what is it called when decomposed rock covers a bedrock??
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Saprolite ? -- a soft, earthy, clay-rich thoroughly decomposed rock formed in place by chemical weathering of igneous or metamorphic rocks\n\nC-horizon (soils) ? -- partially disintegrated parent material and mineral particles are in this horizon. C horizons may also be called "parent material".\n\nOverburden ? - engineering term for anything not bedrock\n\nOh, yeah, generally decomposed rocks are called soils.  Maybe I'm being too specific.
391814
Plutonic rocks are those which have have solidified from magma while still underground. the significance of finding them at the surface is that their presence implies that the ground has been uplifted sufficiently for all the overlying rock to have been eroded.
581235
First, to all those who don't know what a dike is...\n\nA dike or dyke is an intrusive igneous body of rock.\n\nMagma will branch out from the magma chamber though breaks or fractures in the pre-existing rock layers. When it cools, intrusive igneous rocks form.\n\nDIKES, in particular, form when magma intrudes into existing rock strata or layers & then hardens. SILLS form in much the same way with one difference.\n\nDIKES cut across strata whereas SILLS form parallel to the rock layers.
276057
It's called the "Moho," which is short for "Mohorovicic Discontinuity."  It is named for the scientist who postulated its existence.  No one has ever drilled down far enough to see it, but that layer has certain unique physical properties.
808478
Whilst still below the surface it is called magma. Rocks which from from magma which has not been extruded at the surface cool more slowly (as they are at greater depth and hence higher temperatures) and thus have time to grow larger crystals before solidifying, producing a coarse-grained texture. These rocks are referred to as 'plutonic' and include gabbros, diorites, and good old granite. (You'll notice gabbros are darker due to their higher content of iron, etc - where as granites are a lighter colour as they are more rich in silica).\n\nLiquid rock at the surface is referred to as lava, and cools to form volcanic rocks such as basalts, andesites, and rhyolites (and obsidian, which is a really cool black volcanic glass). Due to cooling faster, volcanic rocks are quite fine-grained: if you look at a granite, you'll see indiviual crystals of the minerals (those little black or shiny silver-ish specks, or the large-ish pink or white crystals of feldspar) whereas to the naked eye, a volcanic rock such as basalt often looks rather like just a grey rock! (Looks pretty wicked under the polarizing microscope though...!)
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A rolling stone gathers no moss - should be 'bryophitic', I think.\n\n"Nomadic fragments of igneous and metamorphic strata, having non-zero quantities of angular momentum, accumulate no forms of bryophitic plant life"
261483
These are igneous rocks.
518090
What you are observing is the oxidation and weathering of a rock. The outside of the rock is exposed to the elements and gets bleached out, the inside is protected by the outer layers.
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Erosion breaks up igneous and metamorphic rocks, and the particles build up to create sedimentary rocks.  \n\nHope this is helpful.
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Two times of mines. Open pit or strip mining where the overburden (ground cover) is removed by large earth moving machines, e.g., giant drag lines, Once the coal seam is exposed, it is removed by blasting, and the use of large shovel and trucks.\nIn an underground mine, there are two basic types. First roof and pillar where the coal is removed by cutters and either loaded directly onto or trucked to conveyor belts to be brought to the surface. The pillars support the roof from collapsing but also represent coal that is left behind. The second is called long wall mining where a long (600")continous cutter removes the coal and loads it directly to a conveyor belt. The cutter is supported by a large hydraulic roof support system which protects the cutter as it moves forward. The roof of the seam is allowed to collapse behind the long wall miner.
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This is dependent on how much sediment is deposited on top of the bedrock.\n\nIn some places, the bedrock is exposed. In others, the bedrock is very deep.\n\nIn areas closer to the coast, termed "coastal plains", the bedrock is usually deeper than anywhere else. This is b/c of all the sediments deposited due to rises & falls of sea levels.\n\nAs you move closer to mountainous areas, the bedrock is relatively shallow.\n\nAs for your other question, it would depend on the type of bedrock as to whether it would be stable & sturdy enough to do what you are proposing.\n\nMetamorphic & igneous bedrock are stable. Some places like in Florida have sedimentary limestone bedrock. That would not be a good place for a "bomb shelter".
1119562
When you dig deep into the earth/mud, you will hit ROCK - that is Bedrock.
