The BGS Lexicon of Named Rock Units — Result Details

Auch Gleann Psammite Formation

Computer Code: AUGL Preferred Map Code: AUGL
Status Code: Full
Age range: Cryogenian Period (AC) — Cryogenian Period (AC)
Lithological Description: Interbedded pink quartzofeldspathic psammite and grey micaceous grey psammite. Parallel bedded psammite layers 10-20cm thick develop plane parallel internal lamination defined by alternations of more micaceous and quartzofeldspathic layers at a mm scale. Similar scale but undulose bedded forms also present with rare preservation of hummocky cross stratification. Subsidiary 50-100cm-thick massive beds may have a lenticular form and may be indicative of channel or sand-wave macroforms. Semipelite to pelite comprises a very minor part of the Formation but forms in layers up to 15m thick.
Definition of Lower Boundary: Not seen.
Definition of Upper Boundary: Abrupt change to white weathering pinkish-brown quartzose psammite and quartzite of the succeeding Beinn a' Chaisteil Formation.
Thickness: >1000m.
Geographical Limits: Includes all of the Grampian Group psammite rocks which extend across the northern parts of 1:50k sheets 46W (Crianlarich) and 46E (Killin).
Parent Unit: Glen Spean Subgroup (GRGS)
Alternative Name(s): none recorded or not applicable
Reference Section  Allt Coralan (Glen Coralan), tributary of Auch Gleann, upstream from railway viaduct. 
In preparation. BGS Sheet Description for Sheet 46W (Crianlarich) and 46E (Killin). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable