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THE EARTH’S RELIEF



        SOCIAL SCIENCES
        1º ESO
1. THE STRUCTURE OF THE
EARTH

   The Earth is divided into layers:
    –   The crust is the surface layer. It is a thin, solid
        layer made of rock. The Earth’s crust has a solid
        part (continents), and a liquid part (oceans).
    –   The mantle is the intermediate layer. This layer is
        almost 85 % of the Earth’s volume. It includes
        magma, which is molten rock.
    –   The core is the deepest layer.
The internal structure of the Earth
1. THE STRUCTURE OF THE
EARTH

   The Earth’s temperature increases with depth.
    The temperature in the core reaches about
    4.500 ºc.
2. WHAT IS THE EARTH´S RELIEF
LIKE?

   The Earth’s relief is
    diverse: mountains,
    plateaux, plains,
    depressions,
    continental shelves,
    deep-sea trenches,
    oceanic ridges, etc.
3. HOW IS THE RELIEF FORMED?

   The Earth’s relief changes.
   In 1912 the German Alfred Wegener outlined
    his continental drift theory. According to
    this theory 200 millions years ago there was
    a single giant land mass (one
    supercontinent), called Pangaea. This
    Pangaea was surrounded by a single ocean,
    called Tethys Sea.
Pangaea, 200 millions years ago
Pangaea evolution

   The Pangaea broke up,
    forming the continents.
    These continents are
    no fixed, but they are
    moving, because the
    crust (the Earth’s layer
    where we live) is
    divided into several
    plates, called tectonic
    plates.
Pangaea evolution
Tectonic plates

   These plates are not
    fixed, but they are
    moving slowly over
    the mantle. When a
    plate collides with
    another one,
    earthquakes and
    eruptions of volcanoes
    are caused.
Distribution of the tectonic plates
   The most
    important
    tectonic plates
    in the world
    are the
    Eurasian
    plate, the
    African plate,
    the North
    American and
    South
    American
    plates, the
    Pacific plate,
    the Indo-
    Australian
    plate, etc.
4. CONTINENTS AND OCEANS

   On the earth’s crust there are emergent and
    submerged lands:
    –   Continents. Continents occupy 30% of the land
        surface and are surrounded by oceans and seas.
        There are six continents: Asia, America, Africa,
        Antarctica, Europe and Oceania. Most of the
        emerged land is in the northern hemisphere.
The Continents
Oceans

 –   Oceans. Oceans are large masses of salt water.
     There are five oceans: The Pacific Ocean, The
     Atlantic Ocean, The Indian Ocean, The Arctic
     Ocean and the Southern Ocean. Most oceans are
     in the southern hemisphere.
The Oceans
5. LAND RELIEF

   Continental relief
    –   The Earth’s surface isn’t flat, there are
        mountains, plains, plateaux, valleys, etc. The
        relief of the continents is very varied.
5. LAND RELIEF

 –   The relief is the result of the internal forces of
     the Earth (plate movements, volcanoes,
     earthquakes, etc.) and external agents (wind,
     rain, temperatures, rivers, groundwater, lakes,
     ice... and human-beings). The internal forces
     are responsible for the origin and the
     elevation of topography and external agents
     cause the erosion and modeling of the Earth’s
     relief.
5. LAND RELIEF

   The main forms of continental relief are:
    –   Mountains. A mountain is a land mass that rises high
        above the area around it. There are ranges of mountains
        that are higher and larger than others. The largest ranges of
        mountains are called ridges.
    –   Plains. Plains are large flats tracts of land.
    –   Plateaux. Plateaux are large areas of high land. They are
        high well above sea level. They are higher than plains.
    –   Valleys. They are sunken land and are surrounded by
        mountains or ridges. In valleys rivers may flow.
Main forms of continental relief
5. LAND RELIEF

   Continental waters
    –   Continental waters are: rivers, glaciers,
        groundwaters, lakes and inner seas.
Rivers

   A river is a natural stream of
    water that flows in a channel.
    The flow is the amount of water
    that the river carries. Rivers are
    fed by overland runoff,
    groundwater seepage, and
    meltwater released along the
    edges of snowfields and
    glaciers. Direct precipitation only
    provides very small amounts of
    water.
Rivers

   The mouth is where the river flows into the
    sea. It can be:
    –   A delta: Low-lying plain composed of stream-
        borne sediments deposited by a river at its mouth.
    –   An estuary: A flow of water in a channel like a
        small river.
Rivers
     –   Delta




     –   Estuary
Glaciers

   A glacier is a large mass of ice that forms
    on land through the recrystallization of snow
    and that moves forward under its own weight.
Groundwaters

   Groundwaters are water that occurs below
    the surface of the Earth.
Lakes

   Lakes are standing waters that occupy an
    inland basin.
5. LAND RELIEF

   Coast relief and ocean bed relief
    –   The coast is a broad area of land that borders
        the sea. Among the different types of coast relief
        we have to find beaches, gulfs, cliffs and capes.
    –   On the ocean bed relief there is the continental
        platform, continental bank, abysmal, dorsal
        oceanic plain and ocean basin.
Coast relief
Ocean bed relief




           magma
6. NATURAL RISKS

   The displacement of the plates also gives
    rise to other phenomena: volcanoes and
    seisms or earthquakes.
What is a volcano?

   A volcano is a huge
    eruption of ash, smelly
    gases, and melted rock
    below the earth. A
    volcano forms above the
    ground. However no
    eruption of a volcano is a
    single event. Along with
    an eruption, comes major
    destruction.
Volcano
What is an earthquake?

