The most unnerving landscape I'd encountered so far was the Salt Flats in southern Bolivia, understood to be the largest in the world. The salt is up to 15 metres deep, and has the appearance of thick ice.
We climbed up here, to over 4,600 metres, from Chile, and the change in altitude was pretty unpleasant to begin with, but fine after a day.
These pictures show the surface just before sunrise and then the sunrise itself a little later.
We found a football from somewhere, too.
Stupidly, I have sent the rest of my Bolivia photos home, so this section will have to be finished when I get back.