Geography
China's 'Rainbow Mountains' get their stripes from 24 million years of layered sediment
Zhangye Danxia's mountainsides show bands of red, yellow and green rock, built up as different sandstones and mineral-rich layers were laid down over some 24 million years. When the Indian and Eurasian plates collided, the once-flat layers buckled and tilted, exposing this striped cross-section at the surface. Iron oxide gives the red bands their color — the same mineral behind rust.