The BGS Lexicon of Named Rock Units — Result Details

Ben Bowie Lava Member

Computer Code: BBLA Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: A lower unit, exposed only in the south-west, consists of 15 m of basaltic tuff overlain by a 6 m thick plagioclase-microphyric basalt to hawaiite lava (Jedburgh type). The overlying sequence consists of several flows of plagioclase-macrophyric basalt to hawaiite (Markle type) and two flows of mugearite.
Definition of Lower Boundary: Basal plagioclase-macrophyric basalt to hawaiite lava, or tuff in the south-west, rests upon sandstone and siltstone of the Inverclyde Group.
Definition of Upper Boundary: Top not preserved; removed by erosion.
Thickness: Over 60 m.
Geographical Limits: An outlier measuring 1000 m by 500 m on the summit of Ben Bowie. This could be an attenuated distal part of either the Renfrewshire Hills or the Kilpatrick Hills lava fields. However, the basal pyroclastic unit, the presence of a small plug of plagioclase-macrophyric basalt to hawaiite and the rubbly nature of some of the flows suggest a proximal sequence, extruded from a local volcanic centre.
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Outlier on summit of Ben Bowie, 4 km east of Helensburgh. Paterson et al., 1990. 
Reference(s):
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:
S030