The geosphere is the Earth itself, the rocks, minerals, and landforms of the surface as well as its interior. |
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Until recently, the geosphere was studied primarily by mapping rocks, fossils and soils as they vary across the landscape. |
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Because of friction and the rigidity of rocks, they cannot glide or flow past each other easily, and occasionally all movement stops. |
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Downland is formed when chalk formations are raised above the surrounding rocks. |
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They breed in large colonies on coastal cliffs or offshore islands, nesting in crevices among rocks or in burrows in the soil. |
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During the winter months grey seals can be seen hauled out on rocks, islands, and shoals not far from shore, occasionally coming ashore to rest. |
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Most eels live in the shallow waters of the ocean and burrow into sand, mud, or amongst rocks. |
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They are usually picked off the rocks by hand or caught in a drag from a boat. |
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Beyond the bay the underlying rocks emerge from the sand to form the promontory of Porthcawl Point. |
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Formulations were later developed based on kaolin with quartz, feldspars, nepheline syenite or other feldspathic rocks. |
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It is smooth in texture and forms delicate, sheetlike thalli, often clinging to rocks. |
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Uranium is a very heavy metal that is abundant on Earth and is found in sea water as well as most rocks. |
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In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger. |
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At their mouths there are typically rocks, bars or sills of glacial deposits, which have the effects of modifying the estuarine circulation. |
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The erosive force of the ice moved across the land, removing the soft sandstone and leaving behind the harder rocks. |
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The minerals and metals found in rocks have been essential to human civilization. |
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The scientific study of rocks is called petrology, which is an essential component of geology. |
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The proportion of silica in rocks and minerals is a major factor in determining their name and properties. |
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These physical properties are the end result of the processes that formed the rocks. |
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Over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. |
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Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earth's crust. |
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Over 700 types of igneous rocks have been described, most of them having formed beneath the surface of Earth's crust. |
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This is termed burial metamorphism, and it can result in rocks such as jade. |
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Depending on the structure, metamorphic rocks are divided into two general categories. |
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Schists are foliated rocks that are primarily composed of lamellar minerals such as micas. |
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The use of rocks has had a huge impact on the cultural and technological development of the human race. |
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Boulder sized clasts are found in some sedimentary rocks, such as coarse conglomerate and boulder clay. |
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Large gravel deposits are a common geological feature, being formed as a result of the weathering and erosion of rocks. |
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Because they evolved rapidly, they aid geologists in dating the surrounding rocks. |
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Scallops can be found living within, upon, or under either rocks, coral, rubble, sea grass, kelp, sand, or mud. |
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Female Branchiura do not carry eggs in external ovisacs but attach them in rows to rocks and other objects. |
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They choose beaches with soft sand because their softer shells and plastrons are easily damaged by hard rocks. |
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This can help with camouflage when the cuttlefish becomes visually similar to objects in its environment such as kelp or rocks. |
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The decay of the radionuclides in rocks of the Earth's mantle and crust contribute significantly to Earth's internal heat budget. |
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Oil reserves in sedimentary rocks are the source of hydrocarbons for the energy, transport and petrochemical industries. |
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Evaporites are considered sedimentary rocks and are formed by chemical sediments. |
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The abundance of rocks formed by seawater precipitation is in the same order as the precipitation given above. |
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Hard rocks such as limestone, sand, gravel, and slate are generally quarried into a series of benches. |
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Carboniferous rocks in Europe and eastern North America largely consist of a repeated sequence of limestone, sandstone, shale and coal beds. |
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The rocks formed at that time were stained red by iron oxides, the result of intense heating by the sun of a surface devoid of vegetation cover. |
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The top of the Coal Measures may be marked by an unconformity, the overlying rocks being Permian or later in age. |
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Volcanic eruptions also provide the benefit of adding nutrients to soil through the weathering process of volcanic rocks. |
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In places the intrusions, indeed, outbulk the rocks among which they have been thrust. |
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Because of the relatively young age and great thickness of the system, Cretaceous rocks are evident in many areas worldwide. |
