The document summarizes the structure and composition of the Earth's main layers. It is composed of three main layers from outer to inner: the crust, mantle, and core. The crust is the outermost solid rock layer that varies between 5-70km thick and is made of either continental or oceanic crust. Below is the mantle that extends 2,890km deep and slowly circulates material. At the center is the core, divided into a solid inner core and liquid outer core, with temperatures over 6,000°C.

2. Topic
The Structure of the Earth
Presented To: Sir Shahroz Khan
Presented By: Abdul Qahar
&
Naveed Akhtar

3. Structure of the Earth
• The Earth is made up of
3 main layers:
– Core
– Mantle
– Crust
Inner core
Outer core
Mantle
Crust
The interior structure of the Earth is layered in spherical
shells, like an onion.

4. Structure
• The structure of Earth can be defined in two ways:
1. Mechanical properties such as rheology,
2. Chemically.
• 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.

5. Depth
LayerKilometres Miles
0–35 0–22
Crust (locally varies
between 5 and 70 km)
35–60 22–37
Uppermost part of
mantle
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
Physical Description

6. 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)

7. Core
• 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.

8. 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
in the
outer core and 12,600–13,000 kg/m3
in the inner core.

9. Mantle
• 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
Earth.
• The pressure at the bottom of the mantle is ~140 GPa
(1.4 Matm).

10. Mantle
• 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.

11. Mantle composition
• 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.

12. The Crust
• This is where we live!
• The Earth’s crust is made of:
1. Continental Crust
2. Oceanic Crust

13. Continental crust
• The thicker crust is continental crust, which is
less dense and composed of (felsic) sodium
potassium aluminium silicate rocks, like
granite.

14. Oceanic crust
• 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.

15. Crust
• The crust ranges from 5–70 km (~3–44 miles)
in depth and is the outermost layer.