|To me, this looks like the folds of some|
nubby cloth. But it's lava! It dried in
beautiful patterns like this after an
1865 volcanic eruption on the Island of
Santiago (aka San Salvador) in the Galapagos.
Darwin never got to see this, since it
happened 30 years after he visited the islands.
[To see more monochromes, visit Dragonstar's meme.]