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This is a list of islands, islets, and rocks that surround the island of Crete. |
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This accounts for the great age of the rocks comprising the continental cratons. |
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Another subtype is an island or bar formed by deposition of tiny rocks where water current loses some of its carrying capacity. |
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Paralell with volcanism a hilly peneplain formed in northeastern Scania due to weathering and erosion of the basement rocks. |
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These thick deposits accumulated as earlier Silurian rocks, uplifted by the formation of Pangaea, eroded and then deposited into river deltas. |
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They fought over her by throwing large rocks at each other, one of which became Muckle Flugga. |
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At the top of this area, patches of dark lichens can appear as crusts on rocks. |
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The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all active rift systems. |
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The sedimentary rocks associated with continental rifts host important deposits of both minerals and hydrocarbons. |
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Within the scope of this topic, uplift relates to denudation in that denudation brings buried rocks closer to the surface. |
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Similar Phanerozoic rocks also cover the Baltic republics, Poland and northern Germany. |
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Most soil consists of moraine, a grayish yellow mixture of sand and rocks, with a thin layer of humus on top. |
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Greece and the Levant also retain many units of limestone and other sedimentary rocks deposited by various stands of the Tethys Ocean. |
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It was introduced by Jules Desnoyers in 1829 for sediments of France's Seine Basin that seemed clearly to be younger than Tertiary Period rocks. |
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They can also be made into clam chowder or they can be cooked using hot rocks and seaweed in a New England clam bake. |
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Food is also obtained by searching the ground, often on the shore among sand, mud or rocks. |
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Detailed geological investigation showed that it was the result of delayed compactional diagenesis of the Chalk Formation reservoir rocks. |
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The restoration was complicated by the presence of old seawalls, groins, piles of rocks and other structures. |
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Amber is globally distributed, mainly in rocks of Cretaceous age or younger. |
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Paul put the skull back in its proper place, put back the coffin lid, and kicked dirt and rocks overtop. |
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Random polarization returns usually indicate a fractal surface, such as rocks or soil, and are used by navigation radars. |
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There are three main beaches in the villages, which are separated by areas of rocks with interesting rockpools. |
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A swimming beach known as Sandways lies a short walk out of the village across the rocks towards Fort Picklecombe. |
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Studies of glacial rebound give us information about the flow law of mantle rocks and also past ice sheet history. |
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Ice, water and mantle rocks have mass, and as they move around, they exert a gravitational pull on other masses towards them. |
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For instance, parts of Scotland and Ireland contain rocks very similar to those found in Newfoundland and New Brunswick. |
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Older inactive orogenies, such as the Algoman, Penokean and Antler, are represented by deformed rocks and sedimentary basins further inland. |
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His theory essentially held that mountains were created by the squeezing of certain rocks. |
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Magma that reaches the surface to become lava cools rapidly, resulting in rocks with small crystals such as basalt. |
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Existing rocks that come into contact with magma may be melted and assimilated into the magma. |
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The Lewisian consists mainly of granitic gneisses with a minor amount of supracrustal rocks. |
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Supracrustal rocks of the Loch Maree Group form two large areas of outcrop near Loch Maree and Gairloch in the Southern Region. |
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The relationship between the supreacrustal rocks and the Scourian gneisses remains unclear. |
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These igneous rocks are intruded into the Leverburgh and Langevat supracrustals. |
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These two belts of metasediments flank the South Harris igneous complex, and form the largest outcrop of such rocks in the Outer Hebrides. |
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Radiometric dating has shown these metasediments to be of Paleoproterozoic age, similar to the rocks of the Loch Maree Group. |
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Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. |
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Sedimentary rocks are deposited in layers as strata, forming a structure called bedding. |
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Sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores. |
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The scientific discipline that studies the properties and origin of sedimentary rocks is called sedimentology. |
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Clastic sedimentary rocks are composed of other rock fragments that were cemented by silicate minerals. |
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Clastic sedimentary rocks, are subdivided according to the dominant particle size. |
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Biochemical sedimentary rocks are created when organisms use materials dissolved in air or water to build their tissue. |
