Volcanoes Ppt Grade 9 Free Download
Sebrina Trottier
Volcanoes can be destructive. But they can also create new land. The Hawaiian Islands were created by the eruptions of shield volcanoes. These large, low-lying volcanoes are made up almost entirely of layers of hardened lava.
Steam and poisonous gases also escape from volcanoes. Sometimes these gases are mixed with ash and other hot debris. This mixture travels outward in destructive fiery clouds, called pyroclastic flows.
Some of the most violent eruptions take place where the edge of one plate is forced beneath the edge of another. This forces magma to rise to the surface. Hot gases in the magma make these volcanoes very explosive. Most volcanoes of this type are found around the edges of the Pacific Ocean. This huge circle of volcanoes is known as the Ring of Fire.
Stratovolcanoes, also called composite volcanoes, are mountains shaped like cones. They have a narrow top with steep sides and a wide bottom. A crater, or bowl-shaped pit, usually lies at the top. Stratovolcanoes are made up of layers of hardened lava and ash. Thousands of eruptions left these layers over millions of years. Mount Fuji in Japan is a stratovolcano.
Shield volcanoes are dome-shaped mountains built by lava flows. They are not as steep as stratovolcanoes, though they can be quite large. Some shield volcanoes that erupt under the sea grow high enough to create islands. The volcanoes of Hawaii are shield volcanoes.
Volcanology is the branch of geology that focuses on volcanoes. Many volcanologists work in observatories, from which they keep track of earth tremors and other signs of volcanic activity. Others venture forth to the slopes and craters for an even closer look. On the basis of what they measure and see, they try to predict when an eruption might take place, how severe it will be, and which places will be in the danger zone. Their job is important because it is difficult or impossible to get out of the path of a big eruption once it begins.
The heat within Earth that is released in volcanoes is an enormous potential source of energy. This energy, called geothermal energy, is difficult for people to control. However, hot water and steam trapped below the surface have been used to heat homes and greenhouses and to produce electric power in several countries, including Italy, New Zealand, Japan, Iceland, and the United States.
The word volcano comes from the name of Vulcan, the ancient Roman god of fire and metalworking. The Romans believed that volcanic eruptions resulted when Vulcan made thunderbolts and weapons for the gods. Other cultures explained volcanoes as outbursts of anger from a god or goddess. Pele was the name of the volcano goddess of the native Hawaiians.
The 1980 eruption of Mount Saint Helens, in the U.S. state of Washington, was one of the biggest in North America. The 1991 eruption of Mount Pinatubo, in the Philippines, was the largest of the 1900s. These eruptions killed fewer people than earlier volcanoes, but they still destroyed much property.
Every year about 60 volcanoes erupt, but most of the activity is pretty weak. How do volcanologists measure how big an eruption is? There is not any single feature that determines the "bigness", but the following eruption magnitude scale - called the Volcanic Explosivity Index or VEI - is based on a number of things that can be observed during an eruption. According to this scale, really huge eruptions don't happen very often, luckily!
Since 7th grade focuses on Earth and Space science, the class had a large unit on tectonic activity and volcanoes. They were required to decide on a type of model to create, and they had the freedom to design the type of reaction used to make the volcano explode.
Deep inside Earth, between the molten iron core and the thin crust at the surface, there is a solid body of rock called the mantle. When rock from the mantle melts, moves to the surface through the crust, and releases pent-up gases, volcanoes erupt.
These steep-sided volcanoes erupt in an explosive manner. In fact, Mount Vesuvius is a composite volcano that is most famous for burying the ancient Roman city of Pompeii in up to 20 feet of volcanic ash in 79 AD. The explosiveness of their eruptions is due to the thick, highly viscous lava that is produced by composite cone volcanoes.
Volcanoes are located all over the world. They are most often found at Tectonic Plate boundaries which are designated by the light blue lines on the above map. The active volcanoes are found as red triangles on the above map.
Students express what they learned about volcanoes while practicing essential literacy skills with one or more of the following activities. Differentiate by assigning ones that meet individual student needs.
Discover how rocks are formed from volcanoes during a geology pre-lab activity. Third graders describe the volcanic rock samples and creating a model of Mt. Lassen, located in California. The lesson culminates in a discussion about how volcanoes can form different types of rocks.
Elders and colleagues report in the March issue of the journal GEOLOGY, published by the Geological Society of America, that although the Krafla volcano, like other volcanoes in Iceland, is basaltic (a volcanic rock containing 45-50 percent silica), the magma they encountered is a rhyolite (a volcanic rock containing 65-70 percent silica).
Composite volcanoes are steep-sided volcanoes composed of many layers of volcanic rocks, usually made from high-viscosity lava, ash and rock debris. These types of volcanoes are tall conical mountains composed of lava flows and other ejecta in alternate layers, the strata that give rise to the name.
Shield volcanoes are volcanoes shaped like a bowl or shield in the middle with long gentle slopes made by basaltic lava flows. These are formed by the eruption of low-viscosity lava that can flow a great distance from a vent.
They generally do not explode catastrophically. Since low-viscosity magma is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland, as well.
The unit covers approximately two weeks of instruction and strives to integrate volcanoes into the five subject areas of art, language arts, mathematics, science, and social studies. Students are initially introduced to volcanoes as geographic elements that shape out land and continually change our planet. Focus questions include: What are the types of volcanoes? What are the parts of volcanoes? What are the effects of volcanic eruptions? What effects do volcanoes have on the environment? How do volcanoes work?
Possible English Language Arts integration questions include: How may science fiction present volcanoes? What role does persuasive speech play in communicating safety issues surrounding volcanic eruptions? Why are people concerned about volcanic eruptions? How can you obtain information concerning professions in the study of volcanoes? How are people informed of volcanic eruptions? How can volcano information be shared with the general public?( News Article lesson)
Assessment: Assess understanding during conference time and during the share. Ask follow up questions if students are not confident with their explanations. Assessment of student work based on Rubric. Have students write paragraphs explaining the reasons why earthquakes and volcanoes tend to occur on plate boundaries.
Exploration: Review with your students what they have learned about volcanoes. In discussing what they know about volcanoes, bring out the following background information:
The state of Hawaii wants to invest money in protecting residents and communities from volcanoes. Which solution would be the most beneficial to residents and reduce the impact of a volcanic eruption?
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