In
geologyGeology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
, a
boulder is a
rockIn geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
with
grain sizeParticle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. This is different from the crystallite size, which is the size of a single crystal inside the...
of usually no less than 256 mm (10 inches) 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
stonesIn geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
. The word boulder comes from
Middle EnglishMiddle English is the stage in the history of the English language during the High and Late Middle Ages, or roughly during the four centuries between the late 11th and the late 15th century....
"
bulder" which was probably of Scandinavian origin such as dialectal
SwedishSwedish is a North Germanic language, spoken by approximately 10 million people, predominantly in Sweden and parts of Finland, especially along its coast and on the Åland islands. It is largely mutually intelligible with Norwegian and Danish...
"
bullersten" meaning "
noisy stone" (Imagine a large stone in a
streamA stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...
, causing
waterWater is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
to roar around it) from "
bullra" (to roar, cf.
DutchDutch is a West Germanic language and the native language of the majority of the population of the Netherlands, Belgium, and Suriname, the three member states of the Dutch Language Union. Most speakers live in the European Union, where it is a first language for about 23 million and a second...
"
bulderen", with the same meaning) and "
sten" (stone).
In places covered by
ice sheetAn ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² , thus also known as continental glacier...
s during
Ice AgeAn ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
s, such as
ScandinaviaScandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
, northern
North AmericaNorth America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, and
RussiaRussia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
,
glacial erraticA glacial erratic is a piece of rock that differs from the size and type of rock native to the area in which it rests. "Erratics" take their name from the Latin word errare, and are carried by glacial ice, often over distances of hundreds of kilometres...
s are common. Erratics are boulders picked up by the ice sheet during its advance, and deposited during its retreat. They are called "erratic" because they typically are of a different rock type than the
bedrockIn stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
on which they are deposited. One of them is used as the
pedestalPedestal is a term generally applied to the support of a statue or a vase....
of
the Bronze HorsemanThe Bronze Horseman is an equestrian statue of Peter the Great in Saint Petersburg, Russia. Commissioned by Catherine the Great, it was created by the French sculptor Étienne Maurice Falconet. It is also the name of a narrative poem written by Aleksandr Pushkin about the statue in 1833, widely...
in
Saint PetersburgSaint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...
, Russia.
Some noted
rock formationThis is a list of rock formations that include isolated, scenic, or spectacular surface rock outcrops. These formations are usually the result of weathering and erosion sculpting the existing rock...
s involve giant boulders exposed by
erosionErosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
, such as the Devil's Marbles in
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
's
Northern TerritoryThe Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
, the
Wairere BouldersThe Wairere Boulders are an unusually large assemblage of basalt boulders in the Hokianga, in the far north of New Zealand. The boulder area, surrounded by subtropical rainforest, has been transformed into a park area to enable visitors to view this oddity of nature...
in
New ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, where an entire
valleyIn geology, a valley or dale is a depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge.The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys...
contains only boulders, and
The BathsThe Baths is a beach area on the island of Virgin Gorda among the British Virgin Islands in the Caribbean.-Geography:"The Baths" are situated about 1,2 miles south off the maintown Spanish Town at the southern tip of the island between Spring Bay and Devil's Bay."The Baths" are an area of unique...
on the island of
Virgin GordaVirgin Gorda is the third-largest and second most populous of the British Virgin Islands . Located at approximately 18 degrees, 48 minutes North, and 64 degrees, 30 minutes West, it covers an area of about...
in the
British Virgin IslandsThe Virgin Islands, often called the British Virgin Islands , is a British overseas territory and overseas territory of the European Union, located in the Caribbean to the east of Puerto Rico. The islands make up part of the Virgin Islands archipelago, the remaining islands constituting the U.S...
.
The
climbingClimbing is the activity of using one's hands and feet to ascend a steep object. It is done both for recreation and professionally, as part of activities such as maintenance of a structure, or military operations.Climbing activities include:* Bouldering: Ascending boulders or small...
of large boulders often requires months or even years of practice, and has given rise, since the late 19th century, to the sport of
boulderingBouldering is a style of rock climbing undertaken without a rope and normally limited to very short climbs over a crash pad so that a fall will not result in serious injury. It is typically practiced on large natural boulders or artificial boulders in gyms and outdoor urban areas...
.