Why sedimentary rocks are found as a veneer covering large areas of the igneous rock?
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There are many different sedimentary rocks but only three basic causes.\n\nFirst is where rock is weathered out and is washed down into valleys and rivers where it forms a mud and is then pressured to turn into rock.\n\nThe other is the sea floor where the same silt settles and becomes a thick layer over the years.  Then either the sea recedes or the land is thrust up leaving the mud high and dry as sedimentary rock.\n\nLastly we have limestone and chalk where sea creatures die, sink to the ocean floor and accumulate.  This then follows the same upthrust or ebb of the sea and is exposed as rock on the mainland.
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because Quartz (SiO) is very stable and resistant. Acid igenous rocks contain lots of quartz and thats what continents are basically ade of. These weather to produce sandstones, a very common form of sedimentary rock
129822
You've been given exhaustive lists, copied directly from websites without giving proper citation I imagine. \n\nHere is how to think about this question so that you can recall and understand the answer, without just memorizing a bunch of rock names.\n\nUse the rock cycle. Igneous rocks are of two groups, those formed within the earth and those formed by volcanism.  The volcanic rocks will show signs of that volcanism and will be things like black columnar basalt found in massive flows. Obsidian (volcanic glass) that flowed as liquid, scoria and pumice which are like foam because the dissolved gases expanded and made them bubble as they hardened. The other igneous group formed under the earth's surface, and includes things like granite where you can see the crystals that formed as it cooled and solidified. \n\nSedimentary rocks are also in two major informal groups (and a minor third). The first group of sedimentary rocks is clastics. These are formed by weathering, transport and deposition. Weatherings breaks down rocks like igneous, metamorphic and even sedimentary rocks and transport by wind, water, or gravity deposits these rocks as accumulations of clasts, (thus clastics). They become sandstone, shale, and conglomerate. The other major sedimentary group is carbonates. These rocks are 'born' because they are formed by living things. Ocean environments (and lakes too) have many organisms that make shells, corals that make reefs, and algae that make fine carbonate sediments (known as carbonate mud). Even bacteria get into the act helping to precipitate carbonates in many ocean environments. The third group of sedimentary rocks is those that are dissolved by water and deposited by evaporation or precipitation. These include gypsum, halite, sylvite, and many more. \n\nMetamorphic rocks all start life as one of the previous groups. You can metamorphose a granite into a granitic gneiss by burial, pressure and heat. You can metamorphose a basalt into an amphibolite. You can make limestone into marble. Sandstone turns into quartzite.\n\nRemember the rock cycle, associate the rocks as they move through it, and you won't have trouble remembering examples of rock types. Also don’t get tripped up by the difference between a mineral and a rock. Geologists sometimes use the two terms identically, but there is a formal difference between a rock (which is an impure mixture) and a mineral that is chemically consistent.
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It is trees or wood that has been buried and due to the time and the type of enviornment that it was in, the wood was replaced by quartz minerals mimicing the wood grains and structure.  It is a case of mineral repalcement
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Applications of the concept that the present is the key to the past in the earth's history:\n1. volcanology: Today, volcanic rocks are generated at active volcanic centers--from the cooling of lava. We assume that when we map out similar rocks in older strata that they also formed at volcanic centers--even if there is no active volcanism in the area today. \n2. paleontology and paleoenvironment: We know that certain plants and animals live in the ocean and certain organisms live on land.  If we find fossils of marine organisms(like oysters, corals, ammonoids, shark teeth) in sedimentary rocks on high mountains, we interpret that the strata were originally deposited on the sea bottom that has since been uplifted.\n3. paleoenvironment: we know that modern desert areas covered by dunes have certain characteristics--that the dunes have certain types of crossbeds, the sand is well-sorted and well-rounded, for example. If we observe similar characteristics in sandstone beds of the Colorado Plateau, for example, that is considered evidence for an arid desert environment in the past.\n4. Modern plate boundaries are associated with major fault systems, certain rocks types, etc. In  the Sierra Nevada, geologists have mapped out ancient fault boundaries that put marine sedimentary rocks against dissimilar volcanic arc-related rocks. The patterns they have mapped out are considered evidence that the plate boundary of North America was once a convergent margin located farther east than it is today.
