The earth

 The Earth's structure is made up of three main layers: the crust, the mantle, and the core: 

Crust

The outermost layer, made of solid rock like basalt and granite. The crust is brittle and the thinnest layer. There are two types of crust: oceanic and continental. 

Mantle

The thickest layer, made of hot, dense, iron and magnesium-rich solid rock. The mantle is semi-solid and slowly moves in a convection style. 

Core

The innermost layer, made of an outer core of liquid iron and an inner core of solid iron. The inner core is the hottest layer of the Earth, with temperatures up to 5,500°C. 

The Earth's layers were formed when gravity pulled the densest materials to the center of the Earth. The crust is made of the lightest materials, while the core is made of heavy metals like nickel and iron. 

The movement of tectonic plates, which are pieces of the lithosphere (the crust and upper mantle), causes earthquakes, volcanoes, and other seismic activity in the crust.