Geography

Characteristics and Examples of Igneous, Sedimentary and Metamorphic Rocks

len Alfred Ajibola - Thu, 24th January, 2019 @ 18:28:55 PM

Topics in Geography

Branches of Geography: Physical and Environmental Geography Geography Scheme of Work, SS1, First Term Geography Scheme of Work, SS1, Second Term Geography Scheme of Work, SS1, Third Term Classification | Types of Planets and their Characteristics Planets of the Solar System with their Characteristics Functions of the Atmosphere Layers of the Atmosphere Solar System in Geography Atmosphere: Composition of the Atmosphere Geography, Types and Branches of Geography Characteristics and Examples of Igneous, Sedimentary and Metamorphic Rocks


Academic Questions in Geography

Please check out our Test Your Knowledge page to see all Questions and Answers

The following are true concerning the gas planets except _____.

  • A. Neptune is an example of a gas planet

  • B. They are also referred to as jovian planets

  • C. They have rings around them

  • D. They are smaller in size when compared to earth

  • E. They are also referred to as gas giants

  • F. They are composed mainly of hydrogen and helium gas

The following are characteristics of terrestrial planets except _____.

  • A. They have rocky surfaces

  • B. Their surfaces are compact in nature

  • C. They have no rings around them

  • D. Uranus is an example of terrestrial planet

  • E. They rotate slowly around their satellites

  • F. The have few number of satellites

Planets can be classified under the following headings except _____.

  • A. Size

  • B. Shape

  • C. Mass

  • D. Time of discovery

  • E. Composition

  • F. Relative positioning to the sun

The following are branches of physiography except _____.

  • A. Oceanography

  • B. Geomorphology

  • C. Envirogeography

  • D. Paleography

  • E. Glaciology

  • F. Bio-Geography

Sedimentary rocks are formed from the following processes EXCEPT _____.

  • A. By the transformation of a protolith

  • B. By the transportation and subsequent deposition of weathered remains of pre-existing rocks

  • C. By the accumulation and lithification of detrital rocks

  • D. By their precipitation from solution

  • E. By processes resulting from biogenic activity

  • F. All of the above

The following are examples of igneous rock EXCEPT _____.

  • A. Tuff

  • B. Gneiss

  • C. Granite

  • D. Pegmatite

  • E. Gabbro

  • F. Pumice

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Types of Rock:

We have 3 main types or classes of rock based on how they are formed. These are:

  1. Igneous Rock
  2. sedimentary Rock
  3. metamorphic Rock

 

Igneous Rock

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Igneous rocks are formed when molten substances below the earth surface cools down and solidifies. These molten substances are called magma or lava. Magma can be derived from melting of existing rocks on the earth crust.

The solidification of molten magma into igneous rock may be below the earth's surface (intrusive) or on the earth's surface (extrusive), giving rise to the two types of igneous rock.

  • Intrusive Igneous Rock: These are igneous rocks that crystallizes below the earth’s surface. They generally cool slowly during the process of solidification and tend to produce large crystals.

    Intrusive Igneous Rock are also referred to as Plutonic Igneous Rock. Examples are gabbro, granite and pegmatite.

  • Extrusive Igneous Rock: They are igneous rocks that form when molten magma erupts on top of the earth's surface. They cool down and solidify quickly, producing small crystals in the process.  Sometimes, the molten magma cools so quickly, allowing no time for crystals to grow. This rapid cooling results in the formation of an amorphous glass.

    Extrusive Igneous Rock are also referred to as Volcanic Igneous Rock. Examples are basalt, rhyolite and scoria.

 

Sedimentary Rock

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Sedimentary rocks amount to about 76% of the earth's surface. They can be formed in different ways;

  • By the deposition of the weathered remains of pre-existing rocks and their subsequent transportation and deposition. Sedimentary rocks formed in this way are known as clastic sedimentary rock.
  • By the accumulation and lithification of sediment or detrital rock.
  • By the precipitation from solution. Sedimentary rocks formed in this way are known as chemical sedimentary rock.
  • As a result of biogenic activities. Sedimentary rocks formed in this way are known as organic sedimentary rock.

    Please read on Separation Techniques here.

Clastic sedimentary rock require 4 basic processes during their formation. These are:

  1. Weathering
  2. Transportation
  3. Deposition
  4. Compaction

Please read on Soil Erosion here.

Examples of Sedimentary rocks include chalk, limestone, sandstone and clay.

Note the followings:

Weathering refers to the processes that involves the physical and chemical breakdown of rocks when exposed to the air and water.

