The BGS Lexicon of Named Rock Units — Result Details
Ida Formation
| Computer Code: | IDA | Preferred Map Code: | notEntered |
|---|---|---|---|
| Status Code: | Full | ||
| Age range: | Pliensbachian Age (JE) — Pliensbachian Age (JE) | ||
| Lithological Description: | The Ida Formation consists of thinly interbedded brown to grey siltstones, fine sandstones and argillaceous, occasionally oolitic (chamositic) and carbonaceous, limestones. | ||
| Definition of Lower Boundary: | The lower boundary is defined by an abrupt downward transition from sandy and calcareous sediments to mudstones (Offa Formation). It coincides with an increase in gamma values and a decrease in velocity, which may be marked in some wireline logs. | ||
| Definition of Upper Boundary: | The boundary is characterised by a downward change from mudstones (Cerdic Formation) to harder, sandy and calcareous, interbedded sequence of the Ida Formation. There is a sharp downward decrease in gamma values and an increase in velocity. | ||
| Thickness: | Up to c. 30 m. | ||
| Geographical Limits: | Southern North Sea Basin (quadrants 41-43, 46-49, 51-53). | ||
| Parent Unit: | Lias Group (LI) | ||
| Previous Name(s): | Lias Group
(LI)
|
||
| Alternative Name(s): | Marlstone Rock Formation Cleveland Ironstone Formation Charmouth Mudstone Formation Staithes Sandstone Formation |
||
| Stratotypes: | |||
| Type Section | North Sea well 47/29a- 1 between 590 and 607 m (Lott and Knox, 1994). | ||
| Reference Section | North Sea well 42/24- 1 between 541 and 559 m (Lott and Knox, 1994). | ||
| Reference Section | North Sea well 48/18c- 5 between 1030 and 1066 m (Lott and Knox, 1994). | ||
| Reference Section | North Sea well 53/01- 3 between 912.5 and 929 m (Lott and Knox, 1994). | ||
| Reference(s): | |||
| Lott, G K and Knox, R W O'B. 1994. 7. Post-Triassic of the Southern North Sea. In: Knox, R W O'B and Cordey, W G (eds.) Lithostratigraphic nomenclature of the UK North Sea. British Geological Survey, Nottingham. | |||
| 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: | |||
| none recorded or not applicable | |||