Boulder
60784
225185238
2008-07-12T09:59:20Z
Darwinek
107928
.commonz
{{otheruses1|the large rocks}}
[[Image:Balanced Rock.jpg|thumb|right|250px|This balancing boulder, "'''Balanced Rock'''" stands in [[Garden of the Gods]] park in [[Colorado Springs, CO]].]]
[[Image:Ffionphort cracked granite boulder.jpg|thumb|left| Boulder]]
In [[geology]], a '''boulder''' is a [[rock (geology)|rock]] with [[Particle size|grain size]] of usually no less than 256 mm (10 [[inch]]es) diameter. 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]] or [[Rock (geology)|stones]]. The word boulder comes from [[Middle English]] "''bulder''" which was probably of [[Scandinavian languages|Scandinavian]] origin such as dialectal [[Swedish language|Swedish]] "''bullersten''" meaning "''noisy stone''" (Imagine a large stone in a [[stream]], causing [[water]] to roar around it) from "''bullra''" (to roar, cf. [[Dutch language|Dutch]] "''bulderen''", with the same meaning) and "''sten''" (stone).
In places covered by [[ice sheet]]s during [[Ice Age]]s, such as [[Scandinavia]], northern [[North America]], and [[Russia]], ice has moved and formed [[granite]] boulders, also named [[glacial erratic]]s. One of the largest is used as the [[pedestal]] of [[the Bronze Horseman]] in [[Saint Petersburg]], Russia.
Some noted [[rock formation]]s involve giant boulders exposed by [[erosion]], such as the [[Devil's Marbles]] in [[Australia]]'s [[Northern Territory]], the [[Wairere Boulders]] in [[New Zealand]], where an entire [[valley]] contains only boulders, and [[The Baths]] on the island of [[Virgin Gorda]] in the [[British Virgin Islands]].
The [[climbing]] of large boulders often requires developing special abilities, and has given rise, since the late 19th century, to the sport of [[bouldering]].
{{commonscat|Boulders}}
[[Category:Rocks]]
[[es:Bloque (roca)]]
[[lt:Riedulys]]
[[ja:巨礫]]
[[ru:Валуны]]
[[uk:Валуни]]