Today's Independent has an article about ancient arches which apparently are not the work of erosion but of gravity and internal stresses.
Like Michelangelo's sculptures the figure is already inside waiting to come out.
The expert who discovered this based his findings on Czech quarry workers who blasted rock away leaving arches and other formations.
So, it's not just gravity, it's also people with explosives blasting the rock.
Which brings us to square one so to speak.
'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."
Which seems to suggest that sea arches and other structures could very well be artificial after all.
The first image is a natural sea arch. The second the 'man made laboratory arch'.http://www.independent.co.uk/news/scien ... 18627.html