The Processes that Shape Landforms

Robyn Auld & Let's Talk Science
Readability
7.8

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Canada has some amazing landforms. Learn how weathering, erosion and deposition shape landforms.

When it comes to landforms, Canada pretty much has it all. There are mountains and valleys, rolling hills and plains, and even some fjords!

A landform is any surface feature on Earth. Landforms create the planet’s different natural landscapes. They provide homes for wildlife and humans. A place’s landforms make up its topography. In other words, topography is how landforms are laid out in a particular area.

Landforms can create stunning views. The topography of a place like the Grand Canyon can be downright spectacular. But what's really interesting is how these landforms develop and disappear!

Did you know?

Topography is the study of land surfaces. This includes geography and differences in elevation. These changes in height are called relief.

Weathering is one major process that shapes different landforms. Temperature and precipitation both contribute to weathering. So does pressure on rocks, minerals and soil. These are examples of mechanical weathering. Chemical reactions can also cause rocks, minerals and soil to break down. 

What is mechanical weathering?

Mechanical weathering breaks the Earth’s materials apart. 

One example is frost weathering, which is sometimes called cryofracturing. It happens when water gets into tiny cracks in rocks. The water expands when it freezes, causing the rock to break apart. As the freeze-thaw cycle continues, more water can get into the cracks and break the rock apart even more.

Rock split by frost weathering
Rock split by frost weathering (Source: Till Niermann [CC BY-SA 3.0] via Wikimedia Commons).

 

Pressure from inside the Earth can also cause mechanical weathering. Liquid rock called magma is trapped under the planet’s surface, along with different gases. These materials are very hot and under a lot of pressure. When magma and gases rise toward the surface, they sometimes create cracks that release the pressure. That’s what happens when a volcano erupts! 

Did you know?

Magma is molten rock found under the Earth’s surface. When magma reaches the surface, it’s called lava.

What is chemical weathering?

Chemical weathering changes in the chemical properties of materials on Earth’s surface. 

One example is carbonation. It happens when acid rain falls on rocks that contain calcium carbonate (CaCO3). For instance, limestone often breaks down because of carbonation. The sulfuric acid in acid precipitation reacts with the limestone. This replaces the rock with a new chemical product, called calcium bicarbonate Ca(HCO3)2.

Oxidation also causes chemical weathering. Oxygen in the air reacts with chemicals in different landforms. Colour change is a common sign of oxidation, especially in rock formations that contain a lot of iron. When iron is exposed to oxygen, a redox reaction produces iron oxide. That’s a fancy word for rust! 

 

A freshly broken piece of sandstone shows an outer layer of reddish oxidized rock
A freshly broken piece of sandstone shows an outer layer of reddish oxidized rock (Source: Pollinator via Wikimedia Commons).

 

Did you know?

Copper also changes colour as it oxidizes. The copper roof towers of the Parliament Buildings in Ottawa are known for being green. Thanks to some new copper, they now look more like pennies!  

What other geological processes affect landforms?

Erosion is another geological process that creates landforms. 

When mechanical and chemical weathering breaks up materials on the Earth’s surface, erosion can move them to new locations. For example, wind, water or ice can create a valley by removing material. Plateaus can also be formed this way. 

Of course, the material that gets carried away doesn’t just disappear. When layers of eroded material pile up, it’s called deposition. This can create new landforms. For example, coastal deposition is how beaches are formed. When eroded material is deposited at the mouth of the river, a river delta is formed.

Mackenzie River Delta in the Northwest Territories
Mackenzie River Delta in the Northwest Territories. This image was taken by the National Aeronautics and Space Administration (NASA) Terra satellite on August 4, 2005 (Source: NASA).

The constant downward pull of gravity can also change the landscape by creating new landforms. Gravitational erosion can involve small bits of soil slowly tumbling down a hill over many years. Or it can involve giant slabs of soil or rock suddenly giving way in a landslide. 

There are many other forces that shape landforms on Earth. People have built entire careers on studying how these features form and change. Geologists, geographers and other Earth scientists are constantly finding out more about our planet's fascinating topography!

Starting Points

Connecting and Relating

  • What are some examples of weathering, erosion and deposition in your community? 
  • Choose a natural topological feature in your area and identify the processes you think created these features.
  • Do the roads in your community develop potholes? Describe the steps of weathering and erosion that lead to the formation of these potholes.
  •  

Connecting and Relating

  • What are some examples of weathering, erosion and deposition in your community? 
  • Choose a natural topological feature in your area and identify the processes you think created these features.
  • Do the roads in your community develop potholes? Describe the steps of weathering and erosion that lead to the formation of these potholes.
  •  

Relating Science and Technology to Society and the Environment

  • Some of the tallest mountains in the world exist underwater at the mid-Atlantic ridge. Explain why these mountains have jagged peaks while mountains in northern Canada have rounded tops.
  • Has the construction of cities changed the way that weathering and erosion naturally works? Explain.
  • Potholes in pavement are created by the same processes that create landforms on Earth. Do you think we will ever have a pavement that can withstand these processes? Explain.
  •  

Relating Science and Technology to Society and the Environment

  • Some of the tallest mountains in the world exist underwater at the mid-Atlantic ridge. Explain why these mountains have jagged peaks while mountains in northern Canada have rounded tops.
  • Has the construction of cities changed the way that weathering and erosion naturally works? Explain.
  • Potholes in pavement are created by the same processes that create landforms on Earth. Do you think we will ever have a pavement that can withstand these processes? Explain.
  •  

