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1. UNIT 7
WHAT IS THE EARTH MADE OF?
LIITHOSPHERE AND HYDROSPHERE

2. The internal structure of the Earth
Core: deepest part. Part solid,
part liquid.
Mantle: around the core. Magma
(molten rock).
Crust: Outer layer of the Earth.
Solid rock.
When thicker  Continents.
When thinner  Under the
oceans.
1. THE STRUCTURE OF THE EARTH

3. The external structure
of the Earth
Lithosphere: solid,
rocky layer. Formed by
the crust and the
upper mantle.
Hydrosphere: water,
mostly liquid.
Atmosphere: gas.

4. 2. THE FORMATION OF THE RELIEF: INTERNAL AND EXTERNAL FORCES
Lithos + sphere.
Crust and upper mantle of the Earth.
Different geographical features  RELIEF

5. Tectonic plates
Formation of
the continents
and the ocean
floor.
2.1 - INTERNAL
FORCES: TECTONIC
PLATES AND
THEIR
MOVEMENTS

7. CONTINENTS  Some of the tectonic plates formed the continents (def. enormous
landmasses separated by oceans).

8. Asia: largest continent of the Earth.
Surrounded by:
North  Arctic Ocean.
South  Indian Ocean.
East  Pacific Ocean.
West  Europe and Africa.

9. America: 2nd largest. Longest
continent from north to south.
Between the Atlantic and Pacific
oceans.
Arctic Ocean in the north, and
Antarctic in the south.
Divided in three subcontinents:
North America.
Isthmus of Central America.
South America.

10. Africa:
Surrounded by:
North  Mediterranean Sea.
South  Antarctic Ocean.
East  Indian Ocean and Asia.
West  Atlantic Ocean.

11.  Antarctica:
o Southern part of the
Earth.
 Surrounded by the
Antarctic Ocean,
the Pacific, Atlantic
and Indian oceans.

12. Europe:
Western part of the
Eurasian plate.
Surrounded by:
North  Arctic Ocean.
South 
Mediterranean Sea.
East  Asia (Ural
Mountains, Caspian
Sea, Caucasus and
Black Sea).
West  Atlantic
Ocean.

13. Oceania:
Around 10 thousand
islands in the Pacific
Ocean.
Four areas:
Australasia,
Melanesia,
Micronesia and
Polynesia.

14. Weathering
Breaking down
of the rock due
to the
combination of
water and
atmospherical
conditions
(mostly heat and
cold)
2.2 - EXTERNAL
FORCES OF THE
EARTH: THE
SHAPING OF THE
RELIEF
WATER
Main agent acting on the relief.
Different types of effects

15. Erosion
Removal of
material.

16. Fluvial erosion

17. Coastal erosion

18. Coastal
erosion

19. Sedimentation
Deposition of
material
brought by the
water.

21. Cape Cod
(Massachusetts)

22. History of
sedimentation in
Barcelona.
Barceloneta beach

23. Ebro delta
Mississippi delta

24. Dissolution
(Karst)

26. WIND
Erosion
Small particles: sand
and dust.
Mostly in dry areas.

29. Sedimentation

30. HUMAN BEINGS

31. Combination of
internal and external
forces
3. ELEMENTS OF THE RELIEF

32. 3.1. CONTINENTAL LANDFORMS
Mostly formed by the combination of
internal forces and continental waters,
rain and wind.

35. 3.2. COASTAL LANDFORMS
Mostly formed by the
action of marine
waters and the land.

49. 3.3. SUBMARINE RELIEF

53. 4. THE HYDROSPHERE: WATER ON EARTH

55. 4.1. MARINE WATERS
Marine waters experience the following:
• Waves: undulated movement of the water caused by the pressure of wind on its surface.

56. • Tides: periodic changes in the level of the water caused by the gravitational pull of
the Sun and the Moon.

59. • Currents: circular
patterns or hot or cold
waters in movements.
They have a great effect
on the climate of the
different places of the
world.

61. 4.2. Fresh waters: Continental waters
Only a 3 % of the water of the Earth.
It can be found:
• Liquid: rivers, lakes and underground deposits.
• Rivers: continuous current of fresh water.
• Lakes: inland bodies of still water.
• Solid: glaciers and icebergs.
• Most of the fresh water of the Earth
• Glaciers: large bodies of ice that cover polar
regions and some mountain summits.
• Gas: in the atmosphere.

62. 5. GEOLOGICAL HAZARDS AND PROBLEMS RELATED WITH WATER

63. 5.1. GEOLOGICAL HAZARDS
Related with the movements of the plate tectonics and the pressure of gasses to the crust.
EARTHQUAKES
Result of seismic waves, or vibrations caused by the movement of tectonic plates.
- Waves  Spread in all directions (concentrically)
- As they happen, the land shakes  Devastating effects.

66. VOLCANOES
A crack in the crust reaches an area of magma (molten rock), and because of the pressures of
the interior of the Earth, the magma is brought to the surface of the Earth.

67. Crater  Where the magma comes out
(lava)
Cone  Formed by the solidification of
materials from eruptions (gasses, ashes,
rocks and lava). They may form mountains
and islands.

69. 5.2. Problems related with water
Water is of the utmost importance for life in the planet, and for humans in particular. Oceans,
seas, rivers and lakes have been an essential factor to human development and history. The
waters have been used for all sorts of economic activities, from their use for irrigation in
agriculture to their importance for tourism. Among the main uses of both marine and fresh
waters for humanity we find:
 Agriculture.
 Fishing.
 Navigation.
 Mining (salt, for example).
 Energy production.
 Leisure (tourism).
 Sports.

71. Problems associated with water.
 Scarcity: it occurs when there is little precipitation or when humans overuse the available
water.

74.  Flood disasters: mostly when unexpected, they can be very dangerous.

75.  Pollution: the misuse of water resources, combined with the spills of different sort of
elements may alter the biosphere and even be toxic.