What is the Earth?

Earth is the place we call home. It is the only known planet to have living organisms.

The Earth takes approximately 365 days to orbit the sun. The Earth’s surface consists of around 71% water and 29% land. Earth also has a mixture of gases such as oxygen, carbon dioxide, nitrogen, and argon which we need to survive.

The Earth is made up of approximately 70% water. Liquid water is found in seas, oceans, rivers, lakes, and underground. Solid ice is found in snow and glaciers; this is usually in the cold regions on Earth such as the North Pole and the South Pole. The gaseous state that water exists is called water vapour. Water vapour is found in the Earth’s atmosphere. 

The water cycle is the path that water takes around the Earth. Water moves from land to the sky and back again.

What are the layers of Earth?

The Earth has four layers. These layers include:

  • Crust
  • Mantle
  • Outer core
  • Inner core

Crust

The crust is the thin outer layer of the Earth, it is only 1% of the whole Earth. It is the solid rock layer that we live on. All living and non-living organisms exist on the crust of the Earth. The Earth’s crust is split into two categories known as continental crust or oceanic crust.

The continental crust is essentially the dry land on Earth made up of mostly rock. This type of crust is thick and less dense.

The oceanic crust is anything below the sea level, including the thin layers holding seas and oceans. It is mainly made up of rock basalt. This type of crust is thin and dense.

The Earth’s crust is split into many pieces known as tectonic plates. The tectonic plates move around freely on the lower liquid layer known as the mantle.

There are seven major plates:

  • North American
  • South American
  • African
  • Eurasian
  • Antarctic
  • Australian
  • Pacific 

Mantle 

The mantle is the thickest section of the Earth. It makes up about 84% of the Earth’s volume. This layer is mostly made up of magma which is a semi-molten rock. Over time this molten rock has solidified to form what is it today. 

The temperature of the mantle differs depending on the depth. The mantle has two layers, the upper mantle, and the lower mantle. Temperatures closer to the crust (upper mantle) are cooler than temperatures deeper within the mantle (lower mantle). 

The tectonic plates located at the Earth’s crust are free-floating on the mantle. This is what allows for the mobility of the plates. 

Outer core

The outer core is the thick layer below the mantle that surrounds the inner core. It is a liquid layer made up of liquid iron and nickel. The outer core has extremely high temperatures, which allow the iron and liquid to keep their liquid forms. 

Inner core

The inner core is right in the center of the Earth. It is the hottest part. The inner core is solid, and it is made up of iron and nickel. This highly pressurized, hot solid ball is protected by the outer core, mantle, and crust. The temperatures are intently high, reaching nearly the same temperature as the sun.  

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What are the layers of soil?

There are five layers of soil. These layers include:

  • Organic layer
  • Topsoil
  • Subsoil
  • Parent material
  • Bedrock

Soil is the top layer of the Earth’s crust, consisting of minerals, organisms, and chemicals. Soil is home to many plants and animals. The layers of soil are also known as horizons.

Soil is a vital part of Earth as it supports life on Earth, such as living organisms, water, and the atmosphere.
Soil also provides a home for living organisms to live. These include plants, animals, bacteria, and fungi.
Soil provides the correct nutrients for these organisms to survive and grow. It also provides support as the plants use the soil to anchor themselves using their long roots. This prevents the plants from being pulled out of the soil easily by the weather or animals.The soil is able to help with filtering and cleaning water. Alongside this, soil plays an important role in the cycling of nutrients such as nitrogen and carbon.
Lastly, the soil is known to store a lot of carbon which helps to remove carbon dioxide from the atmosphere.

Organic layer

The organic layer is also known as the O horizon. The organic layer is the top layer consisting of plant remains such as leaves, twigs, and other organic materials which have decomposed and formed hummus. Humus contains many nutrient materials that are required to improve the health and fertility of the soil. We can identify how fertile the soil is at this layer.

Topsoil

Topsoil is also known as A horizon. The topsoil is the layer consisting of organic matter and minerals which help plant growth. This is the layer in which we plant seeds. Both plants and organisms live in this layer. 

Subsoil

Subsoil is also known as B horizon. The subsoil is a compact layer consisting of organic matter, clay, and minerals. It is a hard layer that some long roots can reach. 

Parent material 

Parent material is also known as C horizon. The parent material is the layer of soil consisting of large rocks. The upper layers of soil are developed from this layer. There is no organic matter or plants in this layer. 

Bedrock 

Bedrock is the bottom layer. It is the hardest layer as it mainly consists of large solid rocks such as limestone, sandstone, granite, basalt, etc. 

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What are the types of rocks on Earth?

