Townburn Sandstone Member

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Townburn Sandstone Member (TWN), Carboniferous, Midland Valley of Scotland[edit]

Townburn Sandstone Member is part of the Passage Formation


The Townburn Sandstone Member derives its name from its reference section (see Stratotype below). Previous names include the Crichope Sandstone Member and Passage Group (undivided).[edit]


Mainly medium- to coarse-grained sandstone with subsidiary conglomerate and pebbly sandstone.

Genetic interpretation[edit]

The member comprises fluvial-channel sands deposited in low sinuousity braided channels. (McMillan, 2002, p..74[1]; Jones, 1994[2]).


The type section is between 161.39 and 202.94 m depth in the Crichope Linn Borehole (BGS Registration Number NX99NW/1) (NX 9093 9551). A reference section is the Town Burn, Townburn Wood, Closeburn, 650 m north-east of Barraby Farm (NX 9146 9390). McMillan (2002, p. 71)[1] described this exposure as one of several localities in the Thornhill district where sequences up to 15 m thick of pebbly sandstone and beds of conglomerate can be seen (see also Simpson and Richey, 1936[3]).

Lower and upper boundaries[edit]

The lower boundary is unconformable on the mainly sandstone turbidites of the Lower Palaeozoic Glenlee Formation (Ordovician) and Gala Group (Silurian), though it rests locally on the Lower Carboniferous limestone and dolomitic limestone with interbedded sandstone, siltstone and mudstone of the Closeburn Limestone Formation, or the mudstone and siltstone with interbedded sandstone of the Enterkin Mudstone Formation.

The base of the nonmarine fossiliferous Scottish Lower Coal Measures Formation conformably overlies the fossil-free Townburn Sandstone Member.


Some 41.55 m in the Crichhope Linn Borehole (see above).

Distribution and regional correlation[edit]

Thornhill Basin at Closeburn, Keir, Eccles, River Nith (Drumlanrig), Hapland, Fellend, Townhead and Morton Wood.


Namurian to Westphalian.


  1. 1.0 1.1 McMillan, A A.2002.Geology of the New Galloway and Thornhill district.Memoir of the British Geological Survey, Sheets 9E and 9W (Scotland).
  2. Jones, N S.1994.Core log of the BGS Closeburn Borehole [NX 90210 91450].British Geological Survey Technical Report, WH/94/147R.
  3. Simpson, J B, and Richey, J E.1936.The geology of the Sanquhar coalfield and adjacent basin of Thornhill.Memoir of the Geological Survey of Great Britain, Sheets part 9 and 15 (Scotland).