Natural Processes that Affect Earth’s Land and Oceans

I.  Destructive and Constructive Processes

•     Constructive - Processes that create landforms

•     Destructive - Processes that destroy landforms

II.  Weathering

    A.  Processes that break down rocks at or near the surface of the earth.

    B.  Can be either physical or chemical.

    C.  Cause the surface of the earth to dissolve, decompose, and break into smaller pieces.

    D.  Water is an important cause of weathering.

    E.  Plants cause weathering when roots break apart rock.

    F.  Changes in temperature can break rock, as well as ice forming inside cracks in the rock causing it to break even more.

    G.  Anything that causes rocks to wear down or break apart is a cause of weathering.

III.  Erosion

    A.  The movement of sediments and soil by wind, water, and gravity.

IV.  Deposition

    A.  Dropping, or depositing, of sediments by water, wind, or ice.

    B.  Deposition builds up new land on Earth’s surface.

    C.  Examples:

            1.  Delta at the end of a river

            2.  The pile up of a sand dune in the desert.

            3.  Shells on the beach are deposition by ocean waves.

V.  Landslides

    A.  Mass movements of land due to gravity.

    B.  Landslides can cause buildings to fall, or power and gas lines to break.

    C.  Landslides even occur on the continental slope in the ocean.

VI.  Volcanic Eruptions

    A.  Volcanoes are mountains with openings in Earth’s crust through which magma, gases, and ash reach Earth’s surface.

    B.  When the magma erupts from the volcano the top of the mountain can be changed.

    C.  The lava and ash can destroy forests and bury fields.

    D.  Volcanic eruptions also occur under the oceans; these volcanoes that are built up are called seamounts.

VII.  Earthquakes

    A.  Earthquakes are vibrations on Earth’s surface caused by sudden movement in Earth, often along a fault (a break in Earth’s surface).

    B.  Some earthquakes cause little damage and some cause a lot of damage.

    C.  Large earthquakes can cause landslides.

    D.  Earthquakes under the ocean can cause huge waves, called tsunamis that destroy land and cause great damage if they come ashore.

VIII.  Floods

    A.  Occur when a large amount of water covers land that is usually dry.

    B.  When the flood occurs, rapid erosion can take place and move soil and sediments away.

    C.  When the flood recedes, new sediment is left behind and can build up rich soil deposits.