In
geology, a boulder (or rarely bowlder) is a
rock fragment with size greater than in diameter.
Smaller pieces are called
cobbles
Cobblestone is a natural building material based on cobble-sized stones, and is used for pavement roads, streets, and buildings.
Setts, also called Belgian blocks, are often casually referred to as "cobbles", although a sett is distinct fro ...
and
pebble
A pebble is a clast of rock with a particle size of based on the Udden-Wentworth scale of sedimentology. Pebbles are generally considered larger than granules ( in diameter) and smaller than cobbles ( in diameter). A rock made predominant ...
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 or stones. The word ''boulder'' derives from ''boulder stone'', from the
Middle English ''bulderston'' or
Swedish
Swedish or ' may refer to:
Anything from or related to Sweden, a country in Northern Europe. Or, specifically:
* Swedish language, a North Germanic language spoken primarily in Sweden and Finland
** Swedish alphabet, the official alphabet used by ...
''bullersten''.
boulder. (n.d.)
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
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, and Siberia, glacial erratics are common. Erratics are boulders picked up by ice sheets during their advance, and deposited when they melt.bedrock
In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface mater ...
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
A rock formation is an isolated, scenic, or spectacular surface rock outcrop. Rock formations are usually the result of weathering and erosion sculpting the existing rock. The term ''rock formation'' can also refer to specific sediment ...
s involve giant boulders exposed by erosion, such as the Devil's Marbles
Karlu Karlu / Devils Marbles Conservation Reserve is a protected area in the Northern Territory of Australia located in the locality of Warumungu about south of Tennant Creek, and north of Alice Springs. The nearest settlement is the small to ...
in Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
'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
Conglomerate or conglomeration may refer to:
* Conglomerate (company)
* Conglomerate (geology)
* Conglomerate (mathematics)
In popular culture:
* The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes
** Co ...
and boulder clay.
The climbing of large boulders is called bouldering.
See also
* Moeraki Boulders
The Moeraki Boulders (officially Moeraki Boulders / Kaihinaki) are unusually large spherical boulders lying along a stretch of Koekohe Beach on the wave-cut Otago coast of New Zealand between Moeraki and Hampden. They occur scattered either as i ...
* Monolith
* Udden–Wentworth scale
References
External links
{{Authority control
Rocks
Rock formations
Garden features
Natural materials