Keele Research Repository

This study is an integrated facies analysis of the Forest Marble Formation (Upper Bathonian Middle Jurassic) in the area between Bradford-on-Avon and the Dorset coast (Southern England).
The Forest Marble is a mixed carbonate/clastic shallow marine sequence between about 20m and 30m thick. It is characterised by very rapid vertical and lateral facies changes and so has not been formally subdivided into members. The stratigraphic setting and chronostratigraphy of the Formation are described in Chapter One.
The Formation has been divided into four Facies Associations, described in Chapters 2, 3, 4 and 5. Association A (Marl—dominated Facies Association) is considered to have been deposited around or slightly above normal wave base. Association B (Hardgrounds and Firmgrounds Facies Association) is interpreted as representing periods of depositional hiatus during which substrates hardened to varying degrees allowing the development of benthic communities dominated by epifauna. Association C (Calcirudites Facies Association) is composed largely of coarse shell debris interpreted as representing a series of shallow marine shoals, shell sheets, sandwaves and channels formed in conditions influenced by both waves and tides. Association D (Heterolithic Facies Association) is composed of mixed sand and marl lithologies with rare developments of faunas and is thought to have deposited in very shallow, possibly somewhat restricted, marine conditions.
Chapter Six is an interpretation of the Formation as a whole based largely on the interpretation and spatial distribution of the Facies Associations. It is considered to represent a shallowing upwards regressive sequence deposited between the London Landmass and the Channel Basin.