The BGS Lexicon of Named Rock Units — Result Details

Alston Formation

Computer Code: AG Preferred Map Code: AG
Status Code: Full
Age range: Asbian Substage (CR) — Pendleian Substage (CE)
Lithological Description: Bioclastic limestones, sandstones, mudstones, siltstones and rare coals typically in regular cyclothemic sequence.
Definition of Lower Boundary: At top of Orton Formation: on Alston Block at base of a thin mudstone below Melmerby Scar Limestone; in Cumbria at conformable base of Sixth Limestone.
Definition of Upper Boundary: Overlain conformably by rocks of the Stainmore Formation, the boundary been taken at the top of the Great Limestone Member.
Thickness: c.340m
Geographical Limits: British Geological Survey sheets 23, 24, 31.
Parent Unit: Yoredale Group (YORE)
Previous Name(s): CHIEF LIMESTONE GROUP
LOWER AND MIDDLE LIMESTONE GROUPS
GLEASTON FORMATION
UPPER LIDDESDALE GROUP
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  The area between Bothel and Hesket Newmarket. 
Partial Type Section  (Basal stratotype). Wildboar Scar: Arthurton, R S and Wadge, A J, 1981, pp.33-34. 
Reference Section  Croglin Water sections: Arthurton, R S and Wadge, A J, 1981, pp.45 and 149. Top of Alston Group at NY 634 463. 
Reference(s):
Arthurton, R S and Wadge, A J, 1981. Geology of the country around Penrith. Memoir of the Geological Survey of Great Britain. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E031 E024 E023 E020 E018 E040