Dorset's Important Geological Sites

Swanworth Quarry

Swanworth Quarry SY968.783

Swanworth Quarry
Site description: Working quarry.

Geology: Jurassic, Portland Sand, Portland Limestone and Lower Purbeck Beds. The most complete section on the Isle of Purbeck from the Portland Sand on the quarry floor, through the Cherty Series and Freestone Series (Dancing Ledge and Winspit Member of Townson) of the Portland Limestone and into the Lower Purbeck.

The Lower Purbeck exposed here consists of the lower evaporitic limestone, with 9m of blue shale in which insects have been found. The Portland Freestone Series includes the Shrimp Bed containing crustaceans; the Titanites Bed, also known as the Blue Bed containing a rich ammonite fauna; and the Pond Freestone and Under Freestones. Below this is a 25m section of the Cherty Series, with the chert veins more frequent towards the base. The Portland Sand is a dark coloured dolomitic sand, only rarely exposed.

Access: The number of visits per year is limited, since parties must be accompanied by a member of staff, and are thus restricted to working hours, Monday to Friday. By prior arrangement, e-mail us for contact details.

The Lower Purbeck is not accessible at present, but may be so occasionally in the next 10 years, according to the progress of quarrying operations.

Parking: Coach or several cars can be accommodated.

Size of party: 20

Education level: A level/University

Swanworth Information