of carbonate rocks in north-east England dating from the Permian period. The outcrop stretches from Nottingham northwards through Yorkshire and into County Durham where it is exposed along the coast between Ha ...

, the lowest level of which is an exceptionally fossiliferous

marl Marl is an earthy material rich in carbonate minerals, Clay minerals, clays, and silt. When Lithification, hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. M ...

slate Slate is a fine-grained, foliated, homogeneous, metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade, regional metamorphism. It is the finest-grained foliated metamorphic ro ...

which has yielded the richest and most varied Permian flora in the Britain and is the type locality for the

pteridosperm Pteridospermatophyta, also called pteridosperms or seed ferns, are a polyphyletic grouping of extinct Spermatophyte, seed-producing plants. The earliest fossil evidence for plants of this type are the Lyginopteridales, lyginopterids of late Devon ...

''Pseudoctensis middridgensis''. Fossils obtained from the quarry have included several species of fish and reptiles, numerous invertebrates and plants, and the site is considered to be of international palaeontological importance.

References

Sites of Special Scientific Interest in County Durham Quarries in County Durham {{Durham-geo-stub