"The upper boundary is defined by a downward change from mudstones (Woodward and Kimmeridge Clay formations) to the massive, oolitic limestones of the Coralline Formation (Offshore). Geophysical logs show a downward decrease in gamma values and an increase in velocity."@en . "The lower boundary is characterised by a downward change from carbonate-cemented sandstone (Corallian Formation, Offshore) to mudstone (Seeley Formation) and a downward increase in gamma values and decrease in velocity values."@en . . "154.8"^^ . . . "161.5"^^ . "stable"@en . "Corallian Formation (Offshore Areas)"@en . . . . "Limestone and sandstone with subsidiary mudstone. Stratified bedrock. Occurs offshore. Deposited during the Oxfordian Age (Jurassic Period) (161.5-154.8 Ma BP)."@en . . . "CRGR"@en . "Light grey to buff limestone, sandstone and thin mudstone in the Southern North Sea Basin. Limestones are calcite spar cemented oolites with occasional pisolite horizons and abundant bioclastic debris. Sandstones are fine- to medium-grained and variably cemented. 'Raxella' sponge spicules are common. On geophysical logs, the formation forms a funnel-shaped profile where massive limestone are overlain by interbedded, cemented and poorly cemented sandstone. \r\n\r\nA westerly facies change to fine sandstone-, siltstone- and mudstone- dominated deposits (Seeley Formation) takes place on the East Midland Shelf."@en . "Variable in thickness up to a maximum of c. 100 m (in UK wells 47/9-2 and 47/9-3)."@en . "Corallian Formation (Offshore Areas)"@en .