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Boulder
In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than 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. The word ''boulder'' derives from ''boulder stone'', from the Middle English ''bulderston'' or Swedish ''bullersten''. Online Etymology Dictionary. Retrieved December 9, 2011, from Dictionary.com website. In places covered by ice sheets during s, such as |
Glacial Erratic
A glacial erratic is glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by glacial ice, often over distances of hundreds of kilometres. Erratics can range in size from pebbles to large boulders such as Big Rock () in Alberta. Geologists identify erratics by studying the rocks surrounding the position of the erratic and the composition of the erratic itself. Erratics are significant because: *They can be transported by glaciers, and they are thereby one of a series of indicators which mark the path of prehistoric glacier movement. Their lithographic origin can be traced to the parent bedrock, allowing for confirmation of the ice flow route. *They can be transported by ice rafting. This allows quantification of the extent of glacial flooding resulting from ice dam failure which release the waters stored in proglacial lakes such as Lake Missoula. Erratics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karlu Karlu / Devils Marbles Conservation Reserve
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 town of Wauchope located to the south. The Devils Marbles are of great cultural and spiritual significance to the Aboriginal traditional owners of the land, and the reserve protects one of the oldest religious sites in the world as well as the natural rock formations found there. ''Karlu Karlu'' is the local Aboriginal term for both the rock features and the surrounding area. The Aboriginal term translates as "round boulders" and refers to the large boulders found mainly in the western side of the reserve. The English name for the boulders derives from a quote by John Ross during the 1870 Australian Overland Telegraph Line expedition, where he said "This is the Devil’s country; he’s even emptied his bag of marbles around the place!" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boulder Along The Chief Hike In Stawamus Chief Provincial Park, BC (DSCF7553)
In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than 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. The word ''boulder'' derives from ''boulder stone'', from the Middle English ''bulderston'' or Swedish ''bullersten''. Online Etymology Dictionary. Retrieved December 9, 2011, from Dictionary.com website. In places covered by s during s, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet. Earth is currently in the Quaternary glaciation. Individual pulses of cold climate within an ice age are termed '' glacial periods'' (or, alternatively, ''glacials, glaciations, glacial stages, stadials, stades'', or colloquially, ''ice ages''), and intermittent warm periods within an ice age are called '' interglacials'' or ''interstadials''. In glaciology, ''ice age'' implies the presence of extensive ice sheets in both northern and southern hemispheres. By this definition, Earth is currently in an interglacial period—the Holocene. The amount of anthropogenic greenhouse gases emitted into Earth's oceans and atmosphere is predicted to prevent the next glacial period for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horeke Basalts
The Horeke basalts is a disused formation that contained Miocene-Pliocene basalt lava flows that covered a large area in central Northland Region of New Zealand, and in places forms a high plateau around Okaihau. Wairere Boulders is a nature park providing walkways through boulders of basalt, derived by erosion of one of these older basalt flows that used to be included in the Horeke Basalt and are now included in the Kerikeri Volcanic Group. Origin The boulders in the Wairere valley are the erosional remnants of a lava flow out of a volcano near Lake Ōmāpere (near Kaikohe Kaikohe is the seat of the Far North District of New Zealand, situated on State Highway 12 about 260 km from Auckland. It is the largest inland town and highest community above sea level in the Northland Region. With a population of ove ...) that has been dated as approximately 2.8 million years old. There are two dates for these Horeke basalts: one at 2.84 and the other at 2.67 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobble (geology)
A cobble (sometimes a cobblestone) is a clast of rock defined on the Udden–Wentworth scale as having a particle size of , larger than a pebble and smaller than a boulder. Other scales define a cobble's size differently. A rock made predominantly of cobbles is termed a conglomerate. Cobblestone is a building material based on cobbles. Etymology Cobbles, also called cobblestones, derive their name from the word cob, meaning a rounded lump. The term is further related to the German ', meaning ''head''. Chester Wentworth referred to cobbles as ''cobble bowlders'' in his 1922 paper that would become the basis for the Udden–Wentworth scale. Classifications Within the widely used Krumbein phi scale of grain sizes, cobbles are defined as clasts of rock ranging from −6 to −8 φ. This classification corresponds with the Udden–Wentworth size scale which defines cobbles as clasts with diameters from . On this scale, cobbles are larger than pebbles which measure in diame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Baths
