| Gray Sandstone Group | |
| Type: | Group |
| Age: | Wenlockian (Silurian) |
| Prilithology: | quartzitic sandstones |
| Otherlithology: | mudstones |
| Country: | Wales |
| Underlies: | Red Marls Formation |
| Overlies: | Coralliferous Group |
| Thickness: | circa 274 - 609m |
| Extent: | south Pembrokeshire |
The Gray Sandstone Group is a late Silurian lithostratigraphic group (a sequence of rock strata) in west Wales. The strata are exposed in the coast around the Milford Haven area; outcrops occur either side of Marloes Bay. Besides quartzitic sandstones and mudstones, sandy rottenstones are found at outcrop. Fossils within the rottenstone beds include brachiopods and corals.[1] The rocks of this group have also previously been known as the Gray Sandstone Series.[2]