In this presentation you will:

Natural Forces

see the changes to the Earth’s surface caused by wind, water and ice Next >

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deltas

Landforms

A landform is the name given to the way different parts of the Earth’s surface appear, for example:

canyons

sand dunes

Changes to Landforms

Landforms sometimes change very quickly.

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Sometimes they change more slowly.

Changes to Landforms

Volcanoes and earthquakes can alter the shape of the Earth’s surface in a few moments.

Weathering and erosion are much slower ways that give us our landscape.

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Weathering

Weathering is usually a slow change. It breaks rocks apart and changes landscape.

After years of freezing and thawing, rocks break apart. Next >

If water gets into a crack in a rock and then freezes, it expands. It can then cause larger cracks.

Weathering

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Heat from the Sun can cause weathering.

The Sun dries the rocks, making some more easily turn to sand.

Erosion

Erosion most often happens slowly.

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Erosion is when wind, water and ice carry away small rocks, soil, sand and dust.

Erosion

Large amounts of falling rocks, mud or snow can erode the Earth’s surface much more quickly.

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Erosion

Wind and flowing water are most often linked to erosion.

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Glaciers however, are terrifically powerful at causing erosion.

Erosion

The frozen water in a glacier moves extremely slowly, but can carve a vast valley.

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Glaciers deposit huge amounts of rock, called moraine, where they melt.

What happens naturally to water to make cracks in rocks and break them up?

Question 1

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A) It boils

B) It evaporates

C) It freezes

D) It melts

What happens naturally to water to make cracks in rocks and break them up?

Question 1

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A) It boils

B) It evaporates

C) It freezes

D) It melts

What is the name used to describe wind, water and ice carrying away small rocks, soil, and sand?

Question 2

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A) Weathering

B) Erosion

C) Evaporation

D) Climate change

What is the name used to describe wind, water and ice carrying away small rocks, soil, and sand?

Question 2

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A) Weathering

B) Erosion

C) Evaporation

D) Climate change

Canyons

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The water carries away bits of weathered rock and sand, and the river bed sinks lower.

Canyons are formed by the water moving in a river.

Canyons

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Where the river flows quickly, rock and sand in the water erodes the river walls.

Erosion over hundreds of thousands of years drives the river deeper and deeper.

Deltas

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A delta is formed when a river flows into the sea or into a lake.

A river carries the results of weathering and erosion downstream.

These are the rocks, soil and sand that have fallen into the river, or have been scraped from the river walls.

Deltas

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When the river nears the sea, it slows.

The level of the river bed rises. The flow slows further, and even more sediment is deposited.

The rocks, soil and sand that the river is carrying, is called sediment. This drops to the river bed.

Deltas

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Over hundreds of years, the sediment spreads out to form new land areas.

As the new land areas form, streams start running on new routes to the sea.

Deltas

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Deltas make excellent farmland because sediment is rich in minerals and fresh water is always nearby.

Sand Dunes

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Dunes are large quantities of sand that have been piled up by the wind.

The wind blows the sand along the ground, or carries it in the air.

Sand Dunes

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As the wind speed rises, sand is picked up and carried.

When the wind drops, sand is deposited somewhere else.

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Sand Dunes

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Small heaps of sand gather around small pebbles and rocks.

The heaps grow rapidly and are shaped by the wind.

The tallest sand dunes recorded are over 200 meters high!

Sand Dunes

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Sand dunes are made from billions of grains of sand.

These grains are themselves the result of years of rocks being weathered and eroded.

The picture here is taken from space.

Which landform is it?

Question 3

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A) Glacier

B) Canyon

C) Sand dune

D) Delta

Question 3

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The picture here is taken from space.

Which landform is it?

A) Glacier

B) Canyon

C) Sand dune

D) Delta

A delta is formed when the rocks, sand and soil from weathering and erosion build up on the river bed.

What is this rock, soil and sand called?

Question 4

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A) Deposit

B) Moraine

C) Sediment

D) Rubble

Question 4

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A delta is formed when the rocks, sand and soil from weathering and erosion build up on the river bed.

What is this rock, soil and sand called?

A) Deposit

B) Moraine

C) Sediment

D) Rubble

Which landform resulting from weathering and erosion can be good for farmers?

Question 5

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A) Canyon

B) Sand dune

C) Delta

D) None of the above

Which landform resulting from weathering and erosion can be good for farmers?

Question 5

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A) Canyon

B) Sand dune

C) Delta

D) None of the above

Summary

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how changes to the Earth’s surface are caused by wind, water and ice

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