The BGS Lexicon of Named Rock Units — Result Details
Bighouse Formation
| Computer Code: | BIGH | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Eifelian Age (DI) — Eifelian Age (DI) | ||
| Lithological Description: | Sequence dominated by thickly bedded aeolian and fluviatile cross-bedded sandstone units with minor interbeds of conglomerate in the lower parts of the sequence, siltstones and microsparitic limestone interbeds also present. Thick mappable sandstone [Fresgoe Sandstone Member] present [topmost unit] also recognisable in borehole core and seismic records. Prominent laminated limestones [Baligill Limestone Member] present in the middle part of the Formation. Breccio conglomerate [Portskerra Conglomerate Member] present locally as basal unit of the formation; bed or beds of limestone [Arylevie Limestone Bed] present within or at the base of the Portskerra Conglomererate Member at some localities. | ||
| Definition of Lower Boundary: | Unconformable contact on Lower Devonian sandstone [Luachair Sandstone Member] and conglomerate [Tobaireach Conglomerate Member] of the Ousdale Arkose Formation. Also unconformable on Caledonian intrusive igneous rocks and Moinian metamorphic basement rocks. | ||
| Definition of Upper Boundary: | Top of Fresgoe Sandstone Member, overlain by Sandside Bay Formation. | ||
| Thickness: | 200 to 250m | ||
| Geographical Limits: | Onshore and immediately offshore of Dounreay area, Caithness, Northern Scotland. | ||
| Parent Unit: | Caithness Flagstone Group (CNFL) | ||
| Previous Name(s): | Bighouse Sandstone Formation [Obsolete Name And Code: See BIGH]
(BIG)
Bighouse Sandstone Formation and lower part of Sandside Sandstone Formation [Obsolete Name and Code: Use BIGH] (-3852) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Partial Type Section | Sandstone dominated sequence on the eastern side of Melvich Bay, extending from c. 200 m northeast of Bighouse to headland c. 400 m northeast of Rubha an Tuir, Southerland. Base of formation not seen. | ||
| Reference Section | Base of Formation only; Portskerra Harbour, c. 500 m north of the centre of Portskerra village Sutherland (Trewin, 1993). See also type sections of Portskerra Conglomerate Member and Fresgoe Sandstone Member. | ||
| Reference(s): | |||
| British Geological Survey. (In preparation, to be published in 2005). Bedrock geology. Scotland Special Sheet (Dounreay). 1:25 000. | |||
| Trewin, N H. 1993 Old Red Sandstone basin margin deposits at Red Point, Port Skerra and Baligill. 157-166 in Trewin, N H and Hurst, A [editors], Excursion guide to the geology of eastern Sutherland and Caithness. [Edinburgh: Scottish Academic Press.] | |||
| Fletcher, T P and Key, R M. 1991. Solid geology of the Dounreay District. British Geological Survey Technical Report WA/91/35C. | |||
| Donovan, R N. 1975. Devonian lacustrine limestones at the margin of the Orcadian Basin, Scotland. Journal of the Geological Society of London, Vol.131, 489-510. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| S115 | |||