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Sedimentary rocks are formed when sediment is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension. |
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However, some sedimentary rocks, such as evaporites, are composed of material that form at the place of deposition. |
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Sedimentary rocks are often saturated with seawater or groundwater, in which minerals can dissolve, or from which minerals can precipitate. |
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Burial of rocks due to ongoing sedimentation leads to increased pressure and temperature, which stimulates certain chemical reactions. |
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Thick sequences of red sedimentary rocks formed in arid climates are called red beds. |
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In contrast to igneous and metamorphic rocks, a sedimentary rock usually contains very few different major minerals. |
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Carbonate rocks dominantly consist of carbonate minerals such as calcite, aragonite or dolomite. |
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In most sedimentary rocks, mica, feldspar and less stable minerals have been reduced to clay minerals like kaolinite, illite or smectite. |
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Unlike most igneous and metamorphic rocks, sedimentary rocks form at temperatures and pressures that do not destroy fossil remnants. |
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The sequence of beds that characterizes sedimentary rocks is called bedding. |
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When sedimentary rocks have no lamination at all, their structural character is called massive bedding. |
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An example of a diagenetic structure common in carbonate rocks is a stylolite. |
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Especially in warm climates, shallow marine environments far offshore mainly see deposition of carbonate rocks. |
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The facies of all rocks of a certain age can be plotted on a map to give an overview of the palaeogeography. |
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Sedimentary rocks contain important information about the history of the Earth. |
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The sea breaks upon this coast against a palisadoed fence of rocks and cliffs, around which swarm flocks of polar birds with cries and screams. |
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In this mode, the posteriorly moving waves push against contact points in the environment, such as rocks, twigs, irregularities in the soil, etc. |
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These reptiles are mostly active during the twilight and occasionally bask in the sun, but are more often found hiding beneath rocks and logs. |
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Species such as Angraecum sororium are lithophytes, growing on rocks or very rocky soil. |
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They are able to grow on inhospitable surfaces, including bare soil, rocks, tree bark, wood, shells, barnacles and leaves. |
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The continental crust consists of lower density material such as the igneous rocks granite and andesite. |
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Most of this salt was released from volcanic activity or extracted from cool igneous rocks. |
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Groundwater is present in most rocks, and the pressure of this groundwater affects patterns of faulting. |
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Deposition of transported sediment forms many types of sedimentary rocks, which make up the geologic record of Earth history. |
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The most common rocks in West Antarctica are andesite and rhyolite volcanics formed during the Jurassic period. |
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Most of the rocks forming the surface of the present High Atlas were deposited under the ocean at that time. |
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The rocks that form Cape Agulhas belong to the Table Mountain Group, often loosely termed the Table Mountain sandstone. |
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The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis. |
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Because of this, rocks closest to a boundary are younger than rocks further away on the same plate. |
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Chemically, mafic rocks are on the other side of the rock spectrum from the felsic rocks. |
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Older rocks will be found farther away from the spreading zone while younger rocks will be found nearer to the spreading zone. |
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The transitional crust of volcanic margins is composed of basaltic igneous rocks, including lava flows, sills, dykes, and gabbro. |
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Ancient examples have been found in rocks dating back to the Neoproterozoic. |
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The plants grow subtidally and attach to coral, rocks or shells in moderately exposed or sheltered rocky or pebble areas. |
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Reversals also provide the basis for magnetostratigraphy, a way of dating rocks and sediments. |
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In contrast, a dike is a discordant intrusive sheet, which does cut across older rocks. |
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Some plutonic rocks related to the traps escaped crustal contamination reflecting more directly the source of the magmas in the mantle. |
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These rocks can preserve a record of the field if it is not later erased by chemical, physical or biological change. |
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The Cape granites were emplaced and the Kaaimans Group rocks were folded and thermally metamorphosed during this period. |
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The mountains of the Cape Fold Belt are composed of rocks belonging to the Cape Supergroup, which is more extensive than the Fold Belt. |
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These diamictite rocks are composed of finely ground mud, containing a jumble of faceted pebbles. |
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Almost all of these ranges consist of hard erosion resistant Peninsula Group rocks. |
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They may establish sites where rocks or similar items are available as natural anvils on which the animals habitually break open the shells. |
