Interior of the Earth
- 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.
- There are two types of earth’s crust
|Oceanic Crust||Continental Crust|
- 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.
- 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 .