Interior of the Earth

 

Earths Structure
  • The internal structure of the earth is layered.
  • The Earth is generally divided into four major layers: the crust, mantle, inner core, and outer core.
  • Earth’s crust is the outermost layer composed of various types of rocks.
  • Below the crust lies the Lithosphere
  • These lithospheric plates appear to “float” and move around on the more ductile asthenosphere
  • The boundary between the crust and mantle is generally called the Mohorovičić discontinuity
  • The continental crust is thicker in comparison to oceanic crust.
  • The lithosphere is the upper 80 Kilometers layer composed of both the crust and part of the upper mantle
  • Earth’s mantle is a rocky shell about 2,890 Kms thick that constitutes about 84 percent of Earth’s volume.
  • The outer core is in the liquid state.
  • The inner core is in solid-state.

Earth’s Crust-

  • There are two types of earth’s crust
Oceanic Crust Continental Crust
  • The oceanic crust is thinner
  • It is composed of basalt
  • It has a high density
  • The continental crust is thicker
  • It is composed of Granite
  • It has low density
  • The low density helps it to flow over the oceanic crust

 

Earth’s Mantle

  • Earth’s mantle has olivine rock.
  • The temperatures increase with depths.
  • The temperature is lowest near the crust and increases with depth.
  • The highest temperatures are found near the mantle material as it is in contact with the heat-producing core.
  • This steady increase of temperature with depth is known as the geothermal gradient.
  • This temperature difference responsible for different rock behaviors, and the different rock behaviors are used to divide the mantle into two different zones.
  • Rocks in the upper mantle are cool and brittle, while rocks in the lower mantle are hot and soft (but not molten).
  • Rocks in the upper mantle are brittle enough to break under stress and produce earthquakes.
  • However, rocks in the lower mantle are soft and flow when subjected to forces instead of breaking.
  • The lower limit of brittle behavior is the boundary between the upper and lower mantle.

Earth’s Core

  • It is composed of alloys of iron and nickel
  • the core gives heat to the inside of earth
  • the radioactive material which is present inside it release heat as they break down into more stable substances.
  • The core is divided into two different zones.
  • The outer core is a liquid because the high temperatures melt the iron-nickel alloy.
  • The inner core is a solid even though its temperature is higher than the outer core because of very high pressure from the weight of rocks lying above it .

Mineral and Energy Resources : NCERT Geography Lesson For class 10th

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Resources 

https://geology.com/nsta/earth-internal-structure.shtml

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