ABM Grade 12 Modules and activities! 2022-2023

Earth and Life Science part2

What makes up the crust of the earth?

What is crust? Crust is outermost, solid shell that makes up the surface of a rocky planet such as earth.

The crust is composed of great variety of igneous, metamorphic, and sedimentary rocks.

Igneous rock is a type of rock that formed as a result of solidification of lava when a volcano erupts. And there are two basic types of igneous rocks; intrusive igneous rock and extrusive igneous rock.

Diorite, granite, and pegmatite are examples of igneous rocks.

Metamorphic rock is a type of rock that have been modified by heat, pressure, and chemical processes usually while buried deep below the Earth's surface.

Slate and marble are examples of metamorphic rocks.

Sedimentary rock is a type of rock formed by the accumulation of sediments. There are three basic types of sedimentary rocks: clastic, chemical and organic sedimentary rocks.

Sandstone, limestone, and coal are examples of sedimentary rocks.

The rocks found in the crust consist mostly of ligher elements such as silicon, potassium, and sodium.

The Earth's crust is made of rocks, which in turn are composed of minerals.

Mineral, a naturally occurring substance substance that build up the earth's crust. They are many types of minerals, but they all have some characteristics common to each other. These characteristics include the following:

1. Minerals are crystalline solids.
2. Minerals are made of chemical elements and compounds.
3. Minerals have known chemical compositions.
4. Minerals are inorganic in nature.

Minerals display a highly ordered internal atomic structure that has a regular geometric form such as Ouartz, Diamond, Topaz, Garnet, and etc. because of this feature, minerals are classified as crystalline solids. Both elements and compounds can be minerals. A mineral is a solid, inorganic, naturally occurring, crystalline substance with a fixed chemical composition. For example, Diamond is pure carbon, so it is a mineral made of only one element. A mineral has one specific chemical composition and is generally inorganic even though some may contain carbon.

Most minerals are derived or extracted from nature through the process of mining. They are generally made of higher form of elements like iron, magnesium, chromiun, and solicon. These are usually crystalline solids with definite shape and structure. They are substance, however that meet the five criteria but do not have definite shape or crystallinity. These amorphous minerals are classified as mineraloids.

Minerals are present everywhere and some examples of these can be found at home. Diamond rings, aluminum foil, and talcum powder are made of minerals.

And there are two types of earth's crust: the oceanic crust and continental crust.

Oceanic crust, extending 5-10 kilometers beneath the ocean floor, is mostly composed of different types of basalts. Geologists often refer to the rocks of the oceanic crust as "sima." Sima stands for silicate and magnesium, the most abundant minerals in oceanic crust. Oceanic crust is constantly formed at mid-ocean ridges, where tectonic plates are tearing apart from each other.

continental crust, the outermost layer of Earth's lithosphere that makes up the planet's continents and continental shelves and is formed near subduction zones at plate boundaries between continental and oceanic tectonic plates. The continental crust forms nearly all of Earth's land surface.

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The cycle has no beginning and no end. 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.