If you thought that some of the rocks in the photos for my geology post last week had a greenish tinge to them, then you would have been right. It was actually quite hard to find a good picture of the crystals in the rock. More commonly the surfaces were hidden like this.
Most of the rock surfaces are covered in greenish or grey lichen. There were other colours too.
The lichen thrives because, unlike mainland Britain, the air is very clean and unpolluted. There’s hardly any traffic…
…and plenty of fresh sea air to blow any fumes away.
Lichen love it.