Hopetoun Member is part of the West Lothian Oil-Shale Formation
The name was proposed by Chisholm et al. (1989) to replace the Upper Oil Shale Group of Carruthers et al. (1927) and Mitchell and Mykura (1962). It originates from the best natural sections, which are on the coast near Hopetoun House.
The Hopetoun Member consists of a sequence of black to grey mudstone, grey siltstone, white, grey and pink sandstone and white to pale greenish grey calcareous mudstone with thin beds of black to grey oil shale, coals (Hurlet, Two Foot and Houston seams); together with grey to white, pure to argillaceous limestone and dolostone that comprise the upper part of the West Lothian Oil-Shale Formation. Some lapilli-tuff beds are present and thin coal seams. The strata are not generally disposed in readily recognisable sedimentary cycles. 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 beds 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. The Hurlet Coal is the topmost named bed in the member in West Lothian.
The strata are almost all of lacustrine and fluvial origins with a limited number of marine incursions.
The shore at Abercorn (NT 061 794 to 088 793) provides a partial type section of limited exposure and modest quality. It includes from the Raeburn Shale downwards. Reference sections occur on the shore at Queensferry (NT 127 784) to Port Edgar (NT 138 784) (basal part of the member) and in the River Almond valley at Mid Calder, West Lothian (NT 079 671 to 086 685) (from the Broxburn Shale downwards).
Lower and upper boundaries
The lower boundary is defined at the base of the Burdiehouse Limestone (BULS) (Mitchell and Mykura, 1962, p..67) (Figure 6, Column 4D) resting on strata of the Calders Member. This distinctive limestone is a lacustrine deposit, commonly 6–9 m thick, containing abundant fossilised ostracod, plant and fish remains, and rarely algal oncoids.
The top of the generally noncyclic Hopetoun Member is defined at the base of the Hurlet Limestone (Figure 6, Column 4D). This marine limestone forms the base of the marine-dominated cyclic successions of the overlying Lower Limestone Formation (Clackmannan Group).
The member is on average about 830 m thick in the Lothians (Cameron and McAdam, 1978, fig. 2).
Distribution and regional correlation
West Lothian and part of Midlothian.
Asbian to Brigantian
- Chisholm, J I, McAdam, A D, and Brand, P J.1989.Litho-stratigraphical classification of Upper Devonian and Lower Carboniferous rocks in the Lothians.British Geological Survey Technical Report, WA/89/26.
- Carruthers, R G, Caldwell, W, Bailey, E M, and Conacher, H R J.1927.The oil shales of the Lothians (3rd edition).Memoir of the Geological Survey of Great Britain
- Mitchell, G H, and Mykura, W.1962.The Geology of the neighbourhood of Edinburgh.Memoir of the Geological Survey of Great Britain, Sheet 32 (Scotland)
- Cameron, I B, and McAdam, A D.1978.The oil shales of the Lothians, Scotland: present resources and former workings.Report of the Geological Survey of Great Britain, No. 78/28.