Activity Overview
Students learn where volcanoes occur by studying the United States Geological Survey map of the global distribution of historically active volcanoes. Students become familiar with the map key and scale. They locate the eruptions that are closest to their community and search for and describe global patterns of eruptions. Students read about the general geologic settings of volcanic eruptions. Students learn that most volcanism occurs beneath the ocean, that there are many volcanoes in the
western states, mainly Washington and Oregon, and that volcanoes are also found in the Caribbean, southern Mexico, and Central America. Content reading explains the relationships between plate tectonics and the distribution of volcanoes that students explore in the activity. This provides a concise summary of the important points made on the USGS map.
Preparation and Materials Needed
The answers to some questions in the activity depend upon where you live. Thus, you should probably complete the activity yourself prior to using it in your class. This will allow you to make “answer keys” for discussing and evaluating student work. You will also become familiar with the challenges that students will face.
Have a copy of the USGS map for each group. Laminate the maps so that they last longer. The USGS map is large and cumbersome. Depending upon the space in your classroom and the number of maps you have available, it might make sense to have larger groups than usual for students to work in for this activity.
Give each student a copy of the Blackline Master of a blank world map on which to draw the distribution of volcanoes. Have extra copies available so students can revise their work for their Chapter Report. Provide colored pencils or crayons to highlight volcanic areas on the world map.
Have meter sticks available. Students can line up two meter sticks on the map
(one for latitude and one for longitude) to pinpoint the coordinates more easily.
Materials
• U.S. Geological Survey Map This Dynamic Planet*
• Metric ruler (30 cm)
• Colored pencil or crayon
• Copy of blank world map (Mercator projection) — see the Blackline Master
Volcanoes 1.1
*Visit the EarthComm web site to find out how to download an Acrobat™ Reader file (PDF) of this map.
Think about It
Student Conceptions
Students who think that the entire interior of the Earth is molten may think that
volcanoes can form anywhere on Earth (so long as there is a conduit for magma to rise through). Some students will know that most volcanoes occur at plate boundaries or the “Ring of Fire.” Students are less likely to know or understand how a volcano can form in the middle of a plate (hot-spot volcanism).
Answer for the Teacher Only
Volcanoes form only in places where mantle material is rising. Since mantle material is not rising everywhere on Earth, volcanoes cannot form anywhere on Earth. Volcanoes form in one of two settings—over a region of upwelling mantle rock (hot spot) and at plate boundaries where lithospheric plates converge or diverge. |