The BGS Lexicon of Named Rock Units — Result Details

Hodderense Limestone Formation

Computer Code: BOH Preferred Map Code: BOH
Status Code: Full
Age range: Holkerian Substage (CQ) — Holkerian Substage (CQ)
Lithological Description: Pale olive and blue-grey, to cream-coloured porcellanous wackestones with characteristic dark blue, micritic nodules, sporadic interbedded packstones and common mudstones. Chert is common in the Isle of Man sections and some beds are multi-storey, displaying lag horizons composed of reworked micrite nodules, inadunate crinoids, bellerophontid gastropods, cephalopods, trilobites and sponges. Also present is the trace fossil Helminthoides.
Definition of Lower Boundary: In the Craven Basin the lower boundary is drawn at the base of the first cream-coloured wackestone with dark blue micritic nodules of the Hodderense Limestone Formation, where it rests conformably on grey or dark grey mudstone and calcisiltite of the Hodder Mudstone Formation. In the south Isle of Man, the base of the formation is poorly defined. Where it occurs in the field close [SC 2580 6620] to the Visitor Centre at Scarlett, south of the old lime kilns, the wackestones and packstones of the underlying Knockrushen Formation are overlain by the massive lime mudstones of the Hodderense Limestone Formation. The base of the latter "is taken at the lowest mottled horizon" (Dickson et al., 1987), and this mottling is a result of the presence of blue or grey micrite nodules up to 3cm in size.
Definition of Upper Boundary: In the Craven Basin the upper boundary is drawn at the conformable upward passage from the highest nodule-bearing cream-coloured wackestone bed of the Hodderense Limestone Formation, to the first grey mudstone of the Pendleside Limestone Formation. In the south of the Isle of Man, at Scarlett Point [SC 2583 6633] the upper boundary of the Hodderense Limestone Formation occurs below the lowest black claystone of the wackestones, lime-mudstones and interbedded claystones of the Scarlett Point Member, Bowland Shale Formation.
Thickness: Up to 15m thick in the Craven Basin and 14m in the south of the Isle of Man.
Geographical Limits: Craven Basin, northwest England, although removed beneath the unconformity in the Skipton area; also present in the south of the Isle of Man.
Parent Unit: Craven Group (CRAV)
Previous Name(s): Beyrichoceras Hodderense Bed (-2006)
Bollandoceras Hodderense Beds (-716)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  South of the old lime kilns, near the Visitor Centre at Scarlett, Isle of Man; section shows the base of the formation above the Knockrushen Formation. 
Reference Section  At Scarlett Point, Isle of Man, cliff section shows upper boundary of the Hodderense Limestone Formation, which occurs below the Scarlett Point Member, Bowland Shale Formation. 
Type Section  East bank of the River Hodder, Great Falls, near Stonyhurst, near Clitheroe, Lancashire. 
Reference(s):
Dickson, J A D, Ford, T D and Swift, A. 1987. The stratigraphy of the Carboniferous rocks around Castletown, Isle of Man. Proceedings of the Yorkshire Geological Society, Vol.46, 203-229. 
Riley N J. 1990. Stratigraphy of the Worston Shale Group (Dinantian) Craven Basin, north-west England. Proceedings of the Yorkshire Geological Society, Vol. 48, 163-187. 
Parkinson, D, 1926. The faunal succession in the Carboniferous Limestone and Bowland Shales at Clitheroe and Pendle Hill, Lancashire. Quarterly Journal of the Geological Society of London. Volume 82. p.188-249. 
Wadge, A J et al. 1983. Mineral reconnaissance surveys in the Craven Basin. Institute of Geological Sciences Mineral Reconnaissance Programme Report, Vol.66. 
Chadwick, R A, Jackson, D I, Barnes, R P, Kimbell, G S, Johnson, H, Chiverell, R C, Thomas, G S P, Jones, N S, Riley, N J, Pickett, E A, Young, B, Holliday, D W, Ball, D F, Molyneux, S G, Long, D, Power, G M and Roberts, D H. 2001. Geology of the Isle of Man and its offshore area. British Geological Survey Research Report, RR/01/06. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E059 E067 E068