Twywell Gullet is a former ironstone quarry which has deep cuttings with steeply sloping banks. It has species-rich limestone grassland on the slopes and ponds and scrub in the bottoms. There are a number of uncommon ground nesting bees and wasps, and beetles include the nationally rare ruddy darter.[4] There is a large pond which has a large reedbed and many great crested newts.
Footpaths go through the site but there is no access to some steeply sloping areas.