Stone in Archaeology Database


Ham Hill Stone

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Local Name(s): Ham Hill Stone,
North Perrott Stone.
Example of Ham Hill Stone
Stone Group: Sedimentary
Stone Type: Limestone
Geology:
Era:   Mesozoic
Period:   Jurassic
Epoch:   Lower
Geological Sub-Divisons:

Top of Toarician stage of the Upper Lias. Bridport Sand Formation (Yeovil Sands).

General Colour Description:

A distinctive golden/brown colour often with a mottled appearance. It can also be a variable grey or buff colour.

Hand Specimen Description:

A current bedded, medium to coarse grained limestone composed almost entirely of a lenticular mass of small fossil shell fragments bound together by a strongly ferruginous calcareous cement. Two beds are worked, a 'Yellow Bed' which is a pale brown or buff colour, the most distinctive and well known, and a 'Grey Bed' darker in colour and more durable.

Petrographic Description:

Abundant well cemented mass of small broken shell fragments such as pectens, oysters, brachiopoda and echinodermata etc. These shells are cemented with calcium carbonate, limonite and iron hydroxide (goethite). It is also very slightly oolitic and can comprise tiny rare grains of quartz (30 microns in size).

Stone Identifiers: Fossiliferous.
Reacts dilute to HCl? Yes