Boulder
Videos
In geology, a boulder is a rock fragment with size greater than 25.6 cm in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others
This balancing boulder, "Balanced Rock", stands in Garden of the Gods park in Colorado Springs, Colorado, United States.
Boulder in British Columbia, Canada
Kämmenkivi stone on the Pisa hill in Kuopio, Finland
Balanced granite boulders at Hyderabad, India
Pebble
Videos
A pebble is a clast of rock with a particle size of 4–64 mm based on the Udden-Wentworth scale of sedimentology. Pebbles are generally considered larger than granules and smaller than cobbles. Pebble
Boulder
…In geology, a boulder is a rock fragment with size greater than 25.6 cm (10.1 in) in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In common usage, a boulder is too large for a person to…
Close view of pebbles
Differently sized rocks and pebbles on a beach in northern England
Pebbles on a riverbank
A walkway decorated with pebbles set into concrete