Stone in Archaeology Database


Chilmark Stone

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Local Name(s): Chilmark Stone. Example of Chilmark Stone
Stone Group: Sedimentary
Stone Type: Limestone
Geology:
Era:   Mesozoic
Period:   Jurassic
Epoch:   Upper
Geological Sub-Divisons:

Upper Jurassic, Portland Beds, Portland Group.

General Colour Description:

Drab greenish grey. Creamy white when first extracted, the presence of specks of glauconite gives it a greenish tinge when exposed to the weather (Clifton-Taylor & Simmons 1987: 71).

Hand Specimen Description:

An oolitic, sandy, fine grained, glauconitic limestone. At Chilmark many individual beds were named including the Trough Bed, Hard or White Bed, Green Bed, Pinney Bed and the Fretting Bed. Of these, the 'Trough Bed' is almost a pure limestone, hard, siliceous and very fossiliferous, it is the best building stone (frequently available underground). It was used for steps and paving. The Green Bed and Pinney Bed are siliceous limestones containing a considerable amount of glauconite and a quantity of sponge spicules, these were softer beds, often used for masonry.

General Comments:

Chilmark stone and Tisbury stone are difficult to distinguish apart.

Stone Identifiers: Glauconitic,  Calcareous,  Fossiliferous,  Oolitic.
Reacts dilute to HCl? Yes