# Boulder > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Boulder > Markdown URL: https://mediated.wiki/source/Boulder.md > Source: https://en.wikipedia.org/wiki/Boulder > Source revision: 1346081805 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) Natural rock fragment larger than 10 inches This article is about large rocks. For the city in Colorado, see [Boulder, Colorado](/source/Boulder%2C_Colorado). For other uses, see [Boulder (disambiguation)](/source/Boulder_(disambiguation)). This [balancing boulder](/source/Balancing_rock), "[Balanced Rock](/source/Balanced_Rock)", stands in [Garden of the Gods](/source/Garden_of_the_Gods) park in [Colorado Springs](/source/Colorado_Springs%2C_CO), Colorado, United States. Boulder in [British Columbia](/source/British_Columbia), Canada *Kämmenkivi* stone on the Pisa hill in [Kuopio](/source/Kuopio), Finland Balanced granite boulders at [Hyderabad](/source/Hyderabad), India In [geology](/source/Geology), a **boulder** is a [rock](/source/Rock_(geology)) fragment with size greater than 25.6 cm (10.1 in) in diameter.[1] Smaller pieces are called [cobbles](/source/Cobble_(geology)) and [pebbles](/source/Pebble). While a boulder may be small enough to move or roll manually, others are extremely massive.[2] In common usage, a boulder is too large for a person to move. Smaller boulders are usually just called [rocks](/source/Rock_(geology)) or stones. ## Etymology The word *boulder* derives from *boulder stone*, from [Middle English](/source/Middle_English) *bulderston* or [Swedish](/source/Swedish_language) *bullersten*.[3] It was previously sometimes spelled **bowlder**, which survives as a less common variant spelling.[4][5] ## About In places covered by [ice sheets](/source/Ice_sheet) during [ice ages](/source/Ice_age), such as [Scandinavia](/source/Scandinavia), northern [North America](/source/North_America), and [Siberia](/source/Siberia), [glacial erratics](/source/Glacial_erratic) are common. Erratics are boulders picked up by ice sheets during their advance, and deposited when they melt.[2] These boulders are called "erratic" because they typically are of a different rock type than the [bedrock](/source/Bedrock) on which they are deposited. One such boulder is used as the [pedestal](/source/Pedestal) of [the Bronze Horseman](/source/The_Bronze_Horseman) in [Saint Petersburg](/source/Saint_Petersburg), Russia. Some noted [rock formations](/source/Rock_formation) involve giant boulders exposed by [erosion](/source/Erosion), such as the [Devil's Marbles](/source/Karlu_Karlu_%2F_Devils_Marbles_Conservation_Reserve) in [Australia](/source/Australia)'s [Northern Territory](/source/Northern_Territory), the [Horeke basalts](/source/Horeke_basalts) in [New Zealand](/source/New_Zealand), where an entire [valley](/source/Valley) contains only boulders, and [The Baths](/source/The_Baths) on the island of [Virgin Gorda](/source/Virgin_Gorda) in the [British Virgin Islands](/source/British_Virgin_Islands). Boulder-sized [clasts](/source/Clastic_rock) are found in some [sedimentary rocks](/source/Sedimentary_rock), such as coarse [conglomerate](/source/Conglomerate_(geology)) and [boulder clay](/source/Boulder_clay). ## See also - [Bouldering](/source/Bouldering), [free climbing](/source/Free_climbing) performed on small rock formations or artificial [climbing walls](/source/Climbing_wall) - [Moeraki Boulders](/source/Moeraki_Boulders), unusually large spherical boulders found in [New Zealand](/source/New_Zealand) - [Monolith](/source/Monolith), a geological feature consisting of a single massive rock - [List of individual rocks](/source/List_of_individual_rocks) - [Floaters](/source/Floaters_(geology)) ## References 1. **[^](#cite_ref-Glossary2005_1-0)** Neuendorf, K.K.E.; Mehl, J.P. Jr.; Jackson, J.A., eds. (2005). *Glossary of Geology* (5th ed.). Alexandria, Virginia: American Geological Institute. p. 79. [ISBN](/source/ISBN_(identifier)) [978-0922152896](https://en.wikipedia.org/wiki/Special:BookSources/978-0922152896). 1. ^ [***a***](#cite_ref-Boulder_2-0) [***b***](#cite_ref-Boulder_2-1) ["Boulder"](http://dictionary.reference.com/browse/boulder). *[Dictionary.com](/source/Dictionary.com)*. Retrieved 30 November 2025. 1. **[^](#cite_ref-3)** [boulder. (n.d.)](http://dictionary.reference.com/browse/boulder) Online Etymology Dictionary. Retrieved December 9, 2011, from Dictionary.com website. 1. **[^](#cite_ref-4)** ["bowlder"](https://www.merriam-webster.com/dictionary/bowlder). *[Merriam-Webster.com Dictionary](/source/Merriam-Webster)*. Merriam-Webster. [OCLC](/source/OCLC_(identifier)) [1032680871](https://search.worldcat.org/oclc/1032680871). 1. **[^](#cite_ref-5)** ["Bowlder"](https://www.collinsdictionary.com/dictionary/english/bowlder). Collins English Dictionary. Retrieved 30 November 2025. ## External links Media related to [Boulders](https://commons.wikimedia.org/wiki/Category:Boulders) at Wikimedia Commons v t e Coastal geography Landforms Anchialine pool Archipelago Atoll Avulsion Ayre Barrier island Bay Bight Bodden Brackish marsh Cape Channel Cliff Coast Coastal plain Coastal waterfall Continental margin Continental shelf Coral reef Cove Dune cliff-top Estuary Firth Fjard Fjord Freshwater marsh Fundus Gat Geo Gulf Gut Hapua Headland Inlet Intertidal wetland Island Islet Isthmus Liman Lagoon Machair Mudflat Natural arch Peninsula Reef Ria Salt marsh Shoal Skerry Sound Spit Stack Strait Strand plain Submarine canyon Tidal island Tidal marsh Tide pool Tied island Tombolo Waituna Windwatt Beaches Beach cusps Beach evolution Beach ridge Beach wrack Beaches in estuaries and bays Beachrock Coastal morphodynamics Pocket beach Raised beach Recession Shell beach Shingle beach Storm beach Wash margin River mouths Debouch Mouth bar River delta mega regressive Processes Blowhole Cliffed coast Coastal biogeomorphology Coastal erosion Concordant coastline Current Cuspate foreland Discordant coastline Emergent coastline Feeder bluff Flat coast Graded shoreline Ingression coast Large-scale coastal behaviour Longshore drift Marine regression Marine transgression Raised shoreline Rip current Rocky shore Sea cave Sea foam Shoal peresyp Steep coast Submergent coastline Surf break Surf zone Surge channel Swash Undertow Volcanic arc Wave-cut platform Wave shoaling Wind fetch Wind wave Management Accretion Coastal management Integrated coastal zone management Submersion Related Bulkhead line Coastal engineering Grain size boulder clay cobble granule gravel pebble sand shingle silt Intertidal zone Littoral zone Physical oceanography Region of freshwater influence River plume Category Authority control databases Encyclopedia of Modern Ukraine Yale LUX --- Adapted from the Wikipedia article [Boulder](https://en.wikipedia.org/wiki/Boulder) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Boulder?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.