tectonic plates

Volcanoes, mid-oceanic ridges, and deep-sea vents are all associated with sea floor spreading and plate tectonics. They are also the newest places on Earth. Volcanoes can affect the ocean and the atmosphere around them.

Locate the Earth's "hot spots"

  1. Have students read about volcanoes in the encyclopedia, trade books, or on the Internet.
  2. Have students record the dates and locations of major volcanic eruptions that they come across in their reading.
  3. On a map in the classroom, have students mark the locations of volcanic eruptions, as well as earthquakes, mentioned in their references. The same places will be mentioned repeatedly, including California, Mexico City, Japan, Alaska, Chile, and Italy. Do the markings of these places make a pattern on the map?
  4. Read about the locations where oceanographers have discovered deep-sea vents and/or the locations of mid-oceanic ridges. Fit these onto the global map. Do they correspond to the plate boundaries?
  5. Satellites can record volcanic eruptions on land and document the changes in ocean and atmospheric temperatures associated with dust particles blocking sun's rays.

Ask students why satellite images can't provide a picture of the extremely high temperatures produced at deep-sea vents and underwater volcanic eruptions. (Because satellites can only record sea surface temperatures.)

  1. Some climatologists have theorized that only low latitudinal eruptions (between 20oN-20oS latitude) can affect the world's climate. Why? Look at a globe to hypothesize an answer.

The Puzzle of Planet Earth

Compare a map of the plate boundaries to the map the students highlighted with earthquake and volcanic activity. They will overlap.

If you looked at a map of the continents bordering the Atlantic Ocean, you would notice that they fit together like the pieces of a giant jigsaw puzzle. This was one of the first clues that persuaded geologists that the continents may once have been joined. The supercontinent that existed 360 million years ago has been named Gondwanaland. It broke into Laurentia and Pangaea.

Students can piece together cut-outs of the continents against the mid-Atlantic Ridge to show how they once may have been joined.

Disaster on the Home Front

Ask students to brainstorm a list of natural disasters. Ask, "Could these events happen in our part of the country?" "Could they have happened here long ago?" "Can they be predicted or prevented?"

Many newspapers carry a summary of the week's environmental disasters, including volcanoes, hurricanes, earthquakes, floods, and blizzards. Students might collect news reports of earthquakes, volcanic eruptions, floods, sea level rise, meteor crashes, and other catastrophic events for their own Earth Diary.

Materials

  • trade books
  • wall map of world
  • markers or pins
  • encyclopedia
  • map of plate boundaries