21.Soils There are many different kinds of soils. Different soils have different types of rock and minerals in them. Some soils have more water in them than others. Some soils might have more plant and animal material in them, too. Different kinds of soils are found in different parts of the world. There are several kinds of soils found in the United States. In some areas, the soil has a lot of clay. Other soils are very sandy. Loam is a kind of soil that has a good mixture of clay and sand. In some places, soil layers are very thick. Lots of plants grow in places with a thick soil layer. In dry and windy places soil layers are much thinner. Layers of soil on mountains are thin because gravity pulls the soil downhill. The type of soil in a particular place affects what kinds of plants can grow there.22. Crisis Life is a contest! Who will win? A bluebird and sparrow both compete for space to build their nests. A fast-growing maple tree and slower-growing dogwood compete for the sunlight they both need. Oil competes with coal and nuclear power as an energy source for electric power plants! There is a problem. There is a limited amount of space for birds, sunlight for trees, and energy for people! If we do not cut back on our uses of some of our resources, someday they will be gone! How can we use energy today and know we will have enough to go around in the future? We can choose alternate, or replacement, energy resources. It takes the earth millions of years to create coal, oil, and gas. They are nonrenewable resources. Solar energy, wind energy and water energy are renewable resources. It takes the earth millions of years to create coal, oil, and gas. They are n...
