People have been fascinated by Ham Hill’s unique geology for millennia.
It is one of the most geological sites in Somerset, as it is the only place in the world where you can find hamstone, the beautiful golden rock that makes up the top of the hill. The layer of hamstone is actually quite thin. It is like a cap, sitting on top of another layer of Yeovil Sands. This raised plateau of hamstone has created the Ham Hill we see today.
Hamstone is a Jurassic Shelley limestone comprised of crushed up fragments of shells and other sea creatures, all cemented together by calcium carbonate. The fossils found in the rock include ammonites, from which we know the stone to be 170 million years old. From studying the rock geologists can also tell that hamstone was formed under a warm, shallow sea that was subject to strong currents and crashing waves.
Hamstone has been quarried for centuries, but reached its heyday in Victorian times. All of the villages around the hill are built of hamstone and it gives the area its unique character. Notable buildings both near and far have incorporated hamstone; Montacute House, Exeter Cathedral, Sherborne Castle and even the Houses of Parliament use this beautiful stone. Nowadays, hamstone is exported all over the world.
In the past, working the stone was a difficult job. Pick marks, mostly from Victorian times, can still be seen on some rock faces. Explosives cannot be used to quarry hamstone, as the stone would shatter. Today, the stone is quarried using heavy plant machinery, but the carving work that can be seen on hamstone sculptures and window panes is still the work of a skilled stonemason.
There is open access to several old quarry faces on Ham Hill, some of which are part of the Regionally Important Geological Site (RIGS) and geological Site of Special Scientific Interest (SSSI) designations. To see the full extent of the SSSI area at Ham Hill, visit the Natural England SSSI Website. These important designations ensure that the hamstone is reserved for many years to come, and allows geologists and palaeontologists to study it.
To find out more about the fascinating geology of Ham Hill, check out the free booklet Ham Hill: The Rocks and the Quarries, written by local geologist and one of Ham Hill’s dedicated volunteers Hugh Prudden. You can find a copy at the Ham Hill Ranger’s Office, and the Heritage and Tourist Information Centre in Yeovil.