Jim McMahon/Mapman™

Here’s a sight you don’t see every day: multi-colored mountains! Every year, thousands of people travel to Zhangye Danxia (jahng-yeh dan-shyah) National Geological Park in China to marvel at these amazing landforms.

How did the mountains get their stripes? Long ago, water currents laid down sediment, such as sand and silt. The top layer became soil, which later hardened into rock. Soil that forms under different conditions turns different colors. The red layers formed when forests covered the area. The gray layers formed when the area was a swamp. 

The stripes show that the region kept changing over millions of years, says geologist Peter Modreski. If it hadn’t, “the mountains wouldn’t look nearly as pretty!” he says.