| Ballagan Formation | |
|---|---|
| Stratigraphic range: Tournaisian–Visean | |
 Exposure of alternating siltstone and dolomite layers of the Ballagan Formation in the bank of Tarras Water | |
| Type | Formation |
| Unit of | Inverclyde Group |
| Underlies | Clyde Sandstone Formation |
| Overlies | Kinnesswood Formation |
| Area | Central Lowlands, Northern England |
| Thickness | ~900 m |
| Lithology | |
| Primary | mudstone, cementstone, siltstone |
| Other | sandstone |
| Location | |
| Region | Scotland |
| Country | United Kingdom |
| Type section | |
| Named for | Ballagan Glen |
| Named by | Browne, 1980 |
The Ballagan Formation is a geologic formation in Scotland and England. It preserves fossils dating back to the early part of the Carboniferous period (Tournaisian – early Visean).[1] Its name comes from the "Ballagan Beds" of Ballagan Glen, near Strathblane, which has a good example of this geological formation.[2]
The Ballagan Formation was historically known as the Cementstone Group,[3][4] but more recently it has been placed as the middle formation of the Inverclyde Group.[5] This change was motivated by the recognition that the youngest parts of the Devonian Upper Old Red Sandstone (now known as the Kinnesswood Formation) were geologically continuous with the lowest parts of the Lower Carboniferous Calciferous Sandstone Measures (now known as the Ballagan and Clyde Sandstone formations). This interval of Devonian-Carboniferous overlap was named the Inverclyde Group, and the cementstone-rich "drab beds" in the middle of the group were renamed to the Ballagan Formation.[6] In Lothian, the Ballagan and Clyde Sandstone formations are sometimes known as the Tyninghame Formation.[7]
- ^ British Geological Survey. "Ballagan Formation". BGS Lexicon of Named Rock Units. Retrieved 8 March 2018.
- ^ MacDonald, Hugh (1910). Rambles Round Glasgow (New ed.). Glasgow: John Smith. p. 382.
- ^ Belt, Edward S.; Freshney, Edward C.; Read, William A. (1967). "Sedimentology of Carboniferous Cementstone Facies, British Isles and Eastern Canada". The Journal of Geology. 75 (6): 711–721. doi:10.1086/627295. ISSN 0022-1376. S2CID 140699667.
- ^ Scott, W. B. (1986). "Nodular carbonates in the Lower Carboniferous, Cementstone Group of the Tweed Embayment, Berwickshire: evidence for a former sulphate evaporite facies". Scottish Journal of Geology. 22 (3): 325–345. doi:10.1144/sjg22030325. ISSN 0036-9276. S2CID 129888604.
- ^ Smithson, Timothy R.; Wood, Stanley P.; Marshall, John E. A.; Clack, Jennifer A. (20 March 2012). "Earliest Carboniferous tetrapod and arthropod faunas from Scotland populate Romer's Gap". Proceedings of the National Academy of Sciences. 109 (12): 4532–4537. Bibcode:2012PNAS..109.4532S. doi:10.1073/pnas.1117332109. ISSN 0027-8424. PMC 3311392. PMID 22393016.
- ^ Brown, M.A.E. (1980). "The Upper Devonian and Lower Carboniferous (Dinantian) of the Firth of Tay, Scotland". Report of the Institute of Geological Sciences. 80 (9): 1–13.
- ^ Andrews, Julian A.; Ghulam, Nabi (1994). "Lithostratigraphy of the Dinantian Inverclyde and Strathclyde Groups, Cockburnspath Outlier, East Lothian – North Berwickshire". Scottish Journal of Geology. 30 (2): 105–119. doi:10.1144/sjg30020105. S2CID 129170097.