Exploring Concepts

  • What is the difference between weathering and erosion?
  • What is the difference between mechanical and chemical weathering?
  • Weathering, erosion and deposition are processes that can wear a mountain down. If Earth is billions of years old, why isn’t it all flat?
  •  

Exploring Concepts

  • What is the difference between weathering and erosion?
  • What is the difference between mechanical and chemical weathering?
  • Weathering, erosion and deposition are processes that can wear a mountain down. If Earth is billions of years old, why isn’t it all flat?
  •  

Nature of Science/Nature of Technology

  • Older tombstones in Canada were generally made from limestone. More recently granite has been used instead of limestone. What role do you think our understanding of the science behind erosion played in this change? Explain.
  • Landslides that result from a rapid downward movement of a mass of rock and earth can cause major damage to structures created by humans as well as cause loss of life. While scientists have developed a good understanding of how and why these events occur, they are not able to accurately predict when an event will occur. Should scientists have the power to specify where houses can be built based on their understanding of the potential for a landslide to occur? Why or why not?

Nature of Science/Nature of Technology

  • Older tombstones in Canada were generally made from limestone. More recently granite has been used instead of limestone. What role do you think our understanding of the science behind erosion played in this change? Explain.
  • Landslides that result from a rapid downward movement of a mass of rock and earth can cause major damage to structures created by humans as well as cause loss of life. While scientists have developed a good understanding of how and why these events occur, they are not able to accurately predict when an event will occur. Should scientists have the power to specify where houses can be built based on their understanding of the potential for a landslide to occur? Why or why not?

Media Literacy

  • The 2009-2010 television series Life After People used scientific specialists to extrapolate how Earth would appear in the absence of humans. Explore images of this series on the Internet and identify those that demonstrate the impact of the landform-shaping processes that are described in this article.
  • Images in tourism advertisements often use examples of topographical features. What is the purpose of highlighting landform features in advertisements that seek to get people to visit a location? Explain.
  •  

Media Literacy

  • The 2009-2010 television series Life After People used scientific specialists to extrapolate how Earth would appear in the absence of humans. Explore images of this series on the Internet and identify those that demonstrate the impact of the landform-shaping processes that are described in this article.
  • Images in tourism advertisements often use examples of topographical features. What is the purpose of highlighting landform features in advertisements that seek to get people to visit a location? Explain.
  •  

Teaching Suggestions

  • This article can be used to support teaching and learning of Earth Science, Rocks and Earth materials and processes related to weathering, erosion and deposition. Concepts introduced include landform, topography, weathering, mechanical weathering, frost weathering, disintegrate, expands, magma, tectonic plates, chemical weathering, carbonation, acid rain, oxidation, redox reaction, erosion, valleys, plateaus, gravitational erosion and gravity. 

  • Before reading this article, teachers could have students complete a Vocabulary Preview learning strategy to engage prior learning and introduce new terminology. Ready-to-use Vocabulary Preview reproducibles for this article are available in [Google doc] and [PDF] formats.

  • After reading this article, teachers could have students complete a Concept Definition learning strategy for the concept of erosion. Download ready-to-use reproducibles using the Concept Definition Web learning strategy for this article in [Google doc] and [PDF]. 

  • Alternately, to help consolidate learning, teachers could have students create a graphic organizer that defines and organizes the different types of weathering and erosion that have been discussed in the article. 

Teaching Suggestions

  • This article can be used to support teaching and learning of Earth Science, Rocks and Earth materials and processes related to weathering, erosion and deposition. Concepts introduced include landform, topography, weathering, mechanical weathering, frost weathering, disintegrate, expands, magma, tectonic plates, chemical weathering, carbonation, acid rain, oxidation, redox reaction, erosion, valleys, plateaus, gravitational erosion and gravity. 

  • Before reading this article, teachers could have students complete a Vocabulary Preview learning strategy to engage prior learning and introduce new terminology. Ready-to-use Vocabulary Preview reproducibles for this article are available in [Google doc] and [PDF] formats.

  • After reading this article, teachers could have students complete a Concept Definition learning strategy for the concept of erosion. Download ready-to-use reproducibles using the Concept Definition Web learning strategy for this article in [Google doc] and [PDF]. 

  • Alternately, to help consolidate learning, teachers could have students create a graphic organizer that defines and organizes the different types of weathering and erosion that have been discussed in the article. 

Learn more

The Cracks Ripping Earth Apart (2016)

Article from BBC Earth discussing the cracks that have formed in the surface of the Earth in Iceland due to volcanic activity and trapper thermal energy. Note that this resource was also used as a reference.

Landform Regions of Canada

Interactive map by David Dexter including information about the different landforms in Canada.

Joffre Peak – A Known Producer 

Personal blog that includes high-resolution videos and photos of Joffre Peak, Pemberton BC landslide that occurred in May, 2019.

References

Cook, M. (2018, March 23). How does gravity cause erosion? Sciencing.

Helmenstine, A. M. (2019, July 9). 4 types and examples of chemical weathering. ThoughtCo.

National Geographic. (2018, April 19). Weathering.

Shaw, E. (2018, March 13). What is the difference between erosion and deposition? Sciencing.

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