Jagged tower karst formations rise in the distance as the Li River flows past a quiet landscape near Guilin, China.

These karst mountains are what remain of an ancient seabed that was lifted and subsequently eroded away. The formations line much of the Li River and have inspired Chinese poets and artists for centuries. They're also a source of national pride, earning an appearance on the back of China's 20 yuan note.

(Photo shot on assignment for, but not published in, "Bamboo, The Giant Grass, " October 1980, National Geographic magazine)