The Structure of the Earth
Presented To: Sir Shahroz Khan
Presented By: Abdul Qahar
Structure of the Earth
• The Earth is made up of
3 main layers:
The interior structure of the Earth is layered in spherical
shells, like an onion.
• The structure of Earth can be defined in two ways:
1. Mechanical properties such as rheology,
• Mechanically, it can be divided into lithosphere,
asthenosphere, mesospheric mantle, outer core, and
the inner core.
• Chemically, Earth can be divided into the crust, upper
mantle, lower mantle, outer core, and inner core.
Crust (locally varies
between 5 and 70 km)
Uppermost part of
35–2,890 22–1,790 Mantle
2,890–5,150 1,790–3,160 Outer core
5,150–6,360 3,160–3,954 Inner core
• Discovered in 1936 by Inge Lehmann.
• Temperature is 6,000 degrees Celsius (10,832 F).
• Outer core: 1,380 miles (2,200 kilometers)
• Inner core: 780 miles (1,300 kilometers)
• The INNER Core - is solid (because of EXTREME pressure
from everything above it)
• The core is thus believed to largely be composed of iron
(80%), along with nickel and one or more light elements,
whereas other dense elements, such as lead and uranium.
Seismic measurements of core
• Core is divided into two parts:
• “Solid" inner core with a radius of ~1,220 km
• Liquid outer core radius of ~3,400 km.
• Densities are B/W 9,900 and 12,200 kg/m3
outer core and 12,600–13,000 kg/m3
in the inner core.
• Temperatures is B/W 500 to 900 °C (932 to 1,652 °F)
at the upper boundary with the crust; to over 4,000 °C
(7,230 °F) at the boundary with the core.
• Depth is 2,890 km, making it the thickest layer of
• The pressure at the bottom of the mantle is ~140 GPa
• Because of the temperature difference between the
Earth's surface and outer core and the ability of the
crystalline rocks at high pressure and temperature to
undergo slow, creeping, viscous-like deformation
over millions of years, there is a convective material
circulation in the mantle.
• It has all the properties of a SOLID but can
flow very slowly just beneath the crust.
• Here it is made of MAGMA – very thick and
sticky molten rock.
• The mantle is composed of silicate rocks that
are rich in iron and magnesium.
• This is where we live!
• The Earth’s crust is made of:
1. Continental Crust
2. Oceanic Crust
• The thicker crust is continental crust, which is
less dense and composed of (felsic) sodium
potassium aluminium silicate rocks, like
• The thin parts are the oceanic crust, which
underlie the ocean basins (5–10 km) and are
composed of dense (mafic) iron magnesium
silicate igneous rocks, like basalt.
• The crust ranges from 5–70 km (~3–44 miles)
in depth and is the outermost layer.