Landforms and Oceans

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Landforms and Oceans Support Document

Natural Processes 5-3.1

I. Natural Processes

·  Events of nature that happen causing changes to Earth’s land and oceans are called Natural Processes.

·  These changes can result in either creating landforms or destroying landforms.

·  Processes that create landforms are called constructive.

·  Processes that destroy landforms are called destructive.

·  Examples of destructive processes are: weathering, erosion, landslides, earthquakes, volcanic eruptions, and floods. These are discussed below.

·  Examples of constructive processes are: deposition, volcanic eruptions, landslides, and floods. These are discussed below.

II. Weathering; Destructive

·  Weathering is anything that causes rocks to wear down or break apart into smaller pieces at or near the Earth’s surface. (Weathering = Break)

·  There are two categories of weathering: physical weathering and chemical weathering.

·  These processes cause the surface of the Earth to dissolve, decompose and break into smaller pieces.

·  Causes of weathering:

-  Water; important cause of weathering.

-  Plants ; when roots break apart rock

-  Temperature changes; causes rock to break

-  Ice; forms inside of cracks in rocks causing it to break even more.

-  Anything else that causes rock to wear down or break.

III. Erosion; Destructive

·  Erosion is the movement of sediments (pieces of earth) and soil. (Erosion = Movement)

·  Effect of deposition

- Movement of sediments and soil

·  Causes of erosion:

-  wind

-  water

-  gravity

-  ice

IV. Landslides; Destructive/Constructive

·  Landslides are mass movements of land due to gravity. (Landslide = mass movement)

·  Effect of landslides

-  buildings fall

-  power lines break

-  gas lines break

·  Cause of landslides

- Gravity

- Even occur on the continental slope in the ocean.

V. Earthquakes; Destructive

·  Earthquakes are vibrations on Earth’s surface caused by sudden movement in Earth.

·  Effects of earthquakes

-  Sometimes little damage is done/sometimes a lot of damage.

-  landslides (if a large earthquake)

-  Tsunamis or HUGE waves (if earthquake is under the ocean) that destroy land and cause great damage if they come ashore.

·  Causes of earthquakes

-  sudden movement in earth

-  faults ( a break in Earth’s surface) – these often cause the sudden movement

VI. Floods; Constructive and Destructive

·  Floods occur when a large amount of water covers land that is usually dry.

·  Effect of floods

-  rapid erosion, moving soil and sediments away (destructive)

-  rich soil deposits left behind when flood recedes (constructive)

·  Cause of flooding

VII. Deposition; Constructive

·  Deposition is the dropping, or depositing of sediments. (Deposition = Dropping / Building up)

·  Effect of deposition

- New land building up on Earth’s surface

·  Causes of deposition

-  Water; ex: shells on the beach are deposition by ocean waves or delta at the end of a river.

-  Wind ; ex: sand dunes on the desert & beach are deposition by wind

-  Ice : ex: glaciers push debris as they slide, causing it to build up

VIII. Volcanic Eruptions; Constructive/Destructive

·  Volcanoes are mountains with openings in Earth’s crust

·  Seamounts are volcanoes that are built up under the ocean- if it rises above ocean surface it causes seamounts ex: Japan, Hawaii

·  Volcanic Eruptions occur when magma, gases, and ash reach Earth’s surface.

·  Effect of volcanic eruptions

-  Changes in Earth’s surface

-  changes in top of the mountain (volcano)-

Constructive- top built up

Destructive- exploded off

-  lava and ash can destroy forests and bury fields

-  can cause changes in weather patterns

·  Under the ocean