Rock Classification & Rock Cycle

Lauren Chapman Block 3

The Rock Cycle

The rock cycle is the continual process by which new rock forms from old rock material.

Igneous becomes sedimentary through a series of six steps. The first step is to weather down the rocks to form sediments. Then erosion transport the sediments and after that deposition happens which is when the sediments stop moving. Then the sediments are buried, compacted, and then cemented. This process is also called lithification. Igneous becomes metamorphic when heat a pressure are added. An example would be granite turning into gneiss.

Sedimentary can become metamorphic when heat and pressure are added. An example would be sandstone becoming quartzite and limestone becoming marble. Sedimentary becomes igneous when it melts into magma and then cools into igneous.

Metamorphic becomes igneous in 2 steps. It first melts into magma and then the magma cools into igneous rock. Metamorphic rock becomes sedimentary when it goes through the same six steps as igneous rock becoming sedimentary weathering erosion, deposition, bury, compact, and cement. Sedimentary becomes igneous when it melts into magma and then cools into igneous.

Igneous Rock

Igneous rock forms when hot, liquid rock (magma) cools and solidifies. When the magma cools it hardens into igneous rock. The type of igneous rock that forms all depends on the composition of the magma.

There are two methods of classifying igneous rocks. They are extrusive and intrusive. Extrusive is when the rock is formed on the Earth's surface. Extrusive rocks usually have small fine grains. Intrusive is when the rock is formed beneath the Earth's surface. Intrusive has coarse grains.

The characteristics of igneous rocks differ from one another. The light-colored rocks are less dense than the darker colored rocks. The light colored rocks are rich in the elements aluminum, potassium, silicon, and sodium. They are also called felsic rocks. Darker colored rocks are denser than the lighter colored. They are called mafic rocks.

Intrusive Igneous Rock
Extrusive Igneous Rock

Sedimentary Rock

Sedimentary rock forms when erosion moves mineral fragments from one place to another and they are deposited in layers. New layers are deposited on top of the older layers. Dissolved minerals separate from the water to form a natural cement that binds the rock and fragments together.

Sedimentary rocks can be used to learn more about history. Some sedimentary rocks have fossils of animals or plants inside of them. These fossil can be used by scientist to learn more about the history of a certain time period or the history of that area.

Sedimentary rock is classified by the way in forms and texture. Clastic sedimentary rock forms when mineral fragments (clasts) are cemented together. Chemical sedimentary rock forms when minerals crystallize out of a solution to become rock. Organic sedimentary rock forms from the remains of once-living plants and animals.

The most noticeable characteristic or feature of sedimentary rock is it's strata. Strata is the same thing as layers. Stratification is the process in which sedimentary rocks are arranged in layers. Strata differ from one another depending on the kind, size, and color of their sediment.

Organic Sedimentary Rock
Chemical Sedimentary Rock

Metamorphic Rock

Metamorphic rocks are rocks where their structure, texture, or composition has changed. They are formed through metamorphism. Metamorphism is when the rock undergoes a change in temperature or pressure. This mainly occurs deep down in the Earth's crust.

Metamorphic rock is classified by its texture. Metamorphic rock has one of two textures. The textures include foliated or nonfoliated. Foliated is when the mineral grains of the rock are arranged in planes or bands. Nonfoliated is when the mineral grains are not arranged in planes or bands.

Metamorphic rock has features that tell you about its history. These features are caused by deformation which is a change in the shape of a rock cause by a forced placed on it. These forces can cause a rock to be squeezed or stretched. Metamorphic rocks can have folds or bends which indicate that a rock has been deformed. However, some folds are not visible to the naked eye

Foliated Metamorphic Rock
Nonfoliated Metamorphic Rock

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