The BGS Lexicon of Named Rock Units — Result Details

Kelso Volcanic Formation

Computer Code: KT Preferred Map Code: notEntered
Status Code: Full
Age range: Courceyan Substage (CF) — Courceyan Substage (CF)
Lithological Description: The Kelso Volcanic Formation comprises effusive alkali olivine-basalts either associated with tuffs or with sedimentary strata (volcaniclastic-sandstone). Up to 12 basalt, basaltic hawaiite and hawaiite lavas are intercalated with thin tuffs and sedimentary rocks. The lower flows are mostly feldspar phyric in contrast to the upper ones which contain olivine and clinopyroxene phenocrysts. The rocks are pervasively altered. The lavas were extruded during the main initial phase of extensional faulting associated with development of the Northumberland Trough.
Definition of Lower Boundary: The olivine basalts of the Kelso Volcanic Formation conformably overlie sandstone of the Kinneswood Formation (Inverclyde Group).
Definition of Upper Boundary: The olivine basalts of the Kelso Volcanic Formation are conformably overlain by "cementstone"-bearing strata comprising interbedded sandstone, siltstone and ferroan dolomite of the Ballagan Formation (Inverclyde Group).
Thickness: About 120m, thinning northwards.
Geographical Limits: The Kelso Volcanic Formation is restricted to Berwickshire and forms a roughly horseshoe-shaped outcrop between the Blackadder Water (380250 650540) near Duns and Carham-on-Tweed (379790 638340), northwest of the Cheviot Massif in the Tweed Basin. It is correlated with the Birrenswark Volcanic Formation of the Solway Basin.
Parent Unit: Inverclyde Group (INV)
Previous Name(s): Kelso Lavas (-4139)
Kelso Traps (-2275)
Alternative Name(s): Birrenswark Volcanic Formation
Stratotypes:
Partial Type Section  Catmoss Quarry, south of Greenlaw exposes the lowest examined lava flow, fresher than many of the outcrops. It is a dark fine-grained sparsely porphyritic olivine basalt of the Jedburgh type. Eckford and Ritchie, 1939. 
Partial Type Section  Partial type sections in the Blackadder Water at Lintmill [NT 7338 4636] and adjacent Lintmill Railway Cutting (GCR Site; see grid references) 3km east of Greenlaw. In the Railway Cutting at least six lava flows with intercalated tuffaceous sandstone strata are identified. The lavas are microporphyritic olivine-basalts of Jedburgh and Dalmeny types and feldspar macroporphyritic olivine basalts of Markle and Dunsapie types. Millward and Williamson. 2003. 130-132 
Reference(s):
George, T N, Johnson, G A L, Mitchell, M, Prentice, J E, Ramsbottam, W H C, Sevastopulo, G D and Wilson, R B. 1976. A correlation of the Dinantian rocks of the British Isles. Special Report of the Geological Society of London, No 7. 
McRobert, R W, 1920. Igneous rocks of Teviot and Liddesdale. Transactions of the Edinburgh Geological Society, Vol.11, 86-103. 
Peach, B N and Horne, J .1903. The Canonbie coalfield: its geological structure and relations to the Carboniferous rocks of the north of England and central Scotland. Transactions of the Royal Society Edinburgh, 40, 835-77. 
Smedley, P L, 1986. Petrochemistry of Dinantian volcanism in northern Britain. Unpublished Ph D thesis, University of Edinburgh. 
Tomkeieff, S I, 1953. The Carboniferous igneous rocks of the Kelso district. Proceedings of the University of Durham Philosophical Society, Vol.11, 95-101. 
Eckford, R J A and Ritchie, M. 1939. The igneous rocks of the Kelso district. Transactions of the Edinburgh Geological Society, Vol.13, 464-472. 
Millward, D and Williamson, I T. 2003. Dinantian volcanic rocks of the Northumberland, Solway and Tweed basins. 109-143, in Stephenson, D, Loughlin, S C, Millward, D, Waters, C N and Williamson, I T. Carboniferous and Permian igneous rock of Great Britain north of the Variscan Front. Geological Conservation Review Series. No.27. (Joint Nature Conservation Committee:Peterborough). 
Greig, D C. 1988. Geology of the Eyemouth district. Memoir of the British Geological Survey, Sheet 34 (Scotland). 
Trewin, N H (editor). 2002. The Geology of Scotland. Geological Society of London: Chapter 9 by Read, Browne, Stephenson and Upton; pp268, 292-293. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S034 S025 S025 S026 E003