The natural erosion continues to this day and threatens the soft sand banks of the waterway.

The crater is caused by natural erosion, with rock formations in red, purple and green.

There are several rock formations at the top of the hill which have been formed by natural erosion.

See where the stone is gouged out there looks like natural erosion, but it isn't.

But he conceded that the series had undergone some natural erosion.

Each coat should weather until partly worn off, by chalking or natural erosion.

"It's the natural erosion of these shows," he said.

The camp has suffered bad erosion, both natural and man-made, unsurprisingly for a site which is well over 2000 years old.

Most of the mounds are not visible any more due to natural erosion and ploughing.

The artwork is subject to natural erosion and in due course the area will revert to original desert plain.