Universe Cycle - Earth (3)

  • Comparing water and ice erosion.
  • Discovering how landforms are created on Earth.
  • erosion
  • ice
  • landscape
  • water
  • wind

Students compare and contrast the erosional effects of liquid water and ice.

Ice flowing downhill carves valleys into a mountain range. 


One way in which the Earth differs from all other planets is the presence of abundant water on and within its surface. Water in the three forms of matter (liquid, gas, and solid) make this planet alive, both geologically and biologically.

Liquid water can cause massive changes to the Earth’s surface through weathering and erosion of rock. It transports loose material, wearing down mountains and filling in lakes and valleys. Liquid water also helps plants grow, which may in term enhance erosion and reshaping of the Earth’s surface.

Ice, in the form of glaciers and ice caps, is also a powerful force of erosion and transportation. Ice is restricted to colder areas (high altitudes and high latitudes), but it can cut through just about anything. A glacier can carve its way through a mountain.

Wind is not as strong as water, but over a long period of time it can also erode. In combination with water, wind can be more destructive.

A close up of ice flowing downhill. 
the dirty color is from sediment in the ice

A U-shaped ice cut valley. The ice is
 flowing into the ocean

A V-shaped stream valley in Colorado, USA

This lab compares the two different ways that water erosion works, as a solid (ice) and as a liquid. There are two parts in this activity.

 First, the students compare a landscape created by snow and ice with one formed by running water. This part of the activity uses portions of topographic maps. Topographic maps record precise information about elevations on the Earth’s surface. This appears on the map in the form of brown contour lines. These are imaginary lines of equal elevation. Your students are unlikely to be able to grasp the full concept of contour maps at this point. However, you should explain to them that when contour lines are close together, the landscape is steep (this is typical for glacial landscapes), and when contour lines are far apart, the landscape is flatter. This is more common in landscapes carved by liquid water.

In the second part of this lab students will explore how ice acts as a cutting agent. They will see that ice can cut clay but water cannot. Although this may seem obvious to you, it is often not to students. Landforms created by glaciers tend to be U shaped, while landforms created by rivers tend to be V shaped. The river concentrates its energy just where the river is cutting, whereas a glacier cuts all areas that it covers.


Water flowing downhill in this stream
transports much material

  1. Show the class pictures of the landforms created by ice or running water. The web sites recommended below contain many good examples. Alternatively, if they are available, show the class models of different landscapes. These three dimensional tools are very effective in explaining landscapes to children.
    1. http://geogweb.berkeley.edu/GeoImages.html/  - The Geo_Images Project at UC Berkeley. Contains abundant land and aerial photographs of regions around the world.
    2. Gemorphology from Space, a NASA publication featuring satellite and astronaut photographs. Clearly arranged by process, with good global coverage. 
      The link is:
  2. First, have them examine the maps. They should be able to distinguish the glacial landscape by the presence of white areas of ice and snow. This landscape should look steeper; there are many places where the contour lines are very close together. The other map shows a landscape carved by liquid water, shown by blue lakes and streams. The landscape here should seem flatter to the students.
  3. Have the students set up the lab materials for Exercise 2. They should work in pairs again. Make sure each student gets a chance to experiment with the water and ice. Have them record their observations.

    Niagara Falls. An example of erosion by water


  4. Go over the student’s observations as a group. You can also complete the conclusion as a group. The main point is for the students to realize that ice is an important erosional force in cold climates.

  5. You may want to describe frost wedging to the students. In areas where it gets cold and then warms up during summer you can "mechanically" weather rocks or roads. Water gets into cracks in the road or rock. It freezes in the winter which expands the crack (remember that water expands when it freezes). When the warm weather comes and the ice melts, the crack is larger. As this process repeats, the road or rock is gradually broken into pieces. Remind students that when a can of soda freezes it can burst the can! 

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