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dairydahm is right!  It's conglomerate.  Sedimentary (so you were right, too) rocks can contain pebbles of similar or varying sizes, depending where it formed.  Below are some sites that have pics of conglomerates for you to check--if you don't believe us.  (I'm a geology teacher, by the way.  (-; )
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Volcanoes are one of the main ways that igneous rocks are deposited on the surface of the earth. Other igneous rocks form by cooling of magma within the earth and do not reach the surface. These are called intrusive igneous rocks. \n\nOne of the models to explain how our atmosphere was created suggests that volcanic activity released both water vapor and other gases. The present day atmosphere has changed its composition from the original because of the plants that have released oxygen from carbon dioxide.  Current estimates are that volcanic gases contribute 110 million tons of carbon dioxide per year while man's contribution is about 10 billion tons a year. \n\nVolcanoes also contribute other gases and airborne particulates to the atmosphere that can have adverse affects on the environment for several years after a major eruption. Sulphur dioxide is present in most volcanic eruptions and this changes to acid rain as it is dissolved in the atmosphere. This is very harmful to plant life and damages healthy soil. Volcanic ash is often ejected high into the atmosphere and remains there for many years before settling back to earth. This has been speculated to have been the cause of global periods of colder weather  that occured in the 400's and in prior times. \n\nThe formation of intrusive igneous rocks also involves this outgassing of carbon dioxide and other gases, but because it takes place very slowly and often deep underground it has a very gradual effect on the atmosphere. Much of the gas that comes from these rocks will stay traped by being dissolved in water that remains in the subsurface. The movement of this water actually is responsible for many mineral deposits of things like copper ore.
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I think you mean rock fragments. If yes,\n\nRock fragments are further eroded by forces of nature: wind or water. depending on the level of disintegration, it forms various kinds of soil or sand.\n\nSometimes if fragments get buried under several layers of soil, fragments clump together to form sedimentary rocks\n\nHope that helps\n\nR
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Identification of a sedimentary facies (or any rock facies, for that matter) requires an intimate knowledge of the type locality of that particular facies, what major minerals constitute the lithogenics, and what the depositional/erosional/tectonic activity of the region was like since the formation of the facies.  \n\nFor example, when I was out west I was able to trace the Navajo sandstone throughout the four corners region, from the Grand Canyon all the way up through Utah.  There were points where the Navajo was the thickest facies, while in other regions the Navajo was very thin and nearly unnoticeable.  In those thin regions, the deposition of the Navajo might not have been as pronounced (sedimentary facies are formed by deposition of sediment), or the facies could have been exposed at the surface much longer than in other regions and subsequently eroded away.  You can determine if this happened by looking for unconformities between the Navajo and the facies above it.  \n\nHowever, there are certain characteristics of the Navajo (Aeolian remnants, highly silicic, slight oxidation) that make it the Navajo formation.  Despite the varying thickness of the facies, you can trace these rock characteristics throughout the American Southwest.  So yes, if a geologist wishes to determine the full extent of a lithogenic facies, they must attempt to trace that facies as far out as they possibly can, which means a lot of survey work.\n\nWhat most geologists do nowadays is check the state geological maps of the regions they're interested in and look for rock facies that match the facies of the rock they're studying.  Oftentimes facies that are the same facies are given 2 different names in different state geological maps.  If this occurs, the type locality of the rock is determined (IE, the best-represented sample of that rock), and the facies name is given based on the state the type locality is in.
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First it's igneous rock-weathering/erosion-sediment-pressure and cementation-sedimentary rock-heat and pressure-Metamorphic rock-melting magma cool to be igneous rock
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What is usually meant by an aquifer is a given formation that contains potable water.  There are many aquifers in the world.  A formation could be made from almost any kind of sediment that is both porous and permeable.  In other words, as long as the sediment contains spaces that allows it to hold water, and those spaces are connected together which allows the water to flow.\n\nAs to where the sediments come from, there are various possible sources.  Sediment is the pieces and fragments broken from other rocks.  These other rocks can be igneous (volcanic), metamorphic or even other sediments.  Sedimentary rocks can even be laid down by chemical processes.  \n\nA sediment's orginal composition depends almost entirely on what minerals the parent rock contains.  As a sediment is buried it is compressed, de-watered and heated.  The fragments may become cemented together and turned to rock.  This process is known as diagenesis.  Some of the original mineral are lost as they are turned  to clay during this process.  In order for a rock to be an effective aquifer however, the clay content should be low, as too much clay will lead to the blocking of the passages between the pores.\n\nQuartz, the mineral that makes up common sand, is resistant to chemical alteration, so sandstone is a common (but by no means the only) aquifer rock.
