describe the layers of the interior of the earth and their chemical copmposition
Answers
Explanation:
The Inner Structure of the Earth
We have information about the inner structure of the Earth from seismic waves. When an earthquake occurs, by the measurement and examination of the seismic waves we can identify differences in density and physical state inside the Earth.
Within the Earth, different layers alter one after another with increasing depth. This alteration can be recognized according to the chemical composition and the physical properties.
Layers of Differing Chemical Composition
To determine the chemical composition inside the Earth indirect measurements are used. One way to determine composition is to measure how the density of rock changes with depth below the Earth’s surface. We can do this by measuring the speeds with which earthquake waves pass through the Earth, because they move more quickly through dense rocks than through less dense rocks. From such measurements we know that density increases with depth, but not smoothly. At some depths abrupt velocity increases indicate sudden increases in density. Knowing these different densities, we can estimate what the composition of the different layers must be.
The layers of different chemical composition outward from the centre of the Earth are as follows: core, mantle, and crust.
The Core
At the centre is the densest of the three layers, the core. It is mostly metallic iron with small amounts of nickel and other elements. The outer boundary of core is at a depth of 2,900 kilometres.
The Mantle
The thick shell of the dense, rocky matter that surrounds the core is called the mantle. The mantle consists of iron-magnesium-silicates and it is less dense than the core but denser than the outermost compositional layer, which also consists of rocky matter. The outer boundary of the mantle is at a depth from 8-70 km.