Natural Forces
In this presentation you will: see the changes to the Earth’s surface caused by
wind, water and ice Next > Landforms
A landform is the name given to the way different parts of the Earth’s surface appear, for example:
deltas
canyons
sand dunes
Next > Changes to Landforms
Landforms sometimes change very quickly. Sometimes they change more slowly.
Next > Changes to Landforms
Weathering and erosion are Volcanoes and much slower ways that give earthquakes can us our landscape. alter the shape of the Earth’s surface in a few moments. Next > Weathering
Weathering is usually a slow change. It breaks rocks apart and changes landscape.
If water gets into a crack in a rock and then freezes, it expands. It can then cause larger cracks.
After years of freezing and thawing, rocks break apart. Next > Weathering
Heat from the Sun can cause weathering.
The Sun dries the rocks, making some more easily turn to sand.
Next > Erosion
Erosion most often happens slowly.
Erosion is when wind, water and ice carry away small rocks, soil, sand and dust.
Next > Erosion
Large amounts of falling rocks, mud or snow can erode the Earth’s surface much more quickly. Next > Erosion
Wind and flowing water are most often linked to erosion.
Glaciers however, are terrifically powerful at causing erosion. Next > Erosion
The frozen water in a glacier moves extremely slowly, but can carve a vast valley. Glaciers deposit huge amounts of rock, called moraine, where they melt. Next > Question 1
What happens naturally to water to make cracks in rocks and break them up? A) It boils
B) It evaporates
C) It freezes
D) It melts
Next > Question 1
What happens naturally to water to make cracks in rocks and break them up? A) It boils
B) It evaporates
C) It freezes
D) It melts
Next > Question 2
What is the name used to describe wind, water and ice carrying away small rocks, soil, and sand? A) Weathering
B) Erosion
C) Evaporation
D) Climate change
Next > Question 2
What is the name used to describe wind, water and ice carrying away small rocks, soil, and sand? A) Weathering
B) Erosion
C) Evaporation
D) Climate change
Next > Canyons
Canyons are formed by the water moving in a river.
The water carries away bits of weathered rock and sand, and the river bed sinks lower.
Next > Canyons
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.
Next > Deltas
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. Next > Deltas
When the river nears the sea, it slows.
The rocks, soil and sand that the river is carrying, is called sediment. This drops to the river bed.
The level of the river bed rises. The flow slows further, and even more sediment is deposited. Next > Deltas
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.
Next > Deltas
Deltas make excellent farmland because sediment is rich in minerals and fresh water is always nearby.
Next > Sand Dunes
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. Next > Sand Dunes
As the wind speed rises, sand is picked up and carried.
David_O When the wind drops, sand is deposited somewhere else.
Next > Sand Dunes
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!
Next > Sand Dunes
Sand dunes are made from billions of grains of sand.
These grains are themselves the result of years of rocks being weathered and eroded. Next > Question 3
The picture here is taken from space. Which landform is it?
A) Glacier
B) Canyon
C) Sand dune
D) Delta
Next > Question 3
The picture here is taken from space. Which landform is it?
A) Glacier
B) Canyon
C) Sand dune
D) Delta
Next > Question 4
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
Next > Question 4
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
Next > Question 5
Which landform resulting from weathering and erosion can be good for farmers? A) Canyon
B) Sand dune
C) Delta
D) None of the above
Next > Question 5
Which landform resulting from weathering and erosion can be good for farmers? A) Canyon
B) Sand dune
C) Delta
D) None of the above
Next > Summary
In this presentation you have seen:
how changes to the Earth’s surface are caused by wind, water and ice
End >