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. The formation is made up largely of dolomites but includes siltstones and fine-grained sandstones in its lower parts. It is a sub unit of the Portland Group.
| Portland Sand Formation | |
|---|---|
| Stratigraphic range: Tithonian, | |
| 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 |
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