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ashleylynn Group Title

Which of the following is not considered to be a rock? a. coal b. sandstone c. pumice d. lava

  • one year ago
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    • one year ago
  2. Agent_Sniffles Group Title
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    A. Coal Coal is a fuel, not a rock.

    • one year ago
  3. Zontafer Group Title
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    The answer is not coal because coal is a sedimentary rock of biochemical origin. It forms from accumulations of organic matter, likely along the edges of shallow seas and lakes or rivers. Flat swampy areas that are episodically flooded are the best candidates for coal formation. During non-flooding periods of time, thick accumulations of dead plant material pile up. As the water levels rise, the organic debris is covered by water, sand and soils. The water (often salty), sand and soils can prevent the decay and transport of the organic debris. If left alone, the buried organic debris begins to go through the coal series as more and more sand and silt accumulates above it. The compressed and/or heated organic debris begins driving off volatiles, leaving primarily carbon behind. The answer is not sandstone because sandstone is a very common sedimentary rock and perhaps the best known sedimentary rock. It is formed in many environments. Just about anywhere there is water, whether frozen or not, in a river or ocean, there is a chance to form sandstone. Even where there is no water as in a desert, there is sandstone formation under foot The answer is not pumice because pumice rocks are igneous rocks which were formed when lava cooled quickly above ground. You can see where little pockets of air had been. This rock is so light, that many pumice rocks will actually float in water. Pumice is actually a kind of glass and not a mixture of minerals. Because this rock is so light, it is used quite often as a decorative landscape stone. The best answer would probally be lava because lava is kinda rock. Hot, molten rock is called magma. Magma is a mixture of liquid rock, minerals, and dissolved gases. It is formed by the melting of earth's mantle. Magma is found deep below the surface of the earth. This question is a trick questions because one could say lava is a rock since it is melted rock. One could even agure it is not a rock sinse it is not in its rock state. Very confusing question... Hope this helped :)

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