Boulder

A Boulder is a large rock, greater than 256mm (10") in diameter. Some boulders are small enough to move or roll manually, while others are extremely massive. Many famous rock formations involve giant boulders exposed by erosion, for example the Devil's Marbles.

insert list of named formations here

A jumble of large rocks and small boulders in an Australian creekbed

Some people choose to climb larger-sized boulders for recreational purposes or as a method of training for mountaineering and free climbs[?]. This practice is known as bouldering.

Example of an extremely large boulder - note size of tree for comparison.

There are several towns in America named Boulder or with boulder in their names. See

• Boulder, Colorado
• Boulder, Utah
• Boulder City, Nevada.