It is a ridge of chalk grassland, some 1.5 kilometres (1 mi) in length, and forms the boundary between the civil parishes of Kilmington to the south and Maiden Bradley to the north.

It forms a ridge that runs east and west for about a mile, and is 60 m (200 ft) higher than the surrounding land.

The south-facing slope has a mosaic of longer and shorter turfs and has a mixture of grasses, sedges and forbs.

Common valerian is an unusual species to find on chalk soils, and other herbs include autumn gentian, fairy flax and an abundance of devil's-bit scabious.

[2] Long Knoll is categorised as a Marilyn, a hill with topographic prominence of at least 150 metres (492 ft).