The BGS Lexicon of Named Rock Units — Result Details

Ardersier Silts Formation

Computer Code: ARDS Preferred Map Code: ARS
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Rhythmically-bedded sequence of silty clays, silts and silty sands, typically graded. Subordinate diamicton and gravel. Origin thought to be glaciomarine.
Definition of Lower Boundary: Unseen; on lodgement till or bedrock.
Definition of Upper Boundary: Gradational contact with Alturlie Gravels Formation above, or unconformable boundary with younger deposits.
Thickness: At least 20m
Geographical Limits: Southern shores of the inner Moray Firth, between Inverness and Elgin.
Parent Unit: Banffshire Coast and Caithness Glacigenic Subgroup (BCD)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  "Kirkton Pit". Old clay pit (re-excavated Sept 1990) in Main Lateglacial Cliffline (trimmed in Mid-Holocene times). 
Partial Type Section  "Contorted silts of Ardersier". Cliff section in Main Lateglacial Cliffline (trimmed in Mid-Holocene times). See Firth, 1989. 
Reference(s):
Firth, C R. 1989. A reappraisal of the supposed Ardersier Readvance, inner Moray Firth. Scottish Journal of Geology, Vol 25, 249-261. 
Fletcher, T P et al. 1996. Geology of the Fortrose and eastern Inverness district. Memoir of the British Geological Survey, Sheet 84W (Scotland). 
Merrit, J W, Auton, C A, and Firth. C R. 1995. Ice-proximal glaciomarine sedimentation and sea-level change in the Inverness area, Scotland: A review of the deglaciation of a major ice stream of the British Late Devensian ice sheet. Quaternary Science Reviews, Vol.14, 289-329. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S084