Tha earth is made up of four main layers - tha INNER CORE , OUTER CORE the MANTLE and the CRUST . We live on tha outer part of tha earth which is called tha CRUST . This layer consists of the upper 30-100km. The crust mostly consists of igneous rocks; the rest consists of sedimentary and metamorphic rocks. The layer from 0-20 km is called the SIAL as the two main constituents are silicon and aluminum. It is 2.7 times denser than water.tha next layer is known as SIMA as alaege quantity of silicon and magnesium is found in this layer . The averge density of this layer is 3.4 times that of water. The next layer called the MANTLE is 100- 2900km thick. The upper part of the mantle is a plastic layer over which tha crust floats. The mantle is composed of silicate material but it is chemically distinct from tha crust.
The Earth's OUTER CORE ( 2900-5100km) is composed of liquid meterial ( primarily iren and nickel) . The solid INNER CORE ( 5100-6370km) of the earth is made up of iron. It has been discovered that the inner core is rotating and is the cause of Earth's magnetic field.
