| Gray Sandstone Group | |
|---|---|
| Stratigraphic range: Wenlockian (Silurian) | |
 Thick sandstone units of the Gray Sandstone Group outcropping on the coast, just west of Marloes Sands | |
| Type | Group |
| Underlies | Red Marls Formation |
| Overlies | Coralliferous Group |
| Thickness | circa 274 - 609m |
| Lithology | |
| Primary | quartzitic sandstones |
| Other | mudstones |
| Location | |
| Country | Wales |
| 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]