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Octopus middens are commonly made of rocks, shells, and the bones of prey, although they may contain anything the octopus finds that it can move. |
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The coast between Cabo Falso Bojador and Cabo Bojador, 10 miles SW, consists of a sandy beach fringed by rocks. |
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They also use their mouths to dig into sand to form their shelters under big rocks, jetting it out through their gills. |
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Prehistoric music is inferred from found instruments, while parietal art can be found on rocks of any kind. |
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Granite is one of the rocks most prized by climbers, for its steepness, soundness, crack systems, and friction. |
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Over time the slate and sandstone rocks covering the granite were eroded exposing the granite in areas such as Dartmoor and Bodmin Moor. |
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It appears to have been intruded along the interface between Devonian and Carboniferous rocks. |
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Around the edges of many of the plutons the country rocks have been transformed by heat in a process known as contact metamorphism. |
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The effect of this process depends on the type of rocks which were heated and their distance from the intrusion. |
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Fine grained sedimentary rocks were transformed into hornfels and minerals such as amphibole, pyroxene. |
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At greater distances from the plutons, the only evidence of metamorphism is spotting in these rocks. |
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The mineral deposits are associated with multiple lodes and fractures that dip steeply and cut across both the granites and the country rocks. |
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In the north and centre of the county the substrate is the rocks of the Chalk Group, which form the Hampshire Downs and the South Downs. |
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However, this is difficult for some time periods, because of the problems involved in matching rocks of the same age across continents. |
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Pseudofossils are visual patterns in rocks that are produced by geologic processes rather than biologic processes. |
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In the mountains of Parma and Piacenza multitudes of shells and corals with holes may be seen still sticking to the rocks. |
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He observed that rocks from distant locations could be correlated based on the fossils they contained. |
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For the first 150 years of geology, biostratigraphy and superposition were the only means for determining the relative age of rocks. |
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It was built too far into the sea and constantly suffered erosion, until now reduced to a pile of rocks. |
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Where the land rises to the sea there are several parallel strata of Jurassic rocks, including Portland limestone and the Purbeck beds. |
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The rocks can be viewed from the Dorset section of the South West Coast Path. |
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Some people desire to preserve the rocks and protect them from the erosive processes that formed Old Harry. |
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Due to geological folding of the Alpine orogeny, the strata in the main section of the Bay are vertical, with younger rocks to the north. |
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The radula primarily functions to scrape bacteria and algae off rocks, and is associated with the odontophore, a cartilaginous supporting organ. |
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Alpine plants that cannot establish themselves in earthy gorges, must adapt to a petricolous habit in cracks in rocks. |
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In an abrasion process, debris in the basal ice scrapes along the bed, polishing and gouging the underlying rocks, similar to sandpaper on wood. |
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The eastern edge of the bay is formed from soft red and orange cretaceous rocks that are rapidly eroding. |
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Interactions between the chalk downs and softer undercliff rocks drive the geological changes affecting Ventnor. |
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Pliocene marine rocks are well exposed in the Mediterranean, India, and China. |
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Petroforms, or patterns and shapes made by many large rocks and boulders over the ground, are also quite different. |
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It uses evidence from ice sheets, tree rings, sediments, coral, and rocks to determine the past state of the climate. |
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The number includes islands, islets, and rocks of all sizes, including ones emerging at ebb tide only. |
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Hearthstone, the older brother, was distracted and playing with rocks when a Brunnmigi emerged from a well and killed Andiron. |
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Unfortunately, this was not a reliable method, and many an India ship ended up crashing on those rocks. |
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Ships, docks, and shipyards were destroyed and ports sabotaged with rocks and pine stakes. |
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Avoid iron rich deposits when using a compass, for example, certain rocks which contain magnetic minerals, like Magnetite. |
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In 1864, the Governor of the Bahamas reported that there were 29 islands, 661 cays, and 2,387 rocks in the colony. |
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I never imagined seeing something so wild and desolate as those emerging dark rocks in the middle of the raging waves. |
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Metamorphic rocks of slate, schist and arkose dominate the northern part of the island. |
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Granite and serpentine rocks predominate, but the shores of Amboina Bay are of chalk and contain stalactite caves. |
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In every area of the country the rocks which formed can be seen as a result. |
