The underlying rocks are Carboniferous Limestone containing phreatic caves at Shute Shelve Cavern and Picken's Hole from which fossils dating from the Middle Devensian have been recovered.

At the western end of the hills, closest to the M5 motorway, is Crook Peak which reaches 191 metres (627 ft), and forms a prominent feature from the surrounding landscape.

[6] A ridge to the south east of Crook Peak, known as 'The Razor', is used by the West Mendip Soaring Association to fly model aircraft when the wind is a south-westerly, southerly or north-easterly direction.

[9] Around the small village of Cross is Wavering Down House which was, for the last 20 years of his life, the home of the British comedian Frankie Howerd.

[10] The house is now a tourist attraction, and in the summer hosts concerts and opens regularly as a museum of Howerd's collection of memorabilia to raise fund for charities.

[19] Shute Shelve Hill, is largely formed by more resistant Carboniferous Limestone laid down in the Dinantian period about 350 million years ago.

The hill rises to 233 metres (764 ft) above sea levels and represents a ridge formed by the southern Limb of a highly eroded anticline with younger limestones on the lower slopes.

[21] Picken's Hole at the southern end of Crook Peak is considered to be of importance because of its clear, well-stratified sequence of deposits and faunas, all dating from within the Devensian.

[24][25][26] Faunal deposits of spotted hyena, lion, Arctic fox, mammoth, woolly rhinoceros, horse, reindeer, suslik and northern vole (Microtus oeconomus) from approximately 35,000 BP have also been recovered.