A volcano is an opening in the Earth's surface through which red-hot lava (melted rock) and gases spew into the air.
Most volcanoes are located where the large, rigid plates that make up the Earth's surface continually move toward or away from each other, colliding or spreading apart,
The Earth has about 1,500 volcanoes. which are located both on land and at the bottom of the sea. Many others are dormant (not active), or extinct.
On land, some eruptions have been so violent that they have wiped out entire towns and killed thousands of people. In 79 A.D., a volcanic eruption destroyed the Roman city of Pompeii (pahm-PAY). The word volcano comes from Vulcan, the Roman god of fire.
Volcanoes are found on every continent. But the largest number are located along a belt known as the Ring of Fire, which nearly circles the Pacific Ocean (see map). The map shows the location of major volcanoes. It is not possible to show the location of every volcano. Iceland, for example, has more than 30 active volcanoes, one of which erupted spectacularly on November 4. Study the map, and then answer the questions.
How do volcanoes form? Earth's surface has three layers: a thin crust, a layer beneath the crust called the mantle, and a core in the center. Volcanoes erupt when melted rock, or magma, gushes up from the mantle and breaks through a weak spot in the crust (Magma that has erupted is called lava.)
Earth's crust looks like a giant jigsaw puzzle. The puzzle pieces--or plates--move slowly; But they continually collide with each other or pull apart.
Scientists call the places where the plates bang together subduction zones.
Students should understand
* a volcano is an opening in Earth's surface through which gases and melted rock spew into the air.
* WORDS TO KNOW
lava: molten rock that flows from a volcano
* Ring of Fire: a zone of frequent volcanic eruptions that nearly encircles the Pacific Ocean.
* TEACHING STRATEGY
Ask students: "What would you do if you lived near a volcano and it started to rumble?"
One of the most destructive eruptions in modern history occurred at Krakatau, a volcano in Indonesia, on August 26, 1883. A series of eruptions--one of which could be heard in Australia--generated huge, destructive ocean waves known as tsunamis. The giant waves, fumes, and ash killed about 36,000 people on nearby islands. Scientists believe the dust released by Krakatau might have been the cause for a worldwide drop in temperature that lasted for years.
* CRITICAL THINKING
NOTING DETAILS: In which region of the continental United States are most volcanoes located? (the Pacific Northwest)
COMPREHENSION: Where are volcanoes located in general? (Volcanoes can be found both on land and at the bottom of the sea. Most volcanoes are located in areas where the large plates that make up Earth's surface continually collide with each other or pull apart.)
VOLCANIC NEIGHBORS: Instruct students to research the agricultural advantages of settling in an area of a volcano. Students can create a poster or present an oral report describing how eruptions have benefited the agricultural life of a region.
SOCIAL STUDIES, GRADES 5-8
* People, places, and environment: How volcanoes form on Earth's surface and how volcanic eruptions affect the physical environment and the lives of the people nearby.
1. What does magma turn into after it erupts?--
2. The Ring of Fire nearly circles which ocean?--
3. Which U.S. state at 21[degrees]N, 157[degrees]W has several volcanoes?--
4. Name the volcanic islands located on the equator, west of Ecuador.--
5. Which Northern European island country has a large number of volcanoes?--
6. Which mountain chain in South America is located on the Ring of Fire?--
7. Which chain of volcanic islands extends west from the state of Alaska?--
8. Mount St. Helens is located 95 miles from which city?--
9. Mount St. Helens is located in which direction from Olympia, Washington?--
10. What do scientists call the places where Earth's plates bang together?--
2. Pacific Ocean
4. Galapagos Islands
6. Andes Mountains
7. Aleutian Islands
8. Seattle, Washington
10. subduction zones
* Use a word from the list to correctly complete each sentence.
79, 1,500, Andes Mountains, Arctic, Atlantic, Iceland, lava, magma, Pacific, Pompeii, three, Vulcan, Washington
21. Mount St. Helens is located in--
22. The melted rock that has erupted from a volcano is--.
23. Earth's--volcanoes are located on land and under the sea.
24. The Ring of Fire is a belt of volcanoes that nearly circles the--Ocean.
25. --has more than 30 active volcanoes, one of which erupted on November 4, 2004.
* Kunhardt, Edith, Pompeii ... Buried Alive! (Random House, 2003). Grades 5-8.
* Van Rose, Susanna, Volcano (DK Publishing, 2004). Grades 5-8.
GROLIER WEB SITE KEY TERM
* Weekly Volcanic Activity Report www.volcano.si.edu/reports/usgs
* Mount St. Helens Web Cam www.fs.fed.us/gpnf/volcanocams/msh
|Printer friendly Cite/link Email Feedback|
|Date:||Nov 29, 2004|
|Previous Article:||Thomas Jefferson and the Declaration of Independence for Thomas Jefferson, the pen truly was mightier than the sword.|
|Next Article:||Political cartoon.|