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The car was bombarded by rocks as it drove away from the angry crowd. |
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Centuries of erosion by wind have carved grooves in the rocks. |
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The gleam of the land is in its rocks, the fine-grained argillaceous rocks, here, not purple or grey, but green of living stone. |
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Bears coming out of holes in the rocks at the last moment, when the beat is close to them. |
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Tis like the bursting of the desert stream When to the field, with sultry drought bescorch'd, Between its echoing rocks it rolls its way. |
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Grapes grow on the brant rocks so wonderfully that ye will marvel how any man dare climb up to them. |
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A cannonproof breastwork, built during the previous war, extended along the beach from the hills to the rocks. |
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If you are surfing a wave through the rocks, make sure you have a clear route before catching the wave. |
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You think we don't know what you're doing, chooch? Throwing rocks at a scout convoy? |
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Little has been recorded on the biology of dascillids. Larvae of Dascillus are found in moist soil or under rocks. |
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As a result of decompaction, the permeability of low-porosity rocks may increase by several orders of magnitude. |
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We can only agree with Mermin's anonymous physicist, but must add that they are double-plus-good rocks, full of promise. |
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I'm just a plain hillbilly from East Jesus Nowhere with this adopted child that everybody keeps on telling me is dumb as a box of rocks. |
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Violetta is well aware of all this and goes out of her way to charm him.... He eats out of her hand and would not notice if she fed him rocks. |
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Assiduoud field-workers have discovered little pods of a rock called eclogite in the rocks around San Bernardino. |
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The Heath itself when they came to it was a white wilderness within the embracement of black rocks and mountains. |
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Epidote is found in greenstone belts and many metamorphic rocks such as gneiss and schist, and is hence fairly widespread. |
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I could hear the fragments from the flak shells hitting the plane like someone throwing rocks at it. |
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In sedimentary rocks, the magnetic foliation results from a combination of depositional processes and diagenetic compaction. |
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The fontinal cliff vegetation occupies moist rocky banks, damp ledges, and dripping rocks. |
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Of the high-silica, coarse-grained, quartz-rich igneous rocks, granodiorites are quantitatively the most important. |
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This part of Scotland largely comprises ancient rocks from the Cambrian and Precambrian, which were uplifted during the later Caledonian Orogeny. |
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The masons used rubble from their trimming of the face rocks as some of the hearting for the wall. |
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Early Namurian basinal mudstones are the source rocks for these hydrocarbons. |
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The most likely hydrocarbon source rocks are Early Jurassic marine mudstones. |
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South of the gneisses are a complex mixture of rocks forming the North West Highlands and Grampian Highlands in Scotland. |
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All the rocks found on the island are sedimentary, such as limestones, mudstones and sandstones. |
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Together they comprise the Skiddaw Group and include the rocks traditionally known as the Skiddaw Slates. |
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These pyroclastic rocks give rise to the craggy landscapes typical of the central fells. |
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The Iberian Peninsula contains rocks of every geological period from the Ediacaran to the Recent, and almost every kind of rock is represented. |
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They slew 7,000 Irish but, as the knights tried to move the rocks with ropes and force, they failed. |
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The frog is the foundation of the plow bottom, it takes the shock loads resulting from hitting rocks, and therefore, should be tough and strong. |
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Impactite is the term used for all rocks produced or affected by a hypervelocity impact event. |
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At daybreak on 21 July the English fleet engaged the Armada off Plymouth near the Eddystone rocks. |
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Can you help Uncle Pete find a way through the jaggedy rocks to the island? |
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The oldest rocks in the group are in the north west of Scotland, Ireland and North Wales and are 2,700 million years old. |
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His body sprouts fingers thicker than carrots. They grip me knobbily. He rocks back and forth like a leaky old boat shakes on the ocean. |
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The oldest rocks are exposed in the north, in areas such as the Kisatchie National Forest. |
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The oldest rocks date back to the early Tertiary Era, some 60 million years ago. |
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In between the Tertiary rocks of the north, and the relatively new sediments along the coast, is a vast belt known as the Pleistocene Terraces. |
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The variety of rocks of similar ages seen here have led to the county's name being lent to that of the Devonian period. |
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Limestone is less resistant than most igneous rocks, but more resistant than most other sedimentary rocks. |
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Two major classification schemes, the Folk and the Dunham, are used for identifying limestone and carbonate rocks. |
