| Computer Code: |
DBL |
Preferred Map Code: |
DBL |
| Status Code: |
Full |
| Age range: |
Asbian Substage (CR)
— Asbian Substage (CR) |
| Lithological Description: |
The Danny Bridge Limestone Formation consists of pale to mid grey biosparites and biopelsparites (mainly wackestone, with packstone and minor grainstone), and subordinate mudstone in 10 regularly spaced interbeds. Palaeokarst surfaces overlain by bentonitic clays, palaeosols and calcareous laminated crusts are common and the formation displays a characteristically stepped landscape.
Shallow marine carbonates (emergent at times). Late Asbian. |
| Definition of Lower Boundary: |
The base of the formation is conformable on the dark grey limestone of the Garsdale Limestone Formation. |
| Definition of Upper Boundary: |
The cross-bedded, regressive sandstones of the Wintertarn Sandstone Member (WTRS), marking the base of the Tyne Limestone Formation, Yoredale Group, overlie the top of the Danny Bridge Limestone Formation. |
| Thickness: |
The formation is 102-168 m thick, the greatest thickness being on the southern margin of the Askrigg Block (see Dunham and Wilson, 1985). |
| Geographical Limits: |
Askrigg Block, Wensleydale and Wharfedale. The formation is the direct equivalent of the Knipe Scar and Urswick limestone formations of the Stainmore Trough and south Cumbria respectively. |
| Parent Unit: |
Great Scar Limestone Group (GSCL)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
The type section of the formation is the River Clough at Garsdale [SD 7000 9118 to 6977 9128], which consists mainly of marine limestone (biomicrite, biomicrosparite, biosparite) and mudstone (see Burgess, 1986, pp. 13-14). |
| Reference Section |
Beckermonds Scar Borehole (BGS Registration Number SD88SE/1) [SD 8636 8016] from about 8.0 to 101 m depth with mainly pale grey (and subordinate mid grey) limestone, thin mudstone or siltstone beds, and a section of mineralised flats (see Wilson and Cornwell, 1982, pp. 61-63; Dunham and Wilson, 1985, fig. 5, col. 5). |
| Reference Section |
BGS Raydale Borehole (BGS Registration Number SD98SW/1) [SD 9626 8474] from about 5 to 103 m depth. Dunham and Wilson (1985, fig. 5, col. 7) summarised the Raydale Borehole and surface exposures as a largely complete sequence about 127 m thick with mainly pale grey limestone and thin mudstone or siltstone beds. |
| Reference(s): |
| Dunham, K C, and Wilson, A A. 1985. Geology of the Northern Pennine Orefield. Volume 2 Stainmore to Craven. Economic Memoir of the British Geological Survey, Sheets 40, 41 and 50, and parts of Sheets 31, 32, 51, 60 and 61(England and Wales). |
| Dean, M T, Browne, M A E, Waters, C N and Powell, J H. 2011. A lithostratigraphical framework for the Carboniferous successions of northern Great Britain (onshore). British Geological Survey Research Report, RR/10/007. 165pp. |
| Burgess, I C. 1986. Lower Carboniferous sections in the Sedbergh district, Cumbria. Transactions of the Leeds Geological Association, Vol. 11, 1-23. |
| Wilson, A A and Cornwell, J D. 1982. The Institute of Geological Sciences borehole at Beckermonds Scar, North Yorkshire. Proceedings of the Yorkshire Geological Society, Vol.44, 59-88. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E051
E040
E049
|