There are three types of rocks on Earth. Each type of rock has different properties and are found in different areas. Each type of rock is formed in different ways. 

The types of rocks are:

  • Igneous rocks 
  • Sedimentary rocks
  • Metamorphic rocks

What are igneous rocks?

Igneous rocks are made from melted rocks and minerals. They form when magma cools down and solidifies.

An example of an igneous rock is granite. 

What are sedimentary rocks?

Sedimentary rocks are made from lots of small pieces of material such as small rocks, plant, or animal remains. They are formed from sediment that has settled at the bottom of lakes, seas, and oceans. This sediment has been compressed over time and the rocks form layers on top of one another. Fossils are mostly found in sedimentary rocks.

An example of a sedimentary rock is limestone. 

What are metamorphic rocks?

Metamorphic rocks are formed when igneous or sedimentary rocks are heated at a high temperature and then compressed under great pressure. The high temperature and pressure causes the rocks to change into other types of rocks. This process takes a very long time.

An example of a metamorphic rock is marble. Marble originates from limestone.

Fossils are remains of plants and animals that are imprinted in rocks. Scientists are able to identify changes that have occurred to plants and animals over time. 

Fossilisation is the process by which a fossil is formed, this process requires specific conditions. Fossils are mostly found in sedimentary rocks

How are fossils formed? 

Fossils require specific conditions in order for them to form. When an animal dies the dead remains sink to the ground and slowly get covered in mud and sand. The soft parts of its body decompose leaving the hard parts such as the skeleton. Over time more layers of sediment form on top and the sediment around the skeleton starts to compact and turn into rock. The bones then begin to dissolve in water. The minerals in the water replace the bone which leaves a print of the animal on the rock.  

Fossils provide us with evidence of extinct animals such as dinosaurs and mammoths. 

There are different ways of describing fossil preservation: 

  • Compression 
  • Petrification 
  • Moulds and casts
  • Preserved remains 

Compression is the process in which a dark imprint of the is fossil preserved in sedimentary rock that has undergone physical compression due to high-pressure forces. 

Petrification is the process in which organic matter is exposed to minerals. Over long periods of time, it is turned into a stony substance. 

Moulds are produced where the original bone or shell is dissolved, leaving a space in the shape of the original material. Over time sediment can fill the space to form a cast

Preserved remains are rare as it is the preservation of the original soft body or skeleton of organisms. 

Watch the video

What is the Earth?

Earth is the place we call home. It is the only known planet to have living organisms.

The Earth takes approximately 365 days to orbit the sun. The Earth’s surface consists of around 71% water and 29% land. Earth also has a mixture of gases such as oxygen, carbon dioxide, nitrogen, and argon which we need to survive.

The Earth is made up of approximately 70% water. Liquid water is found in seas, oceans, rivers, lakes, and underground. Solid ice is found in snow and glaciers; this is usually in the cold regions on Earth such as the North Pole and the South Pole. The gaseous state that water exists is called water vapour. Water vapour is found in the Earth’s atmosphere. 

The water cycle is the path that water takes around the Earth. Water moves from land to the sky and back again.

What are the layers of Earth?

The Earth has four layers. These layers include:

  • Crust
  • Mantle
  • Outer core
  • Inner core

Crust

The crust is the thin outer layer of the Earth, it is only 1% of the whole Earth. It is the solid rock layer that we live on. All living and non-living organisms exist on the crust of the Earth. The Earth’s crust is split into two categories known as continental crust or oceanic crust.

The continental crust is essentially the dry land on Earth made up of mostly rock. This type of crust is thick and less dense.

The oceanic crust is anything below the sea level, including the thin layers holding seas and oceans. It is mainly made up of rock basalt. This type of crust is thin and dense.

The Earth’s crust is split into many pieces known as tectonic plates. The tectonic plates move around freely on the lower liquid layer known as the mantle.

There are seven major plates:

  • North American
  • South American
  • African
  • Eurasian
  • Antarctic
  • Australian
  • Pacific 

Mantle 

The mantle is the thickest section of the Earth. It makes up about 84% of the Earth’s volume. This layer is mostly made up of magma which is a semi-molten rock. Over time this molten rock has solidified to form what is it today. 

The temperature of the mantle differs depending on the depth. The mantle has two layers, the upper mantle, and the lower mantle. Temperatures closer to the crust (upper mantle) are cooler than temperatures deeper within the mantle (lower mantle). 

The tectonic plates located at the Earth’s crust are free-floating on the mantle. This is what allows for the mobility of the plates. 

Outer core

The outer core is the thick layer below the mantle that surrounds the inner core. It is a liquid layer made up of liquid iron and nickel. The outer core has extremely high temperatures, which allow the iron and liquid to keep their liquid forms. 