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you need to see whethre the "grains " ae INTERLOCKING, or fixed togethre with a cement. Interlocking grains, whee there are no spaces between them (the "grains" wi be crstals of quartz, felspar and ther minerals depending on type of rock) are indicative of an igneous rock. (or metamorphic) rock. sdimentar rocks are generally made of "clasts" or grains cemented together with a matrix or cement. here are some exceptions to this like evaporites, eg rock salt.
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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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The rocks are no problem. You can go outside & find those.\n\nIgneous rocks include granite & diorite which are relatively easy to find. They are commonly used around driveways & railroad tracks.\n\nSedimentary rocks can be shale, sandstones, conglomerates, limestone, mudstones, etc. Depending on where you live it may be harder to find these.\n\nMetamorphic rocks might also be a problem unless you live somewhere near the mountains. If you have a piece of marble or slate used in flooring & countertops, they are easier to get a hold of.\n\nThe fossils are harder to get unless you actually go out to a riverbed or live near a site known to contain fossils. Your best bet would be to search the net for a reputable dealer or find a store near where you live.\n\nHappy rock & fossil hunting & good luck on the project. :)
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I'm going to assume you are asking about deposition of rock, but am unsure because this is under 'other' and not earth science. \n\nDeposition of rock in the marine environment occurs in at least three ways. The first is by transport, which can be by wind, water, gravity, or ice. Water from rivers carries sediment into ocean basins where it deposits forming deltas, and turbidite deposits on the deeper ocean floor. Wind carries sediment out over the oceans. Gravity causes landslides that often continue into the marine environment, and sometimes take place entirely within the marine environment. Icebergs often carry rock out over the ocean floor and as they melt the rock drops to the sea floor. These ice-transported rocks are known as erratics. \n\nMuch of the deposition of rock material, or what eventually becomes rock, in the marine environment comes from biological sources. Plankton die and sink to the ocean floor, coral reefs build huge platforms (Florida for example) that become limestone rock. Many marine organisms use calcium carbonate to form shells and other parts of their structure, marine algae often contain calcium carbonate, and many microscopic marine organisms precipitate calcium carbonate and some other minerals as part of their biological processes. \n\nChemical deposition also occurs in the marine environment, and deposits of calcium carbonate (very few, but some), salt (halite, sylvite, etc.), and calcium sulfate in the form of gypsum or anhydrite occur as a result of oversaturation conditions in ocean water. Often this deposition only occurs when special conditions exist that confine a portion of an ocean basin and allow the concentrations of dissolved minerals to build up. An example would be the Mediterranean Sea during the Messinian Salinity Crisis in the late Miocene.
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The rock cycle is the continuous movement of rock from one type to another. These processes occur over long amounts of time. All rock started out as igneous. From there, rock can then become sedimentary, metamorphic, or igneous again in any order.\n\nIgneous --> Sedimentary:\nIgneous rocks break down through weathering processes. The broken down rock becomes sediments which are deposited by wind or water. Layers of sediment build up on top of each other. Pressure, along with dissolved minerals, help to "glue" the rock together.\n\nSedimentary --> Metamorphic ("change form"):\nIf the pressure is great & enough heat is applied, metamorphism can occur. This causes the rock to become more compact & dense. If too much heat is applied then the rock will melt. See below.\n\nMetamorphic --> Igneous:\nIf heat is applied to the point of melting, the rock will go though the igneous phase again.\n\n:)
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Geodes form by precipitation of minerals from solution. That would make it a chemical sedimentary rock. \n\nThey are not often found in intrusive igneous rocks because the geode needs a vug, or a cavity within the host rock in order to form. Intrusive igneous rocks rarely have vugs, but do sometimes have large fractures or joints that can be crystal lined similar to a geode. \n\nGeodes are more likely to be found in extrusive igneous rocks that have vugs formed by gas that comes out of solution as the rock cools rapidly (in comparison to intrusive igneous rocks). These vugs eventually may fill with fluid which carries dissolved calcite, quartz, and other minerals. As the fluid becomes oversaturated different minerals will drop out of solution forming layers of the geode and finally forming crystals within the center of the geode. \n\nThe similar things that form in sedimentary rocks are often referred to as concretions, and these are seldom hollow. They may be composed of calcite, chert, or other minerals, and will often have concentric rings within them. However, they do not form within a vug or cavity, but instead appear to grow outward. Septarian concretions have crystalline filled fractures inside them that makes them quite attractive. Concretions appear in most cases to form from a nucleus and grow outward, unlike a geode's growth inward.