The BGS Lexicon of Named Rock Units — Result Details

St Mellion Formation

Computer Code: SME Preferred Map Code: notEntered
Status Code: Full
Age range: Tournaisian Stage (CT) — Arnsbergian Substage (CG)
Lithological Description: Interbedded dark grey sandstone and mudstone with scattered siltstone beds. Sandstones tend to be concentrated in packets are are medium- to thick- bedded. Rare polymict conglomerate sandstones and argillaceous sandstones are locally present.
Definition of Lower Boundary: Not seen; all observed contacts are tectonic.
Definition of Upper Boundary: Not seen; all observed contacts are tectonic.
Thickness: In excess of 500m, but may be more or less, due to thrusting.
Geographical Limits: St Mellion area (SX 39 65), between Bodmin Moor and Dartmoor, east Cornwall. The area mapped as Crackington Formation on Sheets 338 (Reid et al. 1912; BGS, 1995) and 339 (Selwood et al, 1984) between Holne (SX 715 695) and Haytor Vale (SX 770 770), southeast of Dartmoor may also be St Mellion Formation, but further work is needed.
Parent Unit: Teign Valley Group (TEVY)
Previous Name(s): Crackington Formation (CKF)
Cotehele Formation (-1829)
Middle Culm [Obsolete Name And Code: See SME] (MCU)
Crocadon Formation [Obsolete Name And Code: Use SME] (CDON)
Culm Measures (-3967)
Cotehele Sandstone Formation [Obsolete Name And Code: Use SME] (COTS)
Middle Culm Measures (-719)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Road section (A388) at Paynters Cross, 1.5km southeast of St Mellion, east Cornwall. Section exposes thin- to medium-bedded sandstones and mudstones with several units of massive to thick-bedded sandstones. Three fault slices of Teign Chert Formation occur in the recumbently folded and faulted sequence. Lrveridge et al., 2002. 
Type Area  The St. Mellion outlier, in a largely thrust and fault bounded outcrop on the west of the River Tamar to the north of Pillaton. 
Reference(s):
Waters, C N, Waters, R A, Barclay, W J, and Davies, J R. 2009. Lithostratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/09/01. 184pp. 
Reid, C, Barrow, G, Sherlock, R L, MacAlister, D A and Dewey, H, 1911. The geology of the country around Tavistock and Launceston. Memoir of the Geological Survey of Great Britain, Sheet 337 (England and Wales). 
Whiteley, M J. 1981. The faunas of Viverdon Down area, Southeast Cornwall. Proceedings of the Ussher Society, Vol.5, 186-193. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E337 E338 E348