Inner core

The inner core is right in the center of the Earth. It is the hottest part. The inner core is solid, and it is made up of iron and nickel. This highly pressurized, hot solid ball is protected by the outer core, mantle, and crust. The temperatures are intently high, reaching nearly the same temperature as the sun.  

Watch the video

What are the layers of soil?

There are five layers of soil. These layers include:

  • Organic layer
  • Topsoil
  • Subsoil
  • Parent material
  • Bedrock

Soil is the top layer of the Earth’s crust, consisting of minerals, organisms, and chemicals. Soil is home to many plants and animals. The layers of soil are also known as horizons.

Soil is a vital part of Earth as it supports life on Earth, such as living organisms, water, and the atmosphere.
Soil also provides a home for living organisms to live. These include plants, animals, bacteria, and fungi.
Soil provides the correct nutrients for these organisms to survive and grow. It also provides support as the plants use the soil to anchor themselves using their long roots. This prevents the plants from being pulled out of the soil easily by the weather or animals.The soil is able to help with filtering and cleaning water. Alongside this, soil plays an important role in the cycling of nutrients such as nitrogen and carbon.
Lastly, the soil is known to store a lot of carbon which helps to remove carbon dioxide from the atmosphere.

Organic layer

The organic layer is also known as the O horizon. The organic layer is the top layer consisting of plant remains such as leaves, twigs, and other organic materials which have decomposed and formed hummus. Humus contains many nutrient materials that are required to improve the health and fertility of the soil. We can identify how fertile the soil is at this layer.

Topsoil

Topsoil is also known as A horizon. The topsoil is the layer consisting of organic matter and minerals which help plant growth. This is the layer in which we plant seeds. Both plants and organisms live in this layer. 

Subsoil

Subsoil is also known as B horizon. The subsoil is a compact layer consisting of organic matter, clay, and minerals. It is a hard layer that some long roots can reach. 

Parent material 

Parent material is also known as C horizon. The parent material is the layer of soil consisting of large rocks. The upper layers of soil are developed from this layer. There is no organic matter or plants in this layer. 

Bedrock 

Bedrock is the bottom layer. It is the hardest layer as it mainly consists of large solid rocks such as limestone, sandstone, granite, basalt, etc. 

Watch the video

What are the types of rocks on Earth?

There are three types of rocks on Earth. Each type of rock has different properties and are found in different areas. Each type of rock is formed in different ways. 

The types of rocks are:

  • Igneous rocks 
  • Sedimentary rocks
  • Metamorphic rocks

What are igneous rocks?

Igneous rocks are made from melted rocks and minerals. They form when magma cools down and solidifies.

An example of an igneous rock is granite. 

What are sedimentary rocks?

Sedimentary rocks are made from lots of small pieces of material such as small rocks, plant, or animal remains. They are formed from sediment that has settled at the bottom of lakes, seas, and oceans. This sediment has been compressed over time and the rocks form layers on top of one another. Fossils are mostly found in sedimentary rocks.

An example of a sedimentary rock is limestone. 

What are metamorphic rocks?

Metamorphic rocks are formed when igneous or sedimentary rocks are heated at a high temperature and then compressed under great pressure. The high temperature and pressure causes the rocks to change into other types of rocks. This process takes a very long time.

An example of a metamorphic rock is marble. Marble originates from limestone.

Fossils are remains of plants and animals that are imprinted in rocks. Scientists are able to identify changes that have occurred to plants and animals over time. 

Fossilisation is the process by which a fossil is formed, this process requires specific conditions. Fossils are mostly found in sedimentary rocks

How are fossils formed? 

Fossils require specific conditions in order for them to form. When an animal dies the dead remains sink to the ground and slowly get covered in mud and sand. The soft parts of its body decompose leaving the hard parts such as the skeleton. Over time more layers of sediment form on top and the sediment around the skeleton starts to compact and turn into rock. The bones then begin to dissolve in water. The minerals in the water replace the bone which leaves a print of the animal on the rock.  

Fossils provide us with evidence of extinct animals such as dinosaurs and mammoths. 

There are different ways of describing fossil preservation: 

  • Compression 
  • Petrification 
  • Moulds and casts
  • Preserved remains 

Compression is the process in which a dark imprint of the is fossil preserved in sedimentary rock that has undergone physical compression due to high-pressure forces. 

Petrification is the process in which organic matter is exposed to minerals. Over long periods of time, it is turned into a stony substance. 

Moulds are produced where the original bone or shell is dissolved, leaving a space in the shape of the original material. Over time sediment can fill the space to form a cast

Preserved remains are rare as it is the preservation of the original soft body or skeleton of organisms. 

Watch the video