| Otter Sandstone Formation (OS)[1] | |
| Type: | Formation |
| Age: | Anisian |
| Period: | Anisian |
| Region: | England |
| Country: |  United Kingdom |
| Unitof: | Sherwood Sandstone Group (SSG) |
| Underlies: | In coastal exposures, transitional into overlying Mercia Mudstone. |
| Overlies: | Budleigh Salterton Pebble Beds |
| Thickness: | Coast and Exeter district: ~160m (530feet) Taunton district: 30- |
The Otter Sandstone Formation is an obsolete geological unit in England, now referred to as the Helsby Sandstone Formation.[2] It preserves fossils dated to the Triassic, Anisian period.