The BGS Lexicon of Named Rock Units — Result Details

Luccombe Breccia Formation

Computer Code: LUBR Preferred Map Code: LuBr
Status Code: Full
Age range: Triassic Period (T) — Triassic Period (T)
Lithological Description: Breccia, sandy breccia, pebbly sandstone and sandstone, reddish brown, commonly calcareous; calcite-veined in places, and locally well-cemented-clasts in breccias; mainly angular platy slate, shale, sandstone and quartz. Thin unit of conglomerate with rounded boulders of Devonian sandstone. Near base, reddish brown, weakly cemented, silty, fine- to medium-grained sandstone unit, up to 70m.
Definition of Lower Boundary: Unconformable: rests on Hangman Sandstone (Eifelian).
Definition of Upper Boundary: Probably unconformable: overlain with probable angular discordance by Mercia Mudstone Group (Triassic).
Thickness: Up to 650 m. estimated.
Geographical Limits: Porlock Basin, west Somerset. Sheet 278 (Minehead).
Parent Unit: Not Applicable (-)
Previous Name(s): Luccombe Breccia Series (-1671)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Village of Luccombe (SS 911 445), west Somerset. No suitable type section. Small quarries between Luccombe and Tivington. 
Type Area  Village of Luccombe. 
Type Area  Village of Luccombe. 
Type Area  Village of Luccombe. 
Type Area  Village of Luccombe. 
Reference Section  Basal sandstone in stream section. 
Reference Section  Conglomerate in lane section in Huish Ball Steep. 
Reference(s):
Thomas, A N. 1940. The Triassic Rocks of North-west Somerset. Proceedings of the Geologists' Association, Vol.51, 1-43. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable