Kirkbean Cementstone Member
Kirkbean Cementstone Member is part of the Ballagan Formation
The Kirkbean Cementstone Member comprises mainly thinly interbedded greenish grey carbonaceous siltstone and argillaceous limestone (‘cementstone’). In the Langholm and Annandale districts, it includes the Whita and Annandale Sandstone beds respectively. The former comprise medium- to thickly bedded, fine- to coarse-grained, white, grey and pink sandstones with a few thin siltstones and sandy ‘cementstones’, and the latter comprise dark red, fine- to coarse-grained sandstone and locally derived conglomerate.
The partial type section is Kirkbean Glen (NX 9745 5914) where fragmentary plant remains, but no shelly fauna, have been found in a 20 m sequence of carbonaceous siltstones and mudstones with thin ‘cementstone’ stringers, that is faulted against basalt (Lintern and Floyd, 2000, p. 77).
Lower and upper boundaries
The base rests unconformably on basalt lavas of the Birrenswark Volcanic Formation (Figure 10, Column 2).
The top of the member is not exposed, but is probably gradational with the Southerness Limestone Member.
The ‘cementstone’ facies is greater than 100.m thick. The Whita Sandstone in the Langholm district is about 300.m thick (Lumsden et al., 1967, p..78), and the Annandale Sandstone Beds in the Dalton area of Dumfriesshire are 180 m thick.
Distribution and regional correlation
Kirkbean area, Southerness, Kirkcudbrightshire, Dumfries and Galloway.
Tournaisian (Courceyan to Chadian).
- Craig, G Y, and Nairn, A E M.1956.The Lower Carboniferous outliers of the Colvend and Rerrick shores, Kirkcudbrightshire.Geological Magazine, Vol. 93, 249–256
- Lintern, B C, and Floyd, J D.2000.Geology of the Kirkcudbright–Dalbeattie district.Memoir of the British Geological Survey, Sheets 5W and 5E, part 6W (Scotland)
- Lumsden, G I, and Wilson, R B.1961.The stratigraphy of the Archerbeck Borehole, Canonbie, Dumfriesshire.Bulletin of the Geological Survey of Great Britain, No. 18, 1–89