The BGS Lexicon of Named Rock Units — Result Details
Coralline Crag Formation
| Computer Code: | CCG | Preferred Map Code: | CCG |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Pliocene Epoch (NP) — Gelasian Age (Q2G) | ||
| Lithological Description: | Carbonate-rich skeletal sands. The acid-insoluble sand fraction is moderately- to poorly-sorted medium-grained sand, the mud content is low. Basal lag gravel rich in pebbles of phosphatic mudstone largely derived from the Thames Group. | ||
| Definition of Lower Boundary: | Rests unconformably on the undulose, possibly tidally-scoured, surface of the Thames Group throughout its known distribution. | ||
| Definition of Upper Boundary: | Overlain unconformably by rocks of the Norwich Crag Formation across most of its extent, but Red Crag Formation material is banked against a buried ridge of the Coralline Crag in some areas and thin Red Crag deposits overlie the Coralline Crag locally. | ||
| Thickness: | c.25m maximum onshore. | ||
| Geographical Limits: | Restricted to southeast Suffolk, around Orford and Aldeburgh, as far north as Thorpeness and just into the adjacent offshore area. There are isolated outliers at Ramsholt and Tattingstone. | ||
| Parent Unit: | Crag Group (CRAG) | ||
| Previous Name(s): | Coralline Crag [Obsolete Name and Code: Use CCG]
(-3283)
|
||
| Alternative Name(s): | Aldeburgh Member Ramsholt Member Sudbourne Member |
||
| Stratotypes: | |||
| Type Area | Pits around Aldeburgh, Sulffolk. Balson et al., 1993. | ||
| Reference(s): | |||
| Balson, P S, Mathers, S J, and Zalasiewicz, J A. 1993. The lithostratigraphy of the Coralline Crag (Pliocene) of Suffolk. Proceedings of the Geologists' Association, Vol. 104, 59-70. | |||
| Balson, P S. 1989. Tertiary phosphorites in the southern North Sea Basin: origin, evolution and stratigraphic correlation, 51-70 in Herriet, J P, and de Moor, G (editors). The Quaternary and Tertiary geology of he Southern Bight, North Sea. Ministry of Economic Affairs, Belgium Geological Society. | |||
| Balson, P S. 1990. The Neogene of East Anglia - a field excursion report. Tertiary Research, Vol. 11, 179-189. | |||
| Balson, P S, and Cameron, T D J. 1985. Quaternary mapping offshore East Anglia. Modern Geology, Vol. 9, 221-239. | |||
| Moorlock, B S, Hamblin, R J O, Morigi, A N, Booth, S J and Jeffery, D H. 2000a. The geology of the country around Lowestoft and Saxmundham. Memoir of the British Geological Survey, sheets 176 and 191 (England and Wales). | |||
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: | |||
| E208 E225 E191 E207 E224 E242 | |||