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 44m of volcanic detritus, fine to coarse grained with basaltic lava blocks up to 0.2m long, bedded in places. Fine grained with accretionary lapilli in basal 3m. The volcanic detritus is underlain by 11m of silty mudstone and then 7m 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 107m of grey feldspar-phyric lava overlie the volcaniclastic sedimentary rocks.
Thickness: 0-200m
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. 
Paterson, I B, Hall, I H S & Stephenson, D. 1990. Geology of the Greenock district: Memoir for 1:50000 geological sheet 30W and part of sheet 29E (Scotland). 
Monro, S K. 1999. Geology of the Irvine District. Memoir of the British Geological Survey, Sheet 22W and part of 21E (Scotland). 
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. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: