The BGS Lexicon of Named Rock Units — Result Details

Duddon Conglomerate Member

Computer Code: DUCO Preferred Map Code: Dc
Status Code: Full
Age range: Courceyan Substage (CF) — Courceyan Substage (CF)
Lithological Description: Conglomerate, sandstone and mudstone, mainly red-brown with pale green and mottled layers. Large clasts (pebbles up to 15cm) are well rounded, commonly with thin ferruginous skins. Clast lithologies all occur locally and include Borrowdale Volcanic Group andesite, tuff and rhyolite, Silurian "grit" and "greywacke" and Eskdale Granite and Ennerdale granophyric microgranite.
Definition of Lower Boundary: At base of conglomerate sequence unconformable on the top of the Lower Palaeozoic basement.
Definition of Upper Boundary: There is an upward change from conglomerate beds to grey, red and green marine mudstone and limestone with subordinate thin conglomerate beds. The junction may be sharply gradational or possibly an onlap surface.
Thickness: 0 to 191m
Geographical Limits: Furness, Cumbria confined to the area of the Duddon Estuary.
Parent Unit: Marsett Sandstone Formation (MASA)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Section  Borehole SD27NW/323, between 88.52m and 255.50m. [see definition of Parent formation] Rose and Dunham, 1977. 
Johnson, E W, Soper, N J, Burgess, I C, Ball, D F, Beddoe-Stephens, B, Carruthers, R M, Fortey, N J, Hirons, S, Merritt, J W, Millward, D, Roberts, B, Walker, A B and Young, B. 2001. Geology of the country around Ulverston. Memoir of the British Geological Survey, England and Wales, Sheet 48. 
Rose, W C C. 1977. Geology and Hematite deposits of South Cumbria. Economic Memoir for 1:50,000 Sheet 58 and southern part of Sheet 48. Memoir of the geological Survey of Great Britain. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: