Earth & life science PPT for grade 11.

1. EARTH’S INTERNAL HEAT
EARTH AND LIFE SCIENCE

3. THREE LAYERS OF EARTH

4. CRUST
• Thinnest layer of the Earth
• Made up of large amounts of silicon and aluminum
• Composed of plates on which the continents and oceans rest.
These “ride” over molten mantle.
• Crust is part of the lithosphere.
• Two types of Crust: Oceanic and Continental

5. MANTLE
• The Mantle is the largest layer of the Earth at 2900 km thick. The
middle mantle is composed of very hot dense rock that flows like
asphalt under a heavy weight. The movement of the middle
mantle (asthenosphere) is the reason that the crustal plates of
the Earth move.

6. THE OUTER CORE
• Composition: Molten (liquid) metal that is about 4,700°C (8,500°F)
• Thickness: 2,266 km (1,400) miles
• State of Matter: Composed of the melted metals nickel and iron
(liquid)
• Located about 1,800 miles beneath the crust.

7. THE INNER CORE
• Solid sphere made mostly of iron and has Nickel
• It is believed to be as hot as 6,650°C (12,000°F)
• Heat in the core generated by the radioactive decay of uranium
and other elements
• It is solid because of the pressure from the outer core, mantle,
and crust compressing it.
• Thickness: 1271 km (800 miles)

9. SOURCE OF HEAT
PRIMORDIAL HEAT RADIOGENIC HEAT

10. PRIMORDIAL HEAT
• During the early formation of the
Earth, the internal heat energy that
gradually gathered together by
means of dispersion in the planet
during its few million years of
evolution.
• Accretional energy – the energy
deposited during the early
formation of a planet. The core is a
storage of primordial heat that
originates from times of accretion
when kinetic energy of colliding
particles was transformed into
thermal energy.

11. RADIOGENIC HEAT
• The thermal energy released as a
result of spontaneous nuclear
disintegration.
• It involves the disintegration of
natural radioactive elements
inside the earth – like Uranium,
Thorium and Potassium. Uranium
is a special kind of element
because when it decays, heat
(radiogenic) is produced.
• Without the process of
radioactive decay, there would be
fewer volcanoes and earthquakes
– and less formation of earth’s
vast mountain ranges.

12. HEAT TRANSFER
CONVECTION CONDUCTION RADIATION

13. CONDUCTION
Conduction carries heat
from the Earth's core and
radiation from the Sun to
the Earth's surface. When
the atmosphere in normal
temperature contacts
with the warm surfaces of
the land, it transfer
thermal energy, then it
will heats up the rest of
the air through
convection.

14. CONVECTION
• The transfer of heat by the
movement of mass, and it is a
more effective mode of heat
transport in the Earth than
pure conduction. Convection
dominates the thermal
conditions in zones with
significant amounts of fluids
(molten rocks) and thus
governs the heat transport in
the fluid outer core and the
mantle.
• This results to the movement
of tectonic plates.

15. RADIATION
• The least important
mode of heat transport
in the Earth. The
process of heat
exchange between the
Sun and the Earth,
through radiation,
controls the
temperatures at the
Earth's surface.