Portland Sand Formation

The Portland Sand Formation is a limestone formation from the Tithonian stage of the Jurassic period on the Isle of Portland, Dorset, England.[1] The formation is made up largely of dolomites but includes siltstones and fine-grained sandstones in its lower parts.[2] It is a sub unit of the Portland Group.[3]

Portland Sand Formation Stratigraphic range: Tithonian, 152 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Group
Unit of	Portland Group
Underlies	Portland Stone Formation
Overlies	Kimmeridge Clay Formation
Thickness	up to 40 metres (130 ft)
Lithology
Primary	Dolomite
Other	Siltstone, limestone and sandstone
Location
Region	England
Country	UK
Extent	Dorset
Type section
Named for	Isle of Portland
Location	Clay Ope, West Weare Cliff, Isle of Portland
Thickness at type section	30 m

References

1. British Geological Survey. "Portland Sand Formation". BGS Lexicon of Named Rock Units. Retrieved 29 June 2020.
2. Barton et al., 2011 Geology of south Dorset and south-east Devon and its World Heritage Coast. Special memoir of the British Geological Survey. Sheets 328, 341/2, 342/3 and parts of 326/340, 327, 329 and 339 (England and Wales)
3. Callomon, J H and Cope, J C W. 1995. The Jurassic geology of Dorset. 51-103 in Taylor, P D (Editor), Field Geology of the British Jurassic. (Bath: The Geological Society.)