Geologists reveal the ‘master sculptor’ behind the world’s dramatic sandstone formations
Arches 'carved' from sandstone are found all over the world
It’s long been thought that the arches, columns and bridges of natural sandstone formations were created by years of erosion from wind and rain, but new research suggests that these fantastic shapes are actually the product of gravity instead.
Scientists from the Charles University of Prague explain that it’s not that erosion doesn’t play its part, but that it is the rock’s “internal stress fields” – the different areas of pressure caused by weight and gravity - that dictate the final form.
“Erosion gets material out, but doesn’t make the shape,” explains Jiri Bruthans, a hydrogeologist who led the research. Instead, he says, the wind and the rain are merely the “tools” that reveal the shape that is latent in the rock.
Dr Bruthans began his research after visiting the Stralec Quarry in the Czech Republic and observing the unusual properties of a type of sandstone known as “rock sand”. Bruthans noticed that although the miners had to use dynamite to break the rock walls apart, once they had the material itself just crumbled apart - often leaving behind the arches and bridges seen in natural sandstone formations.
The team from Prague took away blocks of rock sand from the quarry to conduct their own experiments, exposing the samples to cycles of heat, cold and salt to simulate natural erosion, and even leaving one block out in the rain for 15 months to see if it would form a natural arch.
They found that by placing weights and pressures on the material they could accurately predict how arches, alcoves and other features would form, baking cubes of the rock sand in the oven to harden it then dunking it under water to watch erosion take place.
One of the rock sand cubes and the arch it formed after being squeezed by weights and submerged underwater. Image credit: Marek Janac
"You can control it completely," Dr Bruthans told the BBC. "You select the pillar direction, by choosing the points where you apply the compression. It's just the stress which controls the shape - nothing else."
In an article written to accompany the research in Nature Geoscience, Professor Chris Paola of the University of Minnesota described the discovery as "a lovely and elegant formative mechanism for a lovely and elegant kind of landform".
"These natural sculptures have delighted countless visitors, some of whom must have paused to wonder where they come from," said Professor Paola. "Here is an answer."
- 1 Tidal launch: The most pretentious lines from Alicia Keys' valedictory speech
- 2 Britain First 'acting like Ukip henchmen' by invading meeting of activists in revenge for pub protest against Nigel Farage
- 3 Katie Hopkins attacked me on Twitter — so I reported her to the police for inciting racial hatred
- 4 Tidal: Jay Z's Spotify rival streaming service criticised for making wealthy artists even richer
- 5 Brixton squat flats now costing up to £3k per month show how out of control rent is in London
Ukip supporters are 55 or older, white and socially conservative, finds British Social Attitudes Report
Street preacher quoting from the Bible fined for calling homosexuality an 'abomination'
Woman filmed launching racist tirade against men on the Tube for speaking in 'own lingo'
The West has it totally wrong on Lee Kuan Yew
David Cameron calls Labour 'hopeless, sneering socialists' while announcing 7-day NHS plans
Revealed: Putin's army of pro-Kremlin bloggers
Negotiable: Recruitment Genius: This leading supplier of compliance software a...
£24000 - £30000 per annum: Recruitment Genius: The Associate System Engineer r...
Negotiable: Recruitment Genius: An Executive Assistant is required to join a l...
£45000 - £50000 per annum + benefits : Ashdown Group: A highly successful, glo...