Natural Forces. In this presentation you will: see the changes to the Earth s surface caused by wind, water and ice. Next >

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Steven Williams
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1 Natural Forces In this presentation you will: see the changes to the Earth s surface caused by wind, water and ice

2 Landforms A landform is the name given to the way different parts of the Earth s surface appear, for example: deltas canyons sand dunes

3 Changes to Landforms Landforms sometimes change very quickly. Sometimes they change more slowly.

4 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.

5 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.

6 Weathering Heat from the Sun can cause weathering. The Sun dries the rocks, making some more easily turn to sand.

7 Erosion Erosion most often happens slowly. Erosion is when wind, water and ice carry away small rocks, soil, sand and dust.

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

9 Erosion Wind and flowing water are most often linked to erosion. Glaciers however, are terrifically powerful at causing erosion.

10 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.

11 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

12 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

13 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

14 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

15 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.

16 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.

17 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.

18 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.

19 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.

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

21 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.

22 Sand Dunes As the wind speed rises, sand is picked up and carried. When the wind drops, sand is deposited somewhere else. David_O

23 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!

24 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.

25 Question 3 The picture here is taken from space. Which landform is it? A) Glacier B) Canyon C) Sand dune D) Delta

26 Question 3 The picture here is taken from space. Which landform is it? A) Glacier B) Canyon C) Sand dune D) Delta

27 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

28 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

29 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

30 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

31 Summary In this presentation you have seen: how changes to the Earth s surface are caused by wind, water and ice End >

Earth Science Landforms, Weathering, and Erosion Reading Comprehension. Landforms, Weathering, and Erosion

Earth Science Landforms, Weathering, and Erosion Reading Comprehension. Landforms, Weathering, and Erosion Reading Comprehension Name 1 How many people have been to the Rocky Mountains or the Grand Canyon? When people go to visit these natural wonders, they may not realize that it took millions of years for