This is the door said to have inspired Tolkien's Doors of Durin in The Lord of the Rings. The two trees standing on either side of it, at St Edward's Church in Stow-on-the-Wold, are believed to be the ones the Oxford professor placed at the entrance to the Mines of Moria.
In 1916 someone dug a well to find water for irrigation, in the middle of a desert. Scalding water exceeding 200°F, has flowed ever since. Calcium carbonate deposits building up into this cone shape with colourful thermophilic algae.
This is the Fly Geyser.