Lithification is a process of rock formation whereby pressure squeezes the rock sediments into layered solids while the connate fluids are expelled.

Diagenesis is a term used to describe all the chemical, physical, and biological changes a sediment undergoes after its initial deposition and lithification.

Diagenesis is not dependent on surface weathering.

From the above explanation, we can conclude that there are three basic types of sedimentary rocks based on their formation process. These are:

  • Clastic sedimentary rocks: They are formed from mechanical weathering of pre-existing rocks. Examples are breccia, sandstone and siltstone
  • Chemical sedimentary rocks: They are formed when materials precipitate from solution. Examples are rock salt, iron ore, and some dolomites solution.
  • Organic sedimentary rocks: They are formed from biogenic activity; that is; the accumulation of plant and animal debris. Examples are coal, dolomites and some limestones.

 

Metamorphic Rock

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Metamorphic rocks are formed from the transformation of an existing rock or original rock called protolith. The protolith may be an igneous rock or a sedimentary rock or another older metamorphic rock. Their transformation may be physical or chemical, requiring great heat and pressure.

Metamorphic rocks are always more dense and also less likely to be broken down by erosion when compared to igneous and sedimentary rocks. They make up about 12% of the earth crust and can also be formed beneath the earth surface.

Note:

Examples of metamorphic rocks are schist (a converted basalt), quartzite (a compressed sandstone), and marble (a compressed limestone or dolomite).

We have two basic types of metamorphic rocks based on their appearances. They are:

  1. Foliated metamorphic rocks: They have a layered or banded appearance. Gneiss and Schist are examples.
  2. Non-foliated metamorphic rocks: They don't have a layered or banded appearance. Marble and Quartzite are examples.

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Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.


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Only 2 countries have the color purple in their national flag. Both countries are:

Nicaragua and Dominica

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The shortest war in history lasted for only 38 minutes

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Earth is the only planet that contains water on it's surface. In fact, the percentage of water on Earth is greater than that of land.

Water: 71%

Land: 21%

Salt water or Saline water makes up about 97% of Earth's water. It comprises majorly of ocean and sea waters

Metal actually rains on planet Venus

Planet Mars appear brownish or reddish because it's covered with iron rust


NOTABLE POINTS IN Geography

We have 3 main types or classes of rock based on how they are formed. These are:

1. Igneous Rock

 

2. Sedimentary Rock

 

3. Metamorphic Rock

 

Igneous rocks are formed when molten substances below the earth surface cools down and solidifies. These molten substances are called magma or lava. Magma can be derived from melting of existing rocks on the earth crust.

The solidification of molten magma into igneous rock may be below the earth's surface (intrusive) or on the earth's surface (extrusive), giving rise to the two types of igneous rock.

  • Intrusive Igneous Rock: These are igneous rocks that crystallizes below the earth’s surface. They generally cool slowly during the process of solidification and tend to produce large crystals.

    Intrusive Igneous Rock are also referred to as Plutonic Igneous Rock. Examples are gabbro, granite and pegmatite.

  • Extrusive Igneous Rock: They are igneous rocks that form when molten magma erupts on top of the earth's surface. They cool down and solidify quickly, producing small crystals in the process.  Sometimes, the molten magma cools so quickly, allowing no time for crystals to grow. This rapid cooling results in the formation of an amorphous glass.

    Extrusive Igneous Rock are also referred to as Volcanic Igneous Rock. Examples are basalt, rhyolite and scoria.

Sedimentary rocks amount to about 76% of the earth's surface. They can be formed in different ways. These are:

  • By the deposition of the weathered remains of pre-existing rocks and their subsequent transportation and deposition. Sedimentary rocks formed in this way are known as clastic sedimentary rock.

  • By the accumulation and lithification of sediment or detrital rock.

  • By their precipitation from solution. Sedimentary rocks formed in this way are known as chemical sedimentary rock.

  • As a result of biogenic activities. Sedimentary rocks formed in this way are known as organic sedimentary rock.

Please read more on types of rocks here

Metamorphic rocks are formed from the transformation of an existing rock or original rock called protolith. The protolith may be an igneous rock or a sedimentary rock or another older metamorphic rock. Their transformation may be physical or chemical, requiring great heat and pressure.

Metamorphic rocks are always more dense and also less likely to be broken down by erosion when compared to igneous and sedimentary rocks. They make up about 12% of the earth crust and can also be formed beneath the earth surface.

Examples of metamorphic rocks are schist (a converted basalt), quartzite (a compressed sandstone), and marble (a compressed limestone or dolomite).