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Dunham divides the rocks into four main groups based on relative proportions of coarser clastic particles. |
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It is therefore usually associated with hills and downland, and occurs in regions with other sedimentary rocks, typically clays. |
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Karst topography and caves develop in limestone rocks due to their solubility in dilute acidic groundwater. |
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Karst topography is a landscape formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. |
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Interstratal karst is a karstic landscape which is developed beneath a cover of insoluble rocks. |
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The Peak District is formed almost exclusively from sedimentary rocks dating from the Carboniferous period. |
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In addition there are infrequent outcrops of igneous rocks including lavas, tuffs and volcanic vent agglomerates. |
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At the end of this period, the Earth's crust sank here which led to the area being covered by sea, depositing a variety of new rocks. |
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You enterprised a railroad through the valley, you blasted its rocks away, heaped thousands of tons of shale into its lovely stream. |
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Exmoor is an upland area formed almost exclusively from sedimentary rocks dating from the Devonian and early Carboniferous periods. |
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The name of the geological period and system, 'Devonian', comes from Devon, as rocks of that age were first studied and described here. |
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Towards the end of this period granite was formed beneath the overlying rocks of Devon and Cornwall, now exposed at Dartmoor and Bodmin Moor. |
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Between 63 and 52 Ma, the last volcanic rocks in Great Britain were formed. |
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In fact, it seems that in the Primary rocks the distinctive Leptosporangiate annulus was at least rare, if it existed at all. |
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The longue duree of river and rocks throws into relief the trivial pursuits of the dying man whose last thoughts are of a briefer time span. |
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Luca is now usually placed deep underground, in a fissure in hot igneous rocks, where she fed on sulphur, iron, hydrogen and carbon. |
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The coastline is composed mainly of resistant rocks that give rise in many places to impressive cliffs. |
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The north east of Cornwall lies on Carboniferous rocks known as the Culm Measures. |
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Shropshire has a huge range of different types of rocks, stretching from the Precambrian until the Holocene. |
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Shropshire has a number of areas with Silurian and Ordivician rocks, where a number of shells, corals and trilobites can be found. |
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As a whole, rocks of this type are referred to as mafic, because of the importance of magnesium and iron in their composition. |
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In Devon, near Challacombe, a group of rocks are named for the pixies said to dwell there. |
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Natural features seen on this stretch of coast include arches, pinnacles and stack rocks. |
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The oldest rocks exposed at the centre of the anticline are correlated with the Purbeck Beds of the Upper Jurassic. |
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The rocks of the central part of the anticline include hard sandstones, and these form hills now called the High Weald. |
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Otherwise the Low Weald retains its historic settlement pattern, where the villages and small towns occupy harder outcrops of rocks. |
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Granitic rocks are microcracked by differential contraction during cooling of the magma. |
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Sometimes we had to stop in midstream and midstorm because the sheets of rain made the passages between rocks invisible. |
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The classic Triassic marl, sand and conglomerate rocks are used predominantly throughout Cardiff as building materials. |
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Many of these Triassic rocks have a purple complexion, especially the coastal marl found near Penarth. |
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The overlying rocks of the Torridonian sandstone form mountains in the Torridon Hills such as Liathach and Beinn Eighe in Wester Ross. |
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The oldest rocks of Scotland are the Lewisian gneisses, which were formed in the Precambrian period, up to 3 billion years ago. |
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Silurian rocks form the Southern Uplands of Scotland, which was pushed up from the seabed during the collision. |
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Middle Devonian basaltic volcanic rocks are found on western Hoy, on Deerness in eastern Mainland and on Shapinsay. |
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A fault in ductile rocks can also release instantaneously when the strain rate is too great. |
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Fault rocks are classified by their textures and the implied mechanism of deformation. |
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Sedimentary rocks dominate the southern half of the island, especially Old and New Red Sandstone. |
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The path is regularly maintained but running water, uneven rocks and loose scree make it hazardous and slippery in places. |
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The rocks which today make up Snowdon and its neighbouring mountains were formed in the Ordovician Period. |
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These Precambrian rocks are schists and phyllites, often much contorted and disturbed. |
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Different regions contain rocks belonging to different geologic periods, dating as far back almost 2 billion years. |
