The BGS Lexicon of Named Rock Units — Result Details
Hillhead Sandstone Formation
| Computer Code: | HSA | Preferred Map Code: | Has |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Eifelian Age (DI) — Eifelian Age (DI) | ||
| Lithological Description: | A red and grey, planar-bedded, quartzose, sandstone with interbeds of micaceous siltstone and silty mudstone. | ||
| Definition of Lower Boundary: | Conformable on the Ishes Flagstone Formation. At its type site, the base is taken as a gradual facies change from grey calcareous, laminated fine-grained flaggy sandstone of the Ishes Flagstone, to a red coarser-grained sandstone. | ||
| Definition of Upper Boundary: | Overlain unconformably by red flaggy sandstone of the Nairn Sandstone Formation. | ||
| Thickness: | Up to 920 m thick. | ||
| Geographical Limits: | Sheet S84W (Fortrose). | ||
| Parent Unit: | Inverness Sandstone Group (INS) | ||
| Previous Name(s): | Hillhead Red Bed Subgroup [Obsolete Name And Code: Use HSA]
(HRB)
Hillhead Group (-966) Hillhead Sandstones, Flagstones and Shales [Obsolete Name and Code: Use HSA] (-4101) |
||
| Alternative Name(s): | none recorded or not applicable | ||
| Stratotypes: | |||
| Partial Type Section | Hillhead Quarry, about 100 m south of Hillhead Farm, about 6 km northeast of Smithton, showing only a small proportion of the middle part of the unit, of which some 4 m are exposed. | ||
| Partial Type Section | Leys-Culduthel Quarry on the soutwest side of General Wade's Military Road, about 0.7 km southwest of the outskirts of Inverness. Shows the basal part of the unit only. | ||
| Reference(s): | |||
| Mykura, W. 1991. Old Red Sandstone. 297-346 in Geology of Scotland (3rd edition, revised). Craig, G Y (editor). Geological Society of London. | |||
| Fletcher, T P et al. 1996. Geology of the Fortrose and eastern Inverness district. Memoir of the British Geological Survey, Sheet 84W (Scotland). | |||
| Horne, J, 1923. The geology of the Lower Findhorn and Lower Strath Nairn. Mmemoir of the Geological Survey of Scotland Sheet 84 and prt of 94. | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| S084 | |||