How Fast Is Rock Erosion (mountain)?

Mountains erode at about 1 mm per year on average — through wind, rain, freeze-thaw cycles and chemistry. Softer ranges wear far faster, which is why the ancient Appalachians are now far smaller than the sharper, younger Himalayas to the east.

The Alps lose 1 mm of height per year — but gain 1.5 mm per year. They are still rising.

• Similar pace to fingernails growing
• About 600× slower than grass grows