Touch House Lava Member

From Earthwise
Jump to navigation Jump to search

Touch House Lava Member (THLA), Fintry-Touch Block, Carboniferous, Midland Valley of Scotland[edit]

Touch House Lava Member is part of the Clyde Plateau Volcanic Formation.

Name[edit]

Previously named the Touch House Group (see Francis et al., 1970[1]).

Lithology[edit]

The Touch House Lava Member consists only of plagioclase-macrophyric basalt or trachybasalt lavas (basalt to hawaiite of ‘Markle’ type) and only the lowest part of the member is well exposed, near the edge of the low-lying fertile land between Touch Home Farm (NS 7518 9331) and Touch House (NS 7535 9276).

Stratotype[edit]

The type area is in the eastern Touch Hills, north-east of Glasgow (NS 7520 9277 to NS 7524 9340) (Francis et al., 1970)[1]. A reference section in the lowest part of the member is provided by exposures between Touch Saw Mill and Touch House, eastern Touch Hills, north-east of Glasgow (NS 7518 9331 to NS 7535 9276).

Lower and upper boundaries[edit]

The basal plagioclase-macrophyric basalt lava of the member is apparently conformable, or disconformable, on the underlying plagioclase-microphyric basalt of the Black Mount Lava Member. The top of the member is not exposed.

Thickness[edit]

Uncertain. The thickness of the member is difficult to estimate because of drift cover, and the lack of knowledge about its upper part (Francis et al., 1970)[1].

Distribution and regional correlation[edit]

The member is restricted to the north-eastern part of the Fintry–Touch Block (Francis et al., 1970)[1] and specifically to a small area in the eastern Touch Hills, north-east of Glasgow. These rocks crop out in an outlier that extends northward from Touch House (NS 7535 9276) to near Touch Home Farm (NS 7524 9340) and westwards to north of Mill Linn (NS 9495 9302).

Age[edit]

Mid Visean (Arundian to Asbian).

References[edit]

  1. 1.0 1.1 1.2 1.3 Francis, E H, Forsyth, I H, Read, W A, and Armstrong, M. 1970. The geology of the Stirling district. Memoir of the Geological Survey of Great Britain, Sheet 39 (Scotland)