Birgidale Formation

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Birgidale Formation (BID), West Central Scotland (Arran, Bute and Cowal, and Glasgow), Carboniferous, Midland Valley of Scotland[edit]

Birgidale Formation is part of the Strathclyde Group.

(Figure 6, Columns 1, 3 and 4A)


From Birgidale Knock Farm, South Bute, Strathclyde Region (Paterson and Hall, 1986)[1].


The Birgidale Formation consists of cyclically deposited grey mudstone, quartz pebble-bearing sandstone and seatearth with coal seams.

Genetic interpretation[edit]

The depositional environment was fluviodeltaic, mainly river channel and floodplains.


The type section is from 32.8 to 54.1 m depth in the Birgidale Knock Borehole (BGS Registration Number NS05NE/2) (NS 0725 5990), the type area being around Birgidale Knock about (NS 074 599) in south Bute.

Lower and upper boundaries[edit]

The base of the formation is sharp, probably erosional, on the Ascog Member of the Clyde Sandstone Formation (Figure 6, Column 3).

The top is overlain by lava, tuff and volcaniclastic sedimentary rocks of the Clyde Plateau Volcanic Formation.


About 16 m (Paterson and Hall, 1986, p. 13)[1]. However, BGS (2008)[2]

Distribution and regional correlation[edit]

Isle of Bute.




  1. 1.0 1.1 Paterson, I B, and Hall, I H S. 1986. Lithostratigraphy of the late Devonian and early Carboniferous rocks in the Midland Valley of Scotland. Report of the British Geological Survey, Vol. 8, No. 3
  2. British Geological Survey. 2008. Dunoon and Millport. Scotland Sheet 29E with part of 21E. Bedrock and Superficial Deposits. 1:50.000. (Keyworth, Nottingham: British Geological Survey.)