The theory is that this spring hardened an area of rock which then resisted erosion. The Tor lies on a fault line in the geology where a natural spring, the Chalice Well, brings minerals to the surface. The top of the Tor is formed from Bridport Sands and is underlain by clays and limestones deposited during the Jurassic period 208 to 146 million years ago.

Whilst geologists are not entirely sure why the Tor has survived the erosion of the land around it they do agree that it is a natural feature. The Isle of Avalon, the Holy Thorn and Glastonbury are surrounded by myth and legend. On its summit stands St Michael’s tower, which adds further to the dramatic effect of the Tor at sunrise, sunset and on misty mornings. At 158 metres it rises high above the Avalon Marshes and can be seen from across the county and beyond. Glastonbury Tor Glastonbury Tor and the Avalon Marshes – Copyright Alamy – Glastonbury Tor, on the mystical “Isle of Avalon”, is a truly iconic feature of Somerset’s landscape.

Glastonbury tor avalon