   An earthquake is a shaking of the
    ground caused by the sudden
    breaking and movement of large
    sections (tectonic plates) of the
    earth’s rocky outermost crust. The
    edges of the tectonic plates are
    marked by faults (or fractures).
    Most earthquakes occur along the
    fault lines when the plates slide
    past each other or collide against
    each other.

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The Earth’s Relief

  • 1. THE EARTH’S RELIEF SOCIAL SCIENCES 1º ESO
  • 2. 1. THE STRUCTURE OF THE EARTH  The Earth is divided into layers: – The crust is the surface layer. It is a thin, solid layer made of rock. The Earth’s crust has a solid part (continents), and a liquid part (oceans). – The mantle is the intermediate layer. This layer is almost 85 % of the Earth’s volume. It includes magma, which is molten rock. – The core is the deepest layer.
  • 3. The internal structure of the Earth
  • 4. 1. THE STRUCTURE OF THE EARTH  The Earth’s temperature increases with depth. The temperature in the core reaches about 4.500 ºc.
  • 5. 2. WHAT IS THE EARTH´S RELIEF LIKE?  The Earth’s relief is diverse: mountains, plateaux, plains, depressions, continental shelves, deep-sea trenches, oceanic ridges, etc.
  • 6. 3. HOW IS THE RELIEF FORMED?  The Earth’s relief changes.  In 1912 the German Alfred Wegener outlined his continental drift theory. According to this theory 200 millions years ago there was a single giant land mass (one supercontinent), called Pangaea. This Pangaea was surrounded by a single ocean, called Tethys Sea.
  • 8. Pangaea evolution  The Pangaea broke up, forming the continents. These continents are no fixed, but they are moving, because the crust (the Earth’s layer where we live) is divided into several plates, called tectonic plates.
  • 10. Tectonic plates  These plates are not fixed, but they are moving slowly over the mantle. When a plate collides with another one, earthquakes and eruptions of volcanoes are caused.
  • 11. Distribution of the tectonic plates  The most important tectonic plates in the world are the Eurasian plate, the African plate, the North American and South American plates, the Pacific plate, the Indo- Australian plate, etc.
  • 12. 4. CONTINENTS AND OCEANS  On the earth’s crust there are emergent and submerged lands: – Continents. Continents occupy 30% of the land surface and are surrounded by oceans and seas. There are six continents: Asia, America, Africa, Antarctica, Europe and Oceania. Most of the emerged land is in the northern hemisphere.
  • 14. Oceans – Oceans. Oceans are large masses of salt water. There are five oceans: The Pacific Ocean, The Atlantic Ocean, The Indian Ocean, The Arctic Ocean and the Southern Ocean. Most oceans are in the southern hemisphere.
  • 16. 5. LAND RELIEF  Continental relief – The Earth’s surface isn’t flat, there are mountains, plains, plateaux, valleys, etc. The relief of the continents is very varied.
  • 17. 5. LAND RELIEF – The relief is the result of the internal forces of the Earth (plate movements, volcanoes, earthquakes, etc.) and external agents (wind, rain, temperatures, rivers, groundwater, lakes, ice... and human-beings). The internal forces are responsible for the origin and the elevation of topography and external agents cause the erosion and modeling of the Earth’s relief.
  • 18. 5. LAND RELIEF  The main forms of continental relief are: – Mountains. A mountain is a land mass that rises high above the area around it. There are ranges of mountains that are higher and larger than others. The largest ranges of mountains are called ridges. – Plains. Plains are large flats tracts of land. – Plateaux. Plateaux are large areas of high land. They are high well above sea level. They are higher than plains. – Valleys. They are sunken land and are surrounded by mountains or ridges. In valleys rivers may flow.
  • 19. Main forms of continental relief
  • 20. 5. LAND RELIEF  Continental waters – Continental waters are: rivers, glaciers, groundwaters, lakes and inner seas.
  • 21. Rivers  A river is a natural stream of water that flows in a channel. The flow is the amount of water that the river carries. Rivers are fed by overland runoff, groundwater seepage, and meltwater released along the edges of snowfields and glaciers. Direct precipitation only provides very small amounts of water.
  • 22. Rivers  The mouth is where the river flows into the sea. It can be: – A delta: Low-lying plain composed of stream- borne sediments deposited by a river at its mouth. – An estuary: A flow of water in a channel like a small river.
  • 23. Rivers – Delta – Estuary
  • 24. Glaciers  A glacier is a large mass of ice that forms on land through the recrystallization of snow and that moves forward under its own weight.
  • 25. Groundwaters  Groundwaters are water that occurs below the surface of the Earth.
  • 26. Lakes  Lakes are standing waters that occupy an inland basin.
  • 27. 5. LAND RELIEF  Coast relief and ocean bed relief – The coast is a broad area of land that borders the sea. Among the different types of coast relief we have to find beaches, gulfs, cliffs and capes. – On the ocean bed relief there is the continental platform, continental bank, abysmal, dorsal oceanic plain and ocean basin.
  • 30. 6. NATURAL RISKS  The displacement of the plates also gives rise to other phenomena: volcanoes and seisms or earthquakes.
  • 31. What is a volcano?  A volcano is a huge eruption of ash, smelly gases, and melted rock below the earth. A volcano forms above the ground. However no eruption of a volcano is a single event. Along with an eruption, comes major destruction.
  • 33. What is an earthquake?  An earthquake is a shaking of the ground caused by the sudden breaking and movement of large sections (tectonic plates) of the earth’s rocky outermost crust. The edges of the tectonic plates are marked by faults (or fractures). Most earthquakes occur along the fault lines when the plates slide past each other or collide against each other.