The chalk grasslands of Cock Marsh are located near the River Thames, north of Maidenhead in Berkshire.

Some of the plants are: Triglochin palustris (marsh arrowgrass), Hottonia palustris (water violets), Polygonum minus (lesser persicaria), Hydrocotyle vulgaris (marsh pennywort), Oenanthe aquatica (water hemlock), and Salix willow scrub.

[2] Cyperus fuscus (brown galingale), a rare and endangered species of sedge, thrives in the wet areas at Cock Marsh where grazing animals disturb the ground.

[5] A round barrow cemetery, listed as a scheduled monument, is located at Cock Marsh on the flood plain of the River Thames.

Finds included cremation burials, flint tools, pottery, animal bones, part of a shield and a knife.