1. Crust: The outermost and thinnest layer of the Earth, ranging in thickness from 5 kilometers to 70 kilometers. It is composed of solid rocks and is divided into continental crust (found beneath land masses) and oceanic crust (beneath ocean basins).
2. Mantle: The mantle lies beneath the crust and is composed of hot, dense rock. It extends from the base of the crust to a depth of about 2,900 kilometers. The upper mantle is solid, while the lower mantle is partly molten, allowing slow convection currents that drive plate tectonics.
3. Outer Core: The outer core is located below the mantle and is approximately 2,200 kilometers thick. It is composed primarily of molten iron and some nickel. The movement of the liquid iron in the outer core generates the Earth's magnetic field.
4. Inner Core: The innermost layer of the Earth is the solid inner core, composed mostly of iron and some nickel. It has a radius of about 1,220 kilometers and is extremely dense, contributing significantly to the Earth's overall mass.
5. Transition Mantle (D" Layer): The transition mantle or D'' layer is a region at the lowermost part of the mantle, just above the core-mantle boundary. It exhibits different seismic wave characteristics compared to the rest of the mantle and may represent a distinct compositional or structural boundary.
6. Crust-Mantle Boundary: This boundary separates the crust from the mantle and is marked by a change in rock composition and density. The crust-mantle boundary, also known as the Mohorovicic discontinuity (or Moho), is where seismic waves show a significant increase in velocity.
It's worth noting that some scientists debate the existence of additional layers within the Earth, especially in the mantle, and ongoing research continues to refine our understanding of the Earth's internal structure.
