| Computer Code: |
AYLS |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Asbian Substage (CR)
— Brigantian Substage (CX) |
| Lithological Description: |
Comprises mudstones, interbedded with limestones, sandstones and tuffs and subordinate coals and seatearths. At the type locality the basal 43 m of the formation is dominated by grey or brown calcareous mudstone with several thin beds of impure grey or dark grey limestone and in the upper part thin beds of yellow-brown tuff and tuffaceous limestone and mudstone. Above this, a 52 m thick succession comprises brown mudstone and calcareous mudstone and includes at least three coals and a 21 m thick succession of white or pale yellow coarse-grained and feldspathic sandstones with thin interbeds of siltstone or mudstone, informally referred to as the Astbury Sandstone. |
| Definition of Lower Boundary: |
The base of the formation is taken at the conformable base of the mudstone-rich succession with subordinate limestone above the limestone-dominated succession of the Bowsey Wood Formation. |
| Definition of Upper Boundary: |
The top of the formation is taken at the top of the mudstone-dominated succession with subordinate limestones and sandstones, overlain conformably by the dark grey mudstone of the Bowland Shale Formation. |
| Thickness: |
Up to 100 m thick. |
| Geographical Limits: |
The formation occurs above the northern part of the Market Drayton Horst. The formation is limited in outcrop to a small inlier, about 1km long and 300m wide, at Limekiln Farm, Astbury [SJ 86 59]. |
| Parent Unit: |
Peak Limestone Group (PKLM)
|
| Previous Name(s): |
Astbury-Limestone-Shales
(-664)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Partial Type Section |
Small disused quarry near Limkiln Farm, Astbury. The section, seen to be 10.3 m thick, is from the lower part of the formation, below the Astbury Sandstone [Evans et al., 1968] |
| Reference(s): |
| Evans, W B, Wilson, A A, Taylor, B J and Price, D. 1968. Geology of the country around Macclesfield, Congleton, Crewe and Middlewich. Memoir of the Geological Survey of Great Britain, Sheet 110 (England and Wales). |
| Earp, J R and Calver, M A. 1961. Exploratory boreholes in the North Staffordshire Coalfield. Bulletin of the Geological Survey of Great Britain, Vol. 17, 153-190. |
| Rees, J G and Wilson, A A. 1998. Geology of the country around Stoke-on-Trent. Memoir of the British Geological Survey, Sheet 123 (England and Wales). |
| Waters, C N, Barclay, W J, Davies, J R and Waters, R A. In press. Stratigraphical framework for Carboniferous successions of Southern Great Britain (Onshore). British Geological Survey Research Report, RR/05/06. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E110
|
