The BGS Lexicon of Named Rock Units — Result Details

Hyner Shale Formation [Obsolete Name And Code: Use HYMU]

Computer Code: HYSH Preferred Map Code: HySh
Status Code: Index Level
Age range: Famennian Age (DA) — Courceyan Substage (CF)
Lithological Description: Hard dark-blue or bluish-green, generally mottled, shales and mudstones. Calcareous bands and nodules, and calcareous shales and mudstones occur near the top and a calcareous siltstone (yielding rich Famennian faunas locally) forms a small ridge at Hyner (SX 8404 8214) and east of Christow (SX 8407 8488). Where the Hyner Shale is within the metamorphic aureole of the Dartmoor Granite, calc-flintas are common and siliceous nodules are characteristic of the lower parts of the formation..
Definition of Lower Boundary: Not seen.
Definition of Upper Boundary: Passes conformably upwards into grey and green micaceous shales of the Trusham Shale. (Entomozoid ostracods in the upper part of the Hyner Shale define the Devonian-Carboniferous boundary.) In most locations the transition is marked in the field by variation from dark blue or bluish-green mottled shales and calcareous beds at the top of the Hyner Shale (described under Lithology) to grey micaceous and green shales of the Trusham Shale. This boundary cannot be detected in the area between the Lustleigh and Bovey Tracey faults, where the influence of the metamorphic aureole is more prevalent. In this area the Hyner and Trusham shales have not been separated.
Thickness: Uncertain; at least 244m in Teign Valley (Selwood and others, 1984, p.50).
Geographical Limits: Middle Teign Valley area, near Newton Abbot, Devon.
Parent Unit: Not Available (!)
Previous Name(s): Hyner Shale (-4719)
Hyner Formation (-3484)
Alternative Name(s): none recorded or not applicable
Type Section  Named from Hyner (SX 839 820). Road section near Christow, Devon (SX 839 820). Selwood and others, 1984, p.51. 
Selwood, E B, Edwards, R A, Simpson, S, Chesher, J A, Hamblin, R J O, Henson, M R, Riddolls, B W and Waters, R A. 1984. Geology of the countryside around Newton Abbot. Memoir of the British Geological Survey, Sheet 339 (England and Wales). 
Chesher, J A, 1968. The succession and structure of the Middle Teign Valley. Proceedings of the Ussher Society, Vol.2, 15-17. 
Ussher, W A E, 1913. Geology of the country around Newton Abbot. Memoir of the British Geological Survey, Sheet 339. (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used: