| Computer Code: |
OSTD |
Preferred Map Code: |
OlO |
| Status Code: |
Full |
| Age range: |
Oxfordian Age (JO)
— Oxfordian Age (JO) |
| Lithological Description: |
Ooidal limestone, yellow to grey, bioclastic, spicule-rich, sandy, grainstone to wackestone textures, cross-bedded in part. |
| Definition of Lower Boundary: |
Erosive non-sequence: ooidal limestone resting sharply on yellow sandstone of Osgodby Formation, or grey-green micaceous siltstone of Oxford Clay Formation. |
| Definition of Upper Boundary: |
Passage upward through decrease in ooid content and increase in fine-grained sand into Rievaulx Member. |
| Thickness: |
Up to 11m. |
| Geographical Limits: |
Between Roulston Scar and Shaw's Moor, southern Hambleton Hills, North Yorkshire. Passes north-east into siliceous sponge spicule-rich limestone (lower part of Rievaulx Member, Wright, 1983). |
| Parent Unit: |
Lower Calcareous Grit Formation (LCG)
|
| Previous Name(s): |
Oolitic limestone in Lower Calcareous Grit [Obsolete Name and Code: Use OSTD]
(-1746)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
Crag at Raven's Gill, Oldstead, North Yorkshire, exposes 11m of ooid-limestone and slightly ooidal, sandy limestone, non-sequentially overlying the Osgodby Formation, and overlain by fine-grained sandstone of the Rievaulx Member (Lower Calcareous Grit Formation). Powell et al., 1992, p. 65; Wright, 1983, p. 261. |
| Reference(s): |
| Wright, J K, 1980. Oxfordian Correlation Chart. "In" Cope, C J W, (Editor). A correlation of Jurassic rocks in the British Isles, Part two: Middle and Upper Jurassic. Geological Society of London Special Report No.15. (p.61-76 in Correlation Chart). |
| Wright, J K. 1983. The Lower Oxfordian (Upper Jurassic) of North Yorkshire. Proceedings of the Yorkshire Geological Society, Vol. 44, 249-281. |
| Powell, J H, Cooper, A H C and Benfield, A C. 1992. Geology of the country around Thirsk. Memoir of the British Geological Survey, Sheet 52 (England and Wales). |
| Fox-Strangways, C. 1892. The Jurassic Rocks of Britain, Vol.1. Yorkshire. Memoir of the Geological Survey of the United Kingdom. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E052
|
