This balancing boulder, "Balanced Rock", stands in Colorado_Springs
,_Colorado,_United_States..html" style="text-decoration: none;"class="mw-redirect" title="Colorado Springs, CO">Colorado Springs, Colorado, United States.">Colorado Springs, CO">Colorado Springs, Colorado, United States.
''Kämmenkivi'' stone on the Pisa hill in [[Kuopio">File:Kämmenkivi stone in Pisa, Kuopio, Finland.jpg|''Kämmenkivi'' stone on the Pisa hill in [[Kuopio
In [[geology ([[Udden–Wentworth scale), a boulder is a [[rock (geology)|rock fragment with size greater than in diameter.
Smaller pieces are called [[cobble (geology)|cobbles and pebble
s. 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 move. Smaller boulders are usually just called rocks
(American English) or stones (In British English a rock is larger than a boulder). The word ''boulder'' is short for ''boulder stone'', from Middle English
''bulderston'' or Swedish
Online Etymology Dictionary. Retrieved December 9, 2011, from Dictionary.com website.
In places covered by ice sheets during Ice Ages, such as Scandinavia, northern North America, and Siberia, glacial erratics are common. Erratics are boulders picked up by ice sheets during their advance, and deposited when they melt.
They are called "erratic" because they typically are of a different rock type than the bedrock on which they are deposited. One such boulder is used as the pedestal of the Bronze Horseman in Saint Petersburg, Russia.
Some noted rock formations involve giant boulders exposed by erosion, such as the Devil's Marbles in Australia's Northern Territory, the Horeke basalts in New Zealand, where an entire valley contains only boulders, and The Baths on the island of Virgin Gorda in the British Virgin Islands.
Boulder-sized clasts are found in some sedimentary rocks, such as coarse conglomerate and boulder clay.
The climbing of large boulders is called bouldering.
* Road debris
* Peñón de Ponce