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In the east of the city, in Craigie and Broughty Ferry, the bedrock geology is of extrusive rocks, including mafic lava and tuff. |
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Almost every day someone will go fishing, whether it is from the rocks, from a longboat or diving with a spear gun. |
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Using an early theory of inertia, Galileo could explain why rocks dropped from a tower fall straight down even if the earth rotates. |
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In sedimentary rocks with a significant water content, fluid at fracture tip will be steam. |
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Most of the islands have a bedrock formed from ancient metamorphic rocks and the climate is mild and oceanic. |
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These are amongst the oldest rocks in Europe, having been formed in the Precambrian period up to three billion years ago. |
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The granite here is anorthosite, and is similar in composition to rocks found in the mountains of the Moon. |
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Best in evidence where in contact with folded Cretaceous rocks which are uplifted by the Cenozoic granite. |
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Sculptors sometimes use found objects, and Chinese scholar's rocks have been appreciated for many centuries. |
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She incorporated stones and rocks which had been thrown through her window in a mixed media piece in her 2005 show. |
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Hull damage can be caused by submerged logs, poor strapping to trailers, and collisions with other boats, docks, rocks, etc. |
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The island itself is one of the wildest in the world on account of the bold and craggy rocks. |
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Quartz is a defining constituent of granite and other felsic igneous rocks. |
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It is a common constituent of schist, gneiss, quartzite and other metamorphic rocks. |
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Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides. |
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The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. |
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Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. |
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Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses. |
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The mineral grains in such rocks can generally be identified with the naked eye. |
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When the magma solidifies within the earth's crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, or diorite. |
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The central cores of major mountain ranges consist of intrusive igneous rocks, usually granite. |
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Hypabyssal rocks are less common than plutonic or volcanic rocks and often form dikes, sills, laccoliths, lopoliths, or phacoliths. |
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Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks. |
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Igneous rocks are classified according to mode of occurrence, texture, mineralogy, chemical composition, and the geometry of the igneous body. |
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All other minerals present are regarded as nonessential in almost all igneous rocks and are called accessory minerals. |
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Types of igneous rocks with other essential minerals are very rare, and these rare rocks include those with essential carbonates. |
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Plutonic rocks also tend to be less texturally varied and less prone to gaining structural fabrics. |
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Mineralogical classification is most often used to classify plutonic rocks. |
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Igneous rocks can be classified according to chemical or mineralogical parameters. |
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For volcanic rocks, mineralogy is important in classifying and naming lavas. |
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The following table is a simple subdivision of igneous rocks according to both their composition and mode of occurrence. |
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For instance, magmas commonly interact with rocks they intrude, both by melting those rocks and by reacting with them. |
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These are the elements that combine to form the silicate minerals, which account for over ninety percent of all igneous rocks. |
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The chemistry of igneous rocks is expressed differently for major and minor elements and for trace elements. |
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The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. |
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Many fossils are found within the rocks, including early fishes, arthropods and plants. |
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If the young birds leave the nest in bad weather they can be mortally wounded as they can be blown against the rocks. |
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Territorial marking consists of urinating on trees, vegetation and rocks, and depositing faeces in conspicuous places. |
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Changes in sea levels and climate led to a strong erosion and to the formation of more sedimentary rocks. |
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Most of these birds breed on isolated islands and rocks and thus are hard to observe. |
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Upon coming ashore, Andrew struck the rocks with his staff at which point a spring of healing waters gushed forth. |
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An end is complete when all eight rocks from each team have been delivered, a total of sixteen stones. |
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The carboniferous rocks of the Yorkshire coalfield further east have produced a rolling landscape with hills, escarpments and broad valleys. |
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The rocks formed during a period belong to a stratigraphic unit called a system. |
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As on Earth, many glaciers are covered with a layer of rocks which insulates the ice. |
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