Editing Boulder

{{Short description|Natural rock fragment larger than 10 inches}}
{{About|large rocks|the city in Colorado|Boulder, Colorado|other uses}}
[[Image:Balanced Rock.jpg|thumb|This balancing boulder, "Balanced Rock", stands in [[Garden of the Gods]] park in [[Colorado Springs, CO|Colorado Springs]], Colorado, United States.]]
[[File:Boulder along the chief hike in Stawamus Chief Provincial Park, BC (DSCF7553).jpg|thumb|Boulder in [[British Columbia]], Canada]]
[[File:Kämmenkivi stone in Pisa, Kuopio, Finland.jpg|thumb|''Kämmenkivi'' stone on the Pisa hill in [[Kuopio]], Finland]]
[[File:Bolders on Mahendra Hills, India.jpg|thumb|2'500 Million years old rocks on a hill in [[Hyderabad]], India.]]
In [[geology]], a '''boulder''' (or rarely '''bowlder''')<ref>{{Cite book |title=Webster's New International Dictionary of the English Language |publisher=G. & C. Merriam Company |year=1913 |location=Springfield, Massachusetts}}</ref> is a [[rock (geology)|rock]] fragment with size greater than {{Convert|25.6|cm|in|1|abbr=on}} in diameter.<ref name="Glossary2005">{{cite book | title=Glossary of Geology | publisher=American Geological Institute | editor-last1=Neuendorf | editor-first1=K.K.E. | editor-last2=Mehl | editor-first2=J.P. Jr. | editor-last3=Jackson | editor-first3=J.A. | year=2005 | location=Alexandria, Virginia | page=79 | isbn=978-0922152896| edition=5th }}</ref> 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.<ref name="Boulder">{{cite dictionary|title=Boulder|url=http://dictionary.reference.com/browse/boulder|dictionary=[[Dictionary.com]]|access-date=24 August 2013}}</ref> In common usage, a boulder is too large for a person to move. Smaller boulders are usually just called [[rock (geology)|rock]]s or stones.

== Etymology ==
The word ''boulder'' derives from ''boulder stone'', from [[Middle English]] ''bulderston'' or [[Swedish language|Swedish]] ''bullersten''.<ref>[http://dictionary.reference.com/browse/boulder boulder. (n.d.)] Online Etymology Dictionary. Retrieved December 9, 2011, from Dictionary.com website.</ref>

== About ==
In places covered by [[ice sheet]]s during [[ice age]]s, such as [[Scandinavia]], northern [[North America]], and [[Siberia]], [[glacial erratic]]s are common. Erratics are boulders picked up by ice sheets during their advance, and deposited when they melt.<ref name="Boulder" /> These boulders 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 formation]]s involve giant boulders exposed by [[erosion]], such as the [[Karlu Karlu / Devils Marbles Conservation Reserve|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 [[Clastic rock|clast]]s are found in some [[sedimentary rock]]s, such as coarse [[conglomerate (geology)|conglomerate]] and [[boulder clay]].

==See also==
* [[Bouldering]], [[free climbing]] performed on small rock formations or artificial [[climbing wall]]s
* [[Moeraki Boulders]], unusually large spherical boulders found in [[New Zealand]]
* [[Monolith]], a geological feature consisting of a single massive rock
* [[List of individual rocks]]

==References==
{{Reflist}}

==External links==
{{Commons category-inline|Boulders}}

{{Coastal geography}}
{{Authority control}}

[[Category:Rocks]]
[[Category:Rock formations]]
[[Category:Garden features]]
[[Category:Natural materials]]