Misplaced Pages

In geology, a boulder (or rarely bowlder) 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 move. Smaller boulders are usually just called rocks or stones.

Etymology

The word boulder derives from boulder stone, from Middle English bulderston or Swedish bullersten.

About

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. 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 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.

See also

• Bouldering, free climbing performed on small rock formations or artificial climbing walls
• 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

1. Webster's New International Dictionary of the English Language. Springfield, Massachusetts: G. & C. Merriam Company. 1913.
2. 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 978-0922152896.
3. ^ "Boulder". Dictionary.com. Retrieved 24 August 2013.
4. boulder. (n.d.) Online Etymology Dictionary. Retrieved December 9, 2011, from Dictionary.com website.

External links

Media related to 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 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

• Rocks
• Rock formations
• Garden features
• Natural materials