Composition of the Earth

1. The Composition AND
Structure of the Earth

2. Composition of the Earth
• The Earth is made
up of 3 main layers:
– Core
– Mantle
– Crust
core
Mantle
Crust
• The layers are based on
compound(s) – a
substance composed of
two or more elements

3. The Crust
• The thin and solid outermost layer above the
mantle
• 5 – 100 km thick
• It is the thinnest layer of
the Earth
• Less than 1% of
Earth’s mass
Crust

4. The Crust
Continental Crust
- thicker
- Oxygen, silicon,
aluminum, iron, calcium,
and magnesium
Oceanic Crust
- thinner, but MORE
dense
- Almost twice as
much iron, calcium,
and magnesium

5. The Mantle
• The layer of rock between the crust and the
core
• Much thicker and contains most of the Earth’s
mass; roughly 2/3 or 67%
• The mantle has more magnesium and less
aluminum and silicon than the crust
• It is more dense than the crust

6. The Core
• The central part of the Earth below the mantle
• Scientist believe the Earth’s core is made
mostly of iron and contains smaller amounts
of nickel, but almost no oxygen, silicon,
aluminum, or magnesium
• It makes up roughly 1/3 (33%) of the Earth’s
mass.
• It is more dense than the crust

7. • Layers of the Earth Song!

8. Physical Structure

9. Physical Structure
Lithosphere:
• outermost, solid/rigid layer
• made up of the crust and the rigid upper part of
the mantle
• divided into pieces called tectonic plates
Asthenosphere:
• The soft layer of the mantle on which the
tectonic plates move
• Solid rock that flows very slowly

10. Physical Structure
Mesosphere:
• The strong, lower part of the mantle
• Between the asthenosphere and the outer core
Outer Core:
• Liquid layer of the Earth’s core
• Between the mantle and inner core
Inner Core:
• Solid, dense center of the Earth

11. If you look at a map of the world, you may notice that
some of the continents could fit together like pieces of
a puzzle.

12. Plate Tectonics
• Pieces of the lithosphere that move around on top of
the asthenosphere
• The Earth’s crust is divided into 10-12 major plates
which are moved in various directions.
• This plate motion causes them to collide, pull apart, or
scrape against each other.
• Each type of interaction causes a characteristic set of
Earth structures or “tectonic” features.
• The word, tectonic, refers to the deformation of the
crust as a consequence of plate interaction.

13. World Plates

14. Physical Structure
How do scientists know the inside of the Earth?
• Seismic waves traveling through the Earth
• The waves travel at different speeds due to density
in the layers of the Earth
• Waves travel faster through solids than liquids
• Seismographs measure the waves
• This information can track thickness and density of
each physical layer