Structure of the Earth



Listed here are quick facts about the earth’s crust, mantle, and core.


The crust the outer layer of the Earth varying between 5 to 50 km in depth under the surface of the earth.  The crust is the outermost and thinnest layer of the earth’s surface. The crust comprises about 5% of the earth body.  The thickness of the crust is more under the continents and lesser under oceans. The outermost layer of the crust is composed of lighter silicates termed as sial (Silica +Aluminium).  Moho or Mohorovicic discontinuity separates crust from mantle.


The mantle is the portion of the earth that is made up of iron and magnesium silicates, with temperature ranging up to 16000 C and extends downwords to a depth of about 1000 km. The thickness of the lower mantle is about 1900 km.  The mantle contains 83% of the total volume and 68% of the total mass of the earth.  The mantle is separated from the core by Gutenberg discontinuity. It is largely composed of silicon and magnesium called sima. The rocks in this layer may be in the glassy state.


There are two parts of the earth’s core.  The outer core, approximately 2100 km thick, consists of molten iron and nickel with temperatures ranging between 20000 C and 50000 C. Below this is the solid inner core which has diameter of 2,740 km.  The core is the central region of the earth. It is 3475 km in radius. By volume, it is 16% of the earth body . By mass, it constitutes 32% of the mass of the earth. The temperature of the inner core is 60000 C – 70000 C. The inner core is composed of NiFe (Ni for Nickel Fe for Iron.).


Structure of the earth: crust, mantle, and core.

Structure of the earth: crust, mantle, and core.

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