Fuller’s Earth Rock – Middle Jurassic (Lead author: PJB)
The Fuller’s Earth Rock (FER) Member is a local limestone within the Fuller’s Earth Formation (Middle Bathonian) of the Great Oolite Group, about 9m thick in the Thornford to Sherborne area and 7-11m in the Purse Caundle area further east. It is seen in buildings in all these locations, including Sherborne Old Castle.
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The FER is a sequence of buff to grey shelly bioturbated argillaceous lime mudstones and calcareous claystones (marls) with some interbedded bioclastic limestones. The top 0.5-0.9m is rich in Ornithellid brachiopods and bivalves. The FER does not extend south of Winterbourne Kingston (borehole) and is absent in the coastal outcrop.
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