The BGS Lexicon of Named Rock Units — Result Details

Auch Gleann Psammite Formation

Stratotypes:
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)
Previous Name(s):	Moine [Obsolete Name and Code: Use AUGL] (-3810) Grampian Group (Undivided) (-660)
Alternative Name(s):	none recorded or not applicable
Reference Section	Allt Coralan (Glen Coralan), tributary of Auch Gleann, upstream from railway viaduct. Details will be included in Sheet Description for Sheet 46W (Crianlarich);Presently in draft BGS internal report: Leslie et al. Progress Report on Geology of the Tyndrum area, 2003. 1:50k Sheet 46W (Crianlarich).
Reference(s):
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

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