United States History Student Edition

Hemispheres Imaginary lines divide Earth into hemispheres.

Western Hemisphere

Eastern Hemisphere

Northern Hemisphere

0° (Equator)

Southern Hemisphere

0° (Prime Meridian)

buildings, streets, and homes. People tunnel through mountains to create roads, and they use nonrenewable resources such as coal to make electricity. People also adapt to the world around them. For example, they use renewable resources, like wind and solar power. Sometimes there are different perspectives on how to use resources since use can have a lasting impact. Florida’s ecosystems have been greatly affected by human development. One clear case is the Everglades, a unique area of lowlands connected by freshwater resources such as rivers, streams, and shallow sheets of water. It has a diverse animal population that includes many varieties of fish, wading birds, and alligators. However, the growth of nearby cities and their need for water has drained many of the original freshwater resources for the Everglades. Today, many of the formerly wet areas are dry, and some freshwater areas near the coasts are now filled with salt water, which is not suitable for drinking. Natural and Environmental Disasters As much as humans can affect the places they live, there are natural occurrences that they often cannot control. Natural disasters are natural events that cause great damage, such as floods, earthquakes, and hurricanes. Environmental disasters are those that are often caused by human action and can often be avoided, such as oil spills and wild fires. Both types of disasters can effect whole ecosystems for a long time.

7 CHECK FOR UNDERSTANDING Determining Central Ideas How do the geographic themes of location and place relate to each other? Using Maps and Globes GUIDING QUESTION How do maps and globes present information? The most accurate way to show Earth is with a globe, a spherical model of the planet. A globe best shows the sizes of continents and the shapes of landmasses and bodies of water. Globes also show true distances and directions. Even so, a globe is not as easy to carry as a map or a map on a device. Maps can show many things—political borders, population densities, or voting results. However, maps cannot show true size, shapes, distance, and direction at the same time. This is because they are flat drawings of a round planet. Hemispheres To locate a place on Earth, geographers use a system of imaginary lines that crisscross the globe. The Equator (ih•KWAY•tuhr) is one of these lines. It circles the middle of Earth like a belt and divides Earth into “half spheres,” or hemispheres (HEH•muh•sfihrz). Everything north of the Equator

hemisphere a “half sphere”; used to refer to one-half of the globe when divided into northern and southern or eastern and western halves

Historian’s Toolkit HT29