Constructive and Destructive Forces that effect Earth’s Landforms.

Constructive and Constructive and Destructive Forces Destructive Forces

that effect Earth’s that effect Earth’s LandformsLandforms

WeatheringWeatheringWeathering is the process that Weathering is the process that breaks down breaks down

rocks at or near the surface of the earth. rocks at or near the surface of the earth. Weathering can be either physical or

chemical. These processes cause the surface of the

earth to dissolve, decompose, and break into smaller pieces.

Weathering Weathering cont….cont….Water is an important cause of weathering. Plants cause weathering when roots break apart

rock. (physical) Changes in temperature can break rock, as well as

ice forming inside cracks in the rock causing it to break even more.

Anything that causes rocks to wear down or break

apart is a cause of weatheringweathering.

ErosionErosion•Erosion is the movementmovement of sediments and soil by wind,

water, ice, and gravity.

DepositionDepositionDeposition is the dropping, or depositing, of sediments (soil, sand and minerals) by water,

wind, or ice. Deposition builds up new land on Earth’s surface,

like a delta at the end of a river or the pile up of a sand dune in the desert.

Shells on the beach are deposition by ocean waves.

FORCESFORCES

Constructive Constructive

• Processes that create landforms (deposition,

landslides, volcanic eruptions, floods)

DestructiveDestructive• Processes that destroy

landforms (weathering, erosion, landslides, volcanic eruptions,

earthquakes, floods)

EarthquakesEarthquakesEarthquakes are vibrations on Earth’s surface caused

by sudden movement in Earth, often along a fault, a break in Earth’s surface.

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

Large earthquakes can cause landslides.

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

Tsunami

EarthquakesEarthquakes

These earthquakes created faults.

Who can tell me what a fault is?

Volcanic eruptionsVolcanic eruptions•Volcanoes are mountains with openings in Earth’s crust through which magma, gases, and ash reach Earth’s surface. •Volcanoes can change Earth’s surface. •When the magma erupts from the volcano the top of the mountain can be changed, either built up or exploded off. •The lava and ash can destroy forests and bury fields.

Volcanoes cont…Volcanoes cont…•Volcanic eruptions can even change Earth’s weather patterns. •Volcanic eruptions also occur under the oceans; these volcanoes that are built up are called seamounts. •If the seamount rises above the ocean surface it is called a volcanic island (for example Hawaii or Japan).

Cooled magma creates solid landmasses

LandslidesLandslidesLandslides are mass movements of land due to

gravity. Landslides can cause buildings to fall, or power

and gas lines to break. Landslides even occur on the continental slope in

the ocean.

TsunamisTsunamisSometimes giant sea waves, called

tsunamis, are caused by underwater earthquakes, volcanic eruptions, or landslides.

FloodsFloodsFloods occur when a large amount of water

covers land that is usually dry. When the flood occurs, rapid erosion can take place

and move soil and sediments away. When the flood recedes (goes away), new sediment

(dirt) is left behind and can build up rich soil deposits.

Constructive vs. Constructive vs. DestructiveDestructiveConstructive

Processes that create

landforms

Destructive Processes that

destroy landforms

EXAMPLES: *Deposition

*Landslides *volcanic eruptions *Floods

EXAMPLES: *Weathering

*Erosion *Landslides

*Volcanic eruptions *Earthquakes

*Floods

Deposition is a process that…

A. Dissolves sedimentB. Breaks down rock to form

sedimentC. Removes sediment from

landformsD. Drops sediment to form

landforms

Where do deltas form?

A. In desert areasB. At river mouthsC. On the banks of riversD. In valleys formed by glaciers

A. deposition of sediment – a destructive force B. deposition of sediment – a constructive force C. erosion – a destructive force D. erosion – a constructive force

A river overflows due to excessive rains, and floods A river overflows due to excessive rains, and floods surrounding areas. After the rain stops, the water surrounding areas. After the rain stops, the water returns to the river’s original path. However, the returns to the river’s original path. However, the surrounding land is now covered with new soil. This is surrounding land is now covered with new soil. This is an example of….an example of….

Volcanoes can create new land when they release…

A. LavaB. WaterC. GasD. Mud

What is weathering?

A. A type of climateB. The transport of sedimentC. The breakdown of rockD. The aging of rock

Tsunamis are caused by…A. hurricanes B. a very large high tide C. underwater earthquakes D. the migration of whales

How do earthquakes change the land?

A. They transport sediment.B. They form cracks in the surface.C. They release ash and lava.D. They cause chemical weathering.

Which is an example of deposition?A. acids that eat into rockB. wind building up sand dunes C. rivers wearing down mountains

D. plant roots breaking apart rock

Which is Which is notnot a type of physical a type of physical weathering? weathering?

A. Roots breaking rockB. Ice Breaking rockC. Wind and waterD. Chemical Changes

What does erosion do?

A. breaks down rock physicallyB. moves broken pieces of rockC. changes rock chemicallyD. change sediment into rock