1. Crust:

* State: Solid (primarily igneous rock, but also sedimentary and metamorphic rock)

* Composition: Silicon, oxygen, aluminum, iron, calcium, sodium, potassium, and magnesium.

* Notable Features: The crust is Earth's outermost layer and is relatively thin compared to the other layers. It's divided into oceanic crust (thinner and denser) and continental crust (thicker and less dense).

2. Mantle:

* State: Solid (but behaves like a very viscous fluid over long periods due to intense heat and pressure)

* Composition: Mostly silicate minerals (like olivine and pyroxene) with smaller amounts of iron, magnesium, calcium, and aluminum.

* Notable Features: The mantle makes up the majority of Earth's volume. It's divided into the upper mantle (which includes the asthenosphere, a partially molten layer) and the lower mantle.

3. Outer Core:

* State: Liquid (molten iron and nickel)

* Composition: Iron (approximately 88%), nickel (approximately 5.5%), with smaller amounts of sulfur, silicon, and oxygen.

* Notable Features: The outer core's movement generates Earth's magnetic field.

4. Inner Core:

* State: Solid (due to immense pressure)

* Composition: Primarily iron with a smaller amount of nickel.

* Notable Features: The inner core is extremely hot, but the intense pressure prevents it from becoming liquid.

Important Note: The boundaries between Earth's layers aren't sharp lines. They are zones of transition where the composition and properties of the materials gradually change.