According to the classification of the inner structure of the earth by suess, the upper part of the crust is made up of Earth’s sedimanentary rocks. Under this part, Suess has divided the crust internal state of the earth mainly on the basis of the chemical composition.
1. Sial: According to Suess, it is the uppermost layer of the Earth in which the substances called silica and aluminum are obtained. Therefore this layer is called Sial (Si + al = Sial). The average density of this layer is 2.9 grams per cubic cm. The average depth of this layer is 50 – 300 km. In this layer, the acid content is prominent. It contains rocky stones, basaltic rocks, granite rocks, etc.
2. Sima: According to Suess, it is the intermediate layer of the Earth, which has the dominance of silica and magnesium. Therefore this layer is called the sima (Si + ma = Sima). The density of this layer is 2.9 – 4.7 grams per cubic cm. The depth of this layer is found to be 1000 – 2000 km. Its composition is from Basalt and Gebro rocks. It has a dominance of alkaline nature in it. Lava comes out of this layer during volcanic eruption.
3. Nife: According to Suess, it is the innermost layer of the Earth. Nickel and ferrum are present in its formation, so this layer is called (Ni + fe = Nife). The density of this layer is 11 grams per cubic cm. This layer extends from the deepest end of the sima to the earth’s centre. This is the densest layer. The properties of magnetic power exist in it. This classification of Earth presented by Suess is depicted.
