The Danxia formations are situated around 600 miles west of Shanghai, in the Gansu province of China. They stretch for hundreds of miles and some of them are now UNESCO Geoparks, spared from development or over trampling.
The Danxia formations are made predominantly of red-colored sandstones and conglomerates of largely Cretaceous. I can’t really find any description of how or why the colours formed this way, well not any I can understand, but I gather they are strips of sandstone that have been compressed over millions of years.
As for the colours? Who knows. It looks incredible though: