The BGS Lexicon of Named Rock Units — Result Details

Hopetoun Member

Computer Code: HON Preferred Map Code: HON
Status Code: Full
Age range: Asbian Substage (CR) — Brigantian Substage (CX)
Lithological Description: A sequence of black to grey mudstones, grey siltstones, white, grey and pink sandstones and white to pale-greenish grey calcareous mudstones ("marl") with thin beds of black to grey oil-shales, coals (Hurlet, Two Foot and Houston seams), grey to white, pure to argillaceous limestones and dolostones that comprise the upper part of the West Lothian Oil-Shale Formation. Some lapilli-tuff beds and thin coal seams are present. The strata are not generally disposed in readily recognizable sedimentary cycles and almost all are of lacustrine and fluvial origins. The member includes the Camps, Under Dunnet, Dunnet, Broxburn, Fells, Grey, Mungle, Raeburn and Fraser shales (oil-shales), and the Dunnet and Binny sandstones that were worked in the past for dimension stone. The limited number of thin marine bands include the Dunnet, Raeburn and Fraser Shell Beds (fossiliferous mudstone beds with a marine fauna) and the Under or Gilmerton Bone Bed Limestone. Lacustrine limestones are present, such as the Barracks Limestone with the regionally important and thick Burdiehouse Limestone at the base of the member. The Bathgate Hills Volcanic Formation (Bathgate Group) basaltic lavas and tuffs are interbedded near the top in the West Lothian and Falkirk areas.
Definition of Lower Boundary: Drawn at the base of the Burdiehouse Limestone (Mitchell and Mykura, 1962 p67), resting on strata of the Calders Member. This distinctive limestone is a lacustrine deposit, commonly 6-9m thick, containing abundant fossilised ostracod, plant and fish remains.
Definition of Upper Boundary: The top of this generally non-cyclic unit is defined at the base of the Hurlet Limestone, this marine limestone forming the base of the marine-dominated cyclic successions of the overlying Lower Limestone Formation (Clackmannan Group). The Hurlet Coal is the topmost named bed in the member in West Lothian.
Thickness: Average thickness is approximately 830m in the Lothians (Cameron and McAdam, 1978, Fig.2).
Geographical Limits: West Lothian and part of Midlothian.
Parent Unit: West Lothian Oil-Shale Formation (WLO)
Previous Name(s): Oil Shale Group, Upper (-2246)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Basal part of shore section from Queensferry to Port Edgar. 
Partial Type Section  Shore section at Abercorn, partial section from Raeburn Shale downwards of limited exposure and limited quality. 
Reference Section  Almond river valley at Mid Calder, West Lothian, from the Broxburn Shale downwards. 
Reference Section  Coastal section at Limekilns, in Fife. 
Type Area  Shore section, Abercorn, near Hopetoun, plus numerous boreholes. 
Reference(s):
Chisholm, J I, MacAdam, A D, Brand, P J. 1989. Lithostratigraphical classification of Upper Devonian and Lower Carboniferous rocks in the Lothians. British Geological Survey Technical Report, WA/89/26. 
Mitchell, G H. 1962. The geology of the neighbourhood of Edinburgh. (Explanation of Sheet 32) Third Edition. (Reprinted 1980). Memoir of the Geological Survey of Great Britain (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S024 S031 S032 S032 S040 S040