| Computer Code: |
RHD |
Preferred Map Code: |
RHD |
| Status Code: |
Full |
| Age range: |
Courceyan Substage (CF)
— Tournaisian Age (CT) |
| Lithological Description: |
Grey, thinly bedded, very fine-grained dolostone, with subordinate beds of dark grey limestone comprising calcilutite and calcisiltite, mudstone, in which fenestral cavities are common, breccias and several thin beds of coarse-grained quartzitic sandstone. The variably bedded argillaceous limestone or dolostone, has a marine fauna of crinoids and brachiopods, alternating with dolostone containing penecontemporaneous breccias, sparse gastropods, serpulid and ostracod fauna. |
| Definition of Lower Boundary: |
The top of a red-brown sandstone, pebbly sandstone and conglomerate of the Redhouse Sandstone Formation, displaying a sharp passage into grey dolostone of the overlying Rue Hill Dolomite Formation. |
| Definition of Upper Boundary: |
A conformable passage into medium grey biosparites or dark grey cherty micrites of the Milldale Limestone Formation, with the boundary at the top of unfossiliferous porcellaneous dolostone above the highest occurrence of the ostracod-gastropod fauna. |
| Thickness: |
Measured as 84.47 m thick in the Caldon Low Borehole. |
| Geographical Limits: |
Off-shelf, to the Derbyshire High and the Staffordshire Shelf, in the subsurface of the Ashbourne and Cheadle district. |
| Parent Unit: |
Peak Limestone Group (PKLM)
|
| Previous Name(s): |
Rue Hill Dolomites [Obsolete Name and Code: Use RHD]
(-1789)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
Caldon Low Borehole (SK04NE/36) displays the entire thickness of formation between 365.07 and 280.6 m. |
| Reference(s): |
| Chisholm, J I, Charsley, T J and Aitkenhead, N. 1988. Geology of the country around Ashbourne and Cheadle. Memoir of the British Geological Survey, Sheet 124 (England and Wales). |
| Aitkenhead, N, and Chisholm, J I. 1982. A standard nomenclature for the Dinantian formations of the Peak District of Derbshire and Staffordshire. Report of the Institute of Geological Sciences, No. 82/8. |
| Welsh, A and Owens, B. 1983. Early Dinantian miospore assemblages from the Caldon Low Borehole, Staffordshire, England. Pollen Spores, vol. 25, 253-264. |
| Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E124
E099
|
