The BGS Lexicon of Named Rock Units — Result Details

Noddsdale Volcaniclastic Member

Computer Code: NODV Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: Purple basaltic tuffs, agglomerates and pyroclastic breccias with some bedded volcaniclastic sandstones. A complete section through the unit is recorded in the Largs Borehole [NS 2158 5936] with 44 m of volcanic detritus, fine to coarse grained with basaltic lava blocks up to 0.2 m long, bedded in places. Fine grained with accretionary lapilli in basal 3 m. The volcanic detritus is underlain by 11 m of silty mudstone and then 7 m of tuffaceous sandstone containing lava clasts and quartz. Clasts of lava in sandstones and agglomerates are locally derived. Fine-grained tuffs are commonly well bedded and grade into water-laid volcaniclastic and quartzose sandstones containing some carbonised plant debris.
Definition of Lower Boundary: In the area between Loch Thom [NS 26 72] and Largs [NS 20 59], east of the Largs Fault-zone, the basal tuffs, agglomerates and breccias of the Noddsdale Volcaniclastic Member rest upon cornstone-bearing sandstone of the Kinnesswood Formation. Farther north and to the west of the Largs Fault-zone between Outerwards Reservoir [NS 232 654] and Rottenburn Bridge [NS 25 69], the Noddsdale Volcaniclastic Member overlies strata from the Clyde Sandstone Formation.
Definition of Upper Boundary: The tuffs, agglomerates and pyroclastic breccias of the Noddsdale Volcaniclastic Member are overlain by the olivine-microphyric basalt (Dalmeny) lavas of the Largs Lava Member. In the Largs Borehole 107 m of grey feldspar-phyric lava overlie the volcaniclastic sedimentary rocks.
Thickness: 0-200 m
Geographical Limits: Restricted to the western margin of the Renfrewshire Hills, the unit forms the base of the volcanic formation in the area between Loch Thom [NS 26 72] and Largs [NS 20 59]. Does not crop out south of Largs but is inferred beneath Largs Lava Member to the A760 [NS 21 57].
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): Noddsdale Volcaniclastic Beds (-3586)
Alternative Name(s): none recorded or not applicable
Type Section  A complete sequence through the Noddsdale Volcaniclastic Member is seen in the Largs Borehole [NS 2158 5936]. Paterson et al., 1990. A full description of the borehole is available in BGS borehole records. 
Johnstone, G S. 1965. The volcanic rocks of the Misty Law-Knockside Hills district, Renfrewshire. Bulletin of the Geological Survey of Great Britain. No. 22. pp 53-64. 
Richey, J E. 1928. The north Ayrshire sequence of Calciferous Sandstone volcanic rocks. Transactions of the Geological Society of Glasgow. 18. pp 247-255. 
Monro, S K. 1999. Geology of the Irvine District. Memoir of the British Geological Survey, Sheet 22W and part of 21E (Scotland). 
Paterson, I B, Hall, I H S and Stephenson, D. 1990. Geology of the Greenock district: Memoir for 1:50000 geological sheet 30W and part of sheet 29E (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used: