21 July 2014
Sandstone shapes 'forged by gravity'
By Jonathan Webb
Science reporter, BBC News
Geologists have discovered the secret that gives dramatic natural sandstone monuments their shape: gravity.
By studying cubes of sand in the lab, they showed that areas squeezed by vertical stress are protected from erosion, while others wash away.
The process had proved difficult to study, because natural slabs of sandstone erode over millions of years. (...)