The BGS Lexicon of Named Rock Units — Result Details

Hudleston Formation

Computer Code: HDST Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Bajocian Age (JB) — Bathonian Age (JN)
Lithological Description: The formation is dominantly composed of mudstones, with interbedded siltstone and sandstone beds. Mudstones are variegated, grey-green, purple, red or yellow-brown and poorly calcareous to non-calcareous. Sandstones are poorly cemented, fine- to coarse-grained and grey-brown. Carbonaceous material is common in some beds.
Definition of Lower Boundary: The base of the formation is marked by a downward change from dominantly mudstones to dominantly sandstones (Strangways Formation). The boundary coincides with a sharp down-section decrease in gamma-ray values and increase in velocity.
Definition of Upper Boundary: The upper boundary is usually characterised by a downward change from limestone (at the base of the Leckenby Formation, equivalent to the Cornbrash onshore) to mudstone dominated sediments. It usually coincides with the base of a low gamma/high velocity spike. Below the spike the wireline logs show consistently high gamma values and low velocity, characteristic of the Hudleston Formation. Locally, where the limestone is absent, the upper boundary is placed at a downward change from sandstone to variegated mudstone.
Thickness: none recorded or not applicable
Geographical Limits: Southern North Sea Basin, quadrants 41-43, 46-48, and 51-52.
Parent Unit: West Sole Group (WSTS)
Previous Name(s): West Sole Group (WSTS)
Alternative Name(s): Scalby Formation
Stratotypes:
Type Section  North Sea Well 47/3b-4 between 930 and 979 m (Lott and Knox, 1994). 
Reference Section  North Sea Well 42/24-1 between 249 and 328 m (Lott and Knox, 1994). 
Reference Section  North Sea Well 47/10-1 between 1503 and 1538.5 m (Lott and Knox, 1994). 
Reference Section  North Sea Well 48/3-3 between 895 and 995 m (Lott and Knox, 1994). 
Reference(s):
Lott, G K and Knox, R W O'B. 1994. 7. Post-Triassic of the Southern North Sea. In: Knox, R W O'B and Cordey, W G (eds.) Lithostratigraphic nomenclature of the UK North Sea. [British Geological Survey, Nottingham]. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable