Universe Cycle - Earth (5)
 Lab 

   
OBJECTIVES:
  • Comparing the Earth’s eastern and western hemispheres.
  • Discovering the influence of ice, rain, and wind.
VOCABULARY:
  • erosion
  • ice
  • rain
  • wind
MATERIALS:

Students plot areas of erosion on a map of the world.

BACKGROUND:

The Earth's landscape is influenced by many forces, including water, ice, and wind. Plate Tectonics or the movement of the Earth's crust is also very important as it creates volcanoes, mountains, and valleys. Students should understand that one of the ways that the Earth differs from the other planets is the effects of these three forces on its surface. Liquid water is the most important agent of weathering, erosion, and transport on the Earth’s surface. As water runs downhill, it carves valleys, transports loose material, and fills in low areas. Most of the Earth’s surface is in fact covered by stream valleys. Landslides, which are downhill movements of large masses of loose rock and soil, are also common in areas of running water. Water adds lubrication to loose material, making landslides easier to move.

Solid water, or ice, is an effective agent where it is cold, including mountainous areas (high altitudes) and near the poles (high latitudes). As they move downhill, glaciers and icecaps act like giant sheets of sandpaper or like files. They can carve away both loose material and solid rock. Mountain glaciers carve deep valleys. Ice sheets, like the ones covering Antarctica and Greenland, flatten landscapes by grinding away all the high areas.

Wind is only powerful enough to erode and transport dust- and sand-sized material. Larger particles only move during catastrophic storms. Although winds blow over much of the Earth’s surface, the effects of the wind are best visible in arid, or desert regions. Here the effects of water are subdued, and the wind can pile up sand dunes and blow dust for long distances. For this reason, deserts and wind activity are often equated. This is a reasonable approximation for students. Be aware however, that winds are also strong enough in other areas, such as along coastlines to form sand dunes and other "windy" landscapes.

The globes also show lines of longitude and latitude. These are a system for locating a point on the Earth’s surface. Longitude lines run from pole to pole. They increase in value eastward from the 0o line, which run through England. Note that the 180o line, halfway around the globe, is also the international date line. Latitude lines run from east to west. The equator is the line of 0o latitude. Lines of latitude increase in value toward the North and South Poles, which are at 90o N and 90oS, respectively. Every point on the Earth’s surface has a unique latitude and longitude location.

In North America ice dominates the northern portion of Canada, portions of Alaska, and Greenland. Water is the main influence wherever there are rivers. Desert-like areas are present in the American southwest and portions of Mexico. Central America, and most of northern South America are dominated by water. There are many deserts in South America, especially in portions of Chile and Argentina. In the southern tip of South America, ice influences the landscape.

Africa is a continent that most people associate with jungles. However, as the students look at the Inflatable World Globe, they will notice that northern Africa is dominated by desert. A wide band of river-dominated area occurs in central Africa; some of this is true jungle. The southern part of Africa is a mixture of river and desert areas.

The European portion of the Eurasian continent is dominated by rivers, so again water is the major factor. In some areas of the northern Eurasian continent, ice dominates. In the central portion of the Eurasian continent, desert is very common.

Australia is dominated by a desert-like climate, so wind is important. Antarctica on the other hand is dominated by ice.

In terms of patterns, students should be able to see that areas at high latitudes are dominated by ice. In addition, they may also notice that desert areas occur in two bands, located 30o-40o north and south of the equator.

PROCEDURE:
  1. Introduce students to the forces of wind, water, and ice. Explain that they will be examining the inflatable globes to try and learn the distribution of these forces on the Earth’s surface.  Discuss how Plate Tectonics can move the surface of the Earth, either by volcanoes or faulting.
     
  2. Point out the longitude and latitude lines on the globes. Explain their meaning to the class. You may wish to find the latitude and longitude of your location, and have the students try and find it on their globes.

  3. The following provides information on each of the models in the Landform Model kit.


  4. Volcano Model:  formed mainly by plate tectonics
    Mountains with Glaciers Model:  these valleys are formed mainly by ice carving the valleys
    Uplifted Mountains: Faults caused one side to be uplifted, but the incised valleys are caused by water eroding the mountains after plate tectonics. 
    Folded Mountains: Plate tectonics (converging plates) caused folding, but water or wind could have eroded the mountains and valleys smooth.

    In Exercise 3, the students take information from the globe and transfer it to the worksheet. Have them color the continents appropriately. Make plenty of allowance for interpretation in their answers.
     

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