The BGS Lexicon of Named Rock Units — Result Details

Horrisdale Waterfalls Member

Computer Code: TCD2 Preferred Map Code: notEntered
Status Code: Full
Age range: Tonian Period (AT) — Tonian Period (AT)
Lithological Description: Siltstone-mudstone, finely interbedded, grey, shaley; grey sandstone with ripple laminations. Coarsening upwards.
Definition of Lower Boundary: Conformably upon Slattadale Member (TCD1).
Definition of Upper Boundary: Sharp contact with overlying Allt na Beiste Member (ALBE) - the lower Member of the Applecross Formation (TCA). Marked by abrupt appearance of trough cross-bedded sandstone.
Thickness: 115 m in type section.
Geographical Limits: Northwest Highlands, from Diabaig to Gairloch.
Parent Unit: Diabaig Formation (TCD)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Stewart, A D. 2002. The later Proterozoic Torridonian rocks of Scotland: their sedimentology, geochemistry and origin. Geological Society Memoir. Vol. 24. (The Geological Society.) 
Krabbendam, M. 2021. A stratigraphic framework for the early Neoproterozoic successions of the Northern Highlands of Scotland. UK Stratigraphic Framework Series. British Geological Survey Open Report, OR/21/072. 86pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S091