The Baths is a beach area on the island of Virgin Gorda among the British Virgin Islands in the Caribbean. Geography The Baths is situated about south off the maintown Spanish Town at the southern tip of the island between Spring Bay and Devil's Bay. The Baths is an area of unique geologic formations and one of the BVI's major tourist destinations. Area Although volcanism accounts for much of the Virgin Islands, The Baths was formed by granite that eroded into piles of boulders on the beach. Granite forms from the slow cooling of magma at depth nowhere close to surface volcanoes. The granite only appears at the surface after geologic ages have eroded away all the overburden covering it. Once exposed, erosion continued to isolate the granite into large boulders and round their surfaces. The boulders form natural tidal pools, tunnels, arches, and scenic grottoes that are open to the sea. The largest boulders are about long. Since 1990, the area has been a BVI National Park ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and waves; glacial plucking, abrasion, and scour; areal flooding; wind abrasion; groundwater processes; and mass movement processes in steep landscapes like landslides and debris flows. The rates at which such processes act control how fast a surface is eroded. Typically, physical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clastic Rock
Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus,Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-3 chunks, and smaller grains of rock broken off other rocks by physical weathering.Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-5 Geologists use the term clastic to refer to sedimentary rocks and particles in sediment transport, whether in suspension or as bed load, and in sediment deposits. Sedimentary clastic rocks Clastic sedimentary rocks are rocks composed predominantly of broken pieces or ''clasts'' of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on grain size, clast and cementing material (matrix) composition, and texture. The classification factors are often useful in determining a sample's environment of deposition. An example of clastic environment would be a river system in which the full range of grains being transported b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virgin Gorda
Virgin Gorda () is the third-largest island (after Tortola and Anegada) and second-most populous of the British Virgin Islands (BVI). Geography Located at about 18 degrees, 48 minutes North, and 64 degrees, 30 minutes West, it covers an area of about . The main commercial and residential area is Spanish Town on the southwestern part of the island. An unusual geologic formation known as " the Baths" located on the southern end of the island makes Virgin Gorda one of the BVI's major tourist destinations. At the Baths, in spite of evidence of the island's largely volcanic origins, huge granite boulders lie in piles on the beach, forming scenic grottoes that are open to the sea. Granite is an intrusive igneous rock, thus not volcanic. It did form from magma, however, at great depth. Granite becomes exposed at the Earth's surface only after geologic ages of erosion removes the overburden. At the surface, weathering has broken the granite into large boulders and rounded their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Bronze Horseman
The ''Bronze Horseman'' (russian: link=no, Медный всадник, literally " copper horseman") is an equestrian statue of Peter the Great in the Senate Square in Saint Petersburg, Russia. It was opened to the public on 7 (18) August 1782. Commissioned by Catherine the Great, it was created by the French sculptor Étienne Maurice Falconet. The name influenced a 1833 poem of the same name by Alexander Pushkin, which is widely considered one of the most significant works of Russian literature. The statue is now one of the symbols of Saint Petersburg. The statue's pedestal is the Thunder Stone, the largest stone ever moved by humans. The stone originally weighed about 1500 tonnes, but was carved down during transportation to its current size and weight of 1,250 tons. Statue The equestrian statue of Peter the Great is situated in the Senate Square (formerly the Decembrists Square), in Saint Petersburg. Catherine the Great, a German princess who married into the Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock (geology)
In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of magma in the asthenosphere. The study of rocks involves multiple subdisciplines of geology, including petrology and mineralogy. It may be limited to rocks found on Earth, or it may include planetary geology that studies the rocks of other celestial objects. Rocks are usually grouped into three main groups: igneous rocks, sedimentary rocks and metamorphic rocks. Igneous rocks are formed when magma cools in the Earth's crust, or lava cools on the ground surface or the seabed. Sedimentary rocks are formed by diagenesis and lithification of sediments, which in turn are formed by the weathering, transport, and deposition of exi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
