The BGS Lexicon of Named Rock Units — Result Details

Calders Member

Computer Code: CDE Preferred Map Code: CDE
Status Code: Full
Age range: Asbian Substage (CR) — Asbian Substage (CR)
Lithological Description: The Calders Member comprises a succession of black to grey mudstones, grey siltstones and white, grey and pink sandstones with thin beds of grey argillaceous limestones and dolostone (cementstone), and algal-rich black to grey oil-shales with some lapilli-tuff beds. The strata are not disposed in readily recognisable sedimentary cycles, and almost all are of lacustrine and fluvial origins. The member includes the Dalmahoy Oil-Shale, Hailes Sandstone (with a maximum thickness of about 57m that was much worked in the past for dimension stone, and the Pumpherston Oil-Shale. A regionally persistent but thin (<1 m thick) algal dolostone has been recognised at Hopetoun and Queensferry.
Definition of Lower Boundary: The Redhall (Humbie) Marine Band defines the base of the member, the lowest of the Macgregor Marine Bands. This bed is up to 0.3m thick and in Edinburgh is contained within at least 13.8 m of generally tough, black and dark grey mudstones, the lowest 9m of which form the top of the underlying Gullane Formation (Chisholm and Brand, 1994, p.100) and assigned to the currently undefined Wardie Shales Member.
Definition of Upper Boundary: Defined as the base of the Burdiehouse Limestone (Mitchell and Mykura, 1962, p.67). This distinctive limestone, at the base of the overlying Hopetoun Member, is a lacustrine deposit, 6 - 9m thick, containing abundant fossilised ostracod, plant and fish remains and rare algal oncoliths.
Thickness: The average thickness is 290m (Cameron and McAdam, 1978, fig.2), but it is estimated to reach 350m west of Edinburgh.
Geographical Limits: West Lothian; Midlothian (part).
Parent Unit: West Lothian Oil-Shale Formation (WLO)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Section  Shore section at Queensferry between Longcraig Pier and just east of the Forth Railway Bridge [NT 138 784]. (Carruthers et al, 1927, p.80; McAdam and Clarkson, 1986, map 24). 
Reference Section  Shore and coastal section at Hopetoun. 
Reference Section  River section in the Water of Leith near Redhill in Edinburgh (Chisholm and Brand, 1994, p.100). Exposes the Redhall Marine Band and overlying mudstones with oil-shales, up to the base of the Hailes Sandstone. 
Carruthers, R G, Caldwell, W, Bailey, E M and Conacher, H R J. 1927. The oil-shales of the Lothians. Memoir of the Geological Survey of Great Britain. 
Chisholm, J I and Brand, P J. 1994. Revision of the late Dinantian sequence in Edinburgh and West Lothian. Scottish Journal of Geology, Vol.30, 97-104. 
McAdam, A D and Clarkson, E N K. 1996. Lothian Geology: an Excursion Guide. Edinburgh Geological Society, 2nd edition. 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S040 S040 S032 S024 S032