The earth is composed of three main layers: the crust, mantle, and core. The crust makes up less than 1% of the earth's mass and is the thinnest layer. Underneath is the mantle, which comprises most of the earth's mass and volume. The mantle originates magma and is divided into upper and lower sections. At the center is the core, with a solid inner core surrounded by a liquid outer core.

1. Earth’s Layers
The earth is composed of three main layers: the crust, the mantle, and the core.
The crust is the outer layer of the earth, made up of igneous, sedimentary, and
metamorphic rock. It is very thin relative to the size of the entire earth. From the
top of the mountains to the oceans’ floors, the crust is at most 70 km thick and
makes up less than 1% of the earth’s mass. The crust is divided into two sections:
the continental crust with thick sedimentary and metamorphic rocks, and the
oceanic crust, which has only a thin layer of sediments.
Under the crust is the mantle; this is the area of the earth where magma
originates, as the source of igneous rocks. The mantle makes up the majority of
the earth; it is about 2900 km thick, and makes up about 70% of the earth’s mass.
The mantle is composed of silicon, oxygen, aluminum, and iron.
The core is found at the centre of the earth and is estimated to have a
temperature of 6000°C. It is divided into two sections: the outer core and the
inner core. Together they make up about 30% of the earth’s mass, with a thickness
of about 3500 km. The inner core is a solid iron-nickel ball; the outer core is a
thick liquid mixture of iron and sulphur.
Geophysics, which studies the physics of the Earth, has led to many significant discoveries
about the Earth and its make-up. Seismologic studies of the Earth have uncovered new
information about the interior of the Earth that has helped to give credence to plate tectonic
theory.
Geophysical studies have revealed that the Earth has several distinct layers. Each of these
layers has its own properties. The outermost layer of the Earth is the crust. This comprises
the continents and ocean basins. The crust has a variable thickness, being 35-70 km thick
in the continents and 5-10 km thick in the ocean basins. The crust is composed mainly of
alumino-silicates.
The next layer is the mantle, which is composed mainly of ferro-magnesium silicates. It is
about 2900 km thick, and is separated into the upper and lower mantle. This is where most
of the internal heat of the Earth is located. Large convective cells in the mantle circulate
heat and may drive plate tectonic processes.

2. The last layer is the core, which is separated into the liquid outer core and the solid inner
core. The outer core is 2300 km thick and the inner core is 1200 km thick. The outer core is
composed mainly of a nickel-iron alloy, while the inner core is almost entirely composed of
iron. Earth's magnetic field is believed to be controlled by the liquid outer core.