rocks and processes of the rock cycle

crystallization

Magma cools either underground or on the surface and hardens into an igneous rock. As the magma cools, different crystals form at different temperatures, undergoing crystallization. For example, the mineral olivine crystallizes out of magma at much higher temperatures than quartz. The rate of cooling determines how much time the crystals will have to form. Slow cooling produces larger crystals.

erosion and sedimentation

Weathering wears rocks at the Earths surface down into smaller pieces. The small fragments are called sediments. Running water, ice, and gravity all transport these sediments from one place to another by erosion. During sedimen- tation, the sediments are laid down or deposited. In order to form a sedimentary rock, the accumulated sediment must become compacted and cemented together.

the three rock types

Rocks are classified into three major groups according to how they form. These three types are described in more detail in other concepts in this chapter, but here is a summary. The Rock Cycle. Igneous rocks form from the cooling and hardening of molten magma in many different environments. The chemical composition of the magma and the rate at which it cools determine what rock forms. Igneous rocks can cool slowly beneath the surface or rapidly at the surface. These rocks are identified by their composition and texture. More than 700 different types of igneous rocks are known. Sedimentary rocks form by the compaction and cementing together of sediments, broken pieces of rock-like gravel, sand, silt, or clay. Those sediments can be formed from the weathering and erosion of preexisting rocks. Sedimentary rocks also include chemical precipitates, the solid materials left behind after a liquid evaporates. Metamorphic rocks form when the minerals in an existing rock are changed by heat or pressure below the surface. Click image to the left or use the URL below. URL:

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the processes of the rock cycle

Several processes can turn one type of rock into another type of rock. The key processes of the rock cycle are crystallization, erosion and sedimentation, and metamorphism.

the rock cycle

The rock cycle, illustrated in Figure 1.1, depicts how the three major rock types - igneous, sedimentary, and meta- morphic - convert from one to another. Arrows connecting the rock types represent the processes that accomplish these changes. Rocks change as a result of natural processes that are taking place all the time. Most changes happen very slowly. Rocks deep within the Earth are right now becoming other types of rocks. Rocks at the surface are lying in place before they are next exposed to a process that will change them. Even at the surface, we may not notice the changes. The rock cycle has no beginning or end.

metamorphism

When a rock is exposed to extreme heat and pressure within the Earth but does not melt, the rock becomes meta- morphosed. Metamorphism may change the mineral composition and the texture of the rock. For that reason, a metamorphic rock may have a new mineral composition and/or texture.

instructional diagrams

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questions

all rocks and rock types are part of the rock cycle.

-->  a) true

b) false

rocks are classified into four major groups, reflecting how they formed: intrusive, extrusive, metamorphic and sedimentary.

a) true

-->  b) false

what determines the type of igneous rock that forms from magma?

a) the heat and pressure the magma is exposed to.

b) whether the magma enters water before it cools

-->  c) magma composition and cooling rate

d) the amount of compaction and cementation that affect the rock.

which of the following characteristics of a rock is affected by the cooling rate of magma?

a) the rocks color.

-->  b) the rocks texture.

c) the rocks hardness.

d) the rocks chemical composition.

which of the following is a process of the rock cycle?

a) weathering

b) crystallization

c) metamorphosis

-->  d) all of these

a rock is heated so much that it melts. what type of rock will it become?

-->  a) igneous

b) metamorphic

c) sedimentary

d) fossil

in crystallization, slower cooling forms smaller crystals.

a) true

-->  b) false

_____ happens when solid material separates out of a liquid, usually when the liquid evaporates.

a) weathering

b) erosion

c) sedimentation

-->  d) precipitation

a rock transforms from one type to another by the processes of the rock cycle, but once it is transformed it is out of the rock cycle.

a) true

-->  b) false

diagram questions

No diagram questions associated with this lesson