Although recent in origin, this area is of considerable value to wildlife as it contains extensive areas of limestone (resulting from the extraction of ironstone) upon which characteristic limestone flora has developed. Limestone grassland is now extremely rare in Northamptonshire.

The cliffs and terraces of the Gullet, with their mixture of grassland types and unstable rocky slopes are rich in butterflies, moths, and beetles. Plants growing on the site include bee orchids, common spotted orchids, wild strawberries and hart’s tongue ferns.

The pond at the south western end of the Gullet is particularly species rich, supporting a number of unusual species of plants and invertebrates. It also contains a colony of the protected great crested newt.

In addition to the ecological interest, the Gullet contains a number of interesting geological features, including box formations in the ironstone and fossil deposits such as lamp shells and oysters.