Why does the mystical Glastonbury Tor rise up out of the surrounding lowlands?

First of all look straight ahead and in the middle distance you’ll see three hills which punctuate the flat landscape. From left to right they are Hay Hill, Ben Knowle Hill and Yarley Hill, part of a low ridge just south of the River Axe.

 Surrounding these hills the Somerset Levels are an area of low-lying farmland. The lowest point is just 0.2 metres above sea level.  Six thousand years ago the levels were not land at all but a shallow lake dotted with higher islands. Glastonbury Tor at over 500 feet is one of these. Its Celtic name was Ynys Wydryn, meaning ‘Isle of Glass’.

In the nineteenth century this boggy area of freshwater fens and salt marshes was artificially drained and the land reclaimed for pasture. Today the low-lying levels make the perfectly conical Glastonbury Tor and the other hills stand out in sharp relief. 

The tor itself is formed of rocks that date back to the early Jurassic Period between 200 and 175 million years ago and was once part of a bigger ridge of rock that crossed the levels. Over time the softer rocks around it have been worn away by weathering (wind, rain, snow and ice) scouring some parts away and leaving other parts standing. Glastonbury Tor has withstood these processes thanks to a tough rock called sandstone.

One of the top layers of rock that make up the tor is sandstone which has acted as a caprock sealing and protecting the lower rocks from erosion. At the bottom of the tor an iron-rich spring infuses the sandstone with iron oxides which in turn make it even more resistant.