30785
Chemical erosion (also called weathering) occurs when rock or other materials are changed into smaller pieces by chemical processes.  These processes include direct oxidation (such as iron rusting), chemical dissolving (such as acid rain reacting with marble or limestone) and other chemical processes.  \nSome good site to look at are below:
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Through the processes of weathering, erosion, deposition, sedimentation, cementation, & lithification an igneous rock can become sedimentary.\n\nIgneous rock can be weathered by one of two processes. The first is mechanical weathering. This would include things like the freeze/thaw cycles. Water entering into tiny cracks in rock will freeze causing the crack to expand. There is a larger gap left when the ice melts. Some types of igneous rock will also exfoliate. As they emerge to the surface through uplifting, they will expand (due to less pressure). Sheets of rock will literally peel off from the rock's surface and fall at the base of the rock.\n\nThe other is chemical weathering. This is usually b/c of water's interaction w/ the minerals in the rock. One type of mineral will break down into another more stable one.\n\nThis weathered rock can erode & be transported elsewhere where it is deposited as sediment.\n\nMany layers of sediment may be placed down. Pressure from the layers above cause the water & air in the sediment layers below to be squeezed out.\n\nPressure from above, along w/ dissolved minerals left behind from the water, can cause lithification & cementation to occur.\n\nThese processes take quite some time to occur.
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rocks are made up of minerals
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Bedrock is defined as solid unweathered rock lying beneath surface deposits of soil.For a particular place all such rocks are called bedrock geology group. \n             The bedrock geology of Nigeria is composed of four main groups known as the Basement Complex, the Younger Granites, the Sedimentary Series and Tertiary to Recent Volcanic Rocks.\n       The Basement Complex\nThe Basement Complex of Nigeria occupies the western part of the Pan-African mobile belt, which lies between the West African and Congo Cratons.  It occupies about half the surface area of Nigeria. It is composed of five major rock assemblages:  \ni. The Migmatite-Gneiss Complex;     \nii.  The Schist Belts - composed of meta-sedimentary and meta-igneous rocks;     \niii. Granites and granite gneisses;     \niv. Charnockites, diorites and gabbros;   \nv.  Volcanics and hypabyssals.  \n    \nCommercial deposits of Gold associated with other metallic minerals occur within the Schist Belts of the Basement Complex. Tantalite, Columbite and Tin ore are associated with Pegmatites in the Older Granite suite. High quality gemstones and exotic granites also occur.\n\nThe Younger Granite\nThe younger granites form rugged hills of Jurassic age, and contain tinstone and columbite. Valuable deposits of these minerals have been formed from the disintegration by weathering of the granites. The concentration of these ore minerals is present in stream beds of earlier and recent geological epochs. Small quantities of wolframite also occur in certain Younger Granites, and some contain the potentially valuable radioactive mineral, pyrochlore.\n\nThe Sedimentary Series\nTechnically, the sedimentary basins can be divided into three groups:    \ni. Rift or Aulacogen Basins: These consist of the Benue, Bida and Anambra.  One of these basins (Benue) host commercial deposits of Lead/Zinc (with associated Germanium, Cadmium and Silver), Barites, Limestone and other minerals;     \nii. Marginal basins:  Niger Delta and southwestern (or Dahomey).  The Niger Delta basin is known for hydrocarbon production while the southwestern Basin has huge deposits of limestone and bitumen (tar-sand);     \niii. Intra Continental Basins: the Sokoto and Chad Basins which extend beyond the borders of the country.  The Sokoto Basin hosts large deposits of limestone and some phosphate/gypsum. The Chad Basin contains somel quantities of bentonitic clay, trona, gypsum and diatomite.\n \n  \nThe Tertiary - Recent Volcanic Rocks  \nVolcanic activity has taken place intermittently from tertiary to recent times. The most extensive outcrops are in the Biu and Longuda plateaux of north-eastern Nigeria and on the Jos Plateau. Scattered occurrence are found within the Benue Trough. The dominant rock is basalt with alkaline affinities. The basalt ranges from 22 million years to 7 million years in age.
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Sedimentary rock is one of the three main rock groups (along with igneous and metamorphic rocks) and is formed in three main ways—by the deposition of the weathered remains of other rocks (known as 'clastic' sedimentary rocks); by the deposition of the results of biogenic activity; and by precipitation from solution. Sedimentary rocks include common types such as chalk, limestone, sandstone, clay and shale. Sedimentary rocks cover 75% of the Earth's surface. Four basic processes are involved in the formation of a clastic sedimentary rock: weathering (erosion), transportation, deposition and compaction.\n\nSedimentary rocks are formed from overburden pressure as particles of sediment are deposited out of air, ice, or water flows carrying the particles in suspension. As sediment deposition builds up, the overburden (or lithostatic) pressure squeezes the sediment into layered solids in a process known as lithification ("rock formation") and the original connate fluids are expelled. The term diagenesis is used to describe all the chemical, physical, and biological changes undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface weathering.\n\nSedimentary rocks contain important information about the history of the Earth. They contain fossils, the preserved remains of ancient plants and animals. The composition of sediments provides us with clues as to the original rock. Differences between successive layers indicate changes to the environment which have occurred over time. Sedimentary rocks can contain fossils because, unlike most igneous and metamorphic rocks, they form at temperatures and pressures that do not destroy fossil remnants.\n\nThe sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only five percent of the total. As such, the sedimentary sequences we see represent only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. These rocks are very useful for building and architecture.\n\nYou can get more information at following link\n\nhttp://en.wikipedia.org/wiki/Sedimentary_rock