Protecting Earth's Surface

Book excerpt: Earth's surface is constantly being changed by heat, water, ice, salt, plants, and animals. Sometimes the changes are destructive to human activities such as farming and the building of structures. This interesting title shows the different ways people try to stop or reduce this change in the land. Examples feature such structures as dikes to hold back water and windbreaks, and adding shrubs, grass, and trees to an area of land to prevent erosion. Teacher's guide available.