sandstone

The overlying rock, sometimes clay or sandstone, will then suddenly collapse into the depression beneath - called a 'collapse sinkhole'.

The statue - which was first unveiled in 1874 - was previously targeted in February last year, when it was covered with red paint and had parts of its sandstone damaged.

Across several centuries, dozens of different families made their home among what began as a couple of sandstone caves in picturesque Kinver Edge, a high heath with views for miles.

Mr Johnson, also from Bradford, worked with Delph sandstone and gritstone, which is known for its high silica content.

Hike back down the Beach Trail from the visitors center through chaparral and sandy bluffs to the shore at Flat Rock, where rain has eroded deep arroyos into the 300-foot sandstone escarpments.