Q. So,I have this test coming up and I want to get 100%. So help please. It is in the 6th grade science book. Chapter 7 Volcanoes.
Answer
There isn't enough room here to tell you everything about volcanoes, but I'll give you a general rundown.
"A volcano is a hole in Earth's surface through which magma (called lava when it reaches Earth's surface), hot gases, ash, and rock fragments escape from deep inside the planet. The word volcano also is used to describe the cone of erupted material (lava and ash) that builds up around the opening.
Volcanic activity is the main process by which material from Earth's interior reaches its surface. Volcanoes played a large part in the formation of Earth's atmosphere, oceans, and continents. When Earth was new, the superheated gases within it (including carbon dioxide) streamed out through countless volcanoes to form the original atmosphere and oceans.
Volcanoes are found both on land and under the oceans (where they are called seamounts). Geologists label volcanoes by their periods of activity. If a volcano is erupting, it is called active. If a volcano is not presently erupting but might at some future date, it is called dormant. If a volcano has stopped erupting forever, it is called extinct. Generally, volcanoes are labeled extinct when no eruption has been noted in recorded history.
Most volcanoes form on land near coastal areas when a continental (land) plate and an oceanic plate converge or move toward each other. Since the oceanic plate is denser, it subducts or sinks beneath the continental plate. As the rock of this subducted oceanic plate is pushed farther and farther beneath the continent's surface, extremely high temperatures and pressure melt the rock. This creates hot, buoyant magma that then rises toward the surface. When the magma reaches the crust, it collects in a magma reservoir or chamber. When pressure inside the reservoir exceeds that of the overlying rock, magma is forced upward through cracks in Earth's crust." The largest number of these are part of the "Ring of Fire" around the edge of the Pacific Ocean.
Some volcanoes are formed away from plate boundaries, as the plate moves across a hot spot in the mantle. The Hawaiian Islands are an example of this. The chain of volcanic islands has formed as the Pacific Plate moves over the hot spot. The big Island, Hawaii, still has 2 active volcanoes, Mauna Loa and Kilauea, but it is slowly moving away from the hot spot. A new seamount volcano, Loihi, has formed to the southeast of Hawaii.
Volcanoes also occur at divergent plate boundaries. The volcanoes in Iceland are examples of this.
The size and shape of a volcano is dependent on the history and type of its eruptions. Based on this, geologists classify volcanoes into four shapes: cinder cones, composite cones, shield volcanoes, and lava domes.
Cinder cones are built of lava fragments. They have slopes of 30 to 40 degrees and seldom exceed 1,640 feet (500 meters) in height. Sunset Crater in Arizona and ParÃcutin in Mexico are examples of cinder cones.
Composite cones (or stratovolcanoes) are made up of alternating layers of lava, ash, and solid rock. They are characterized by slopes of up to 30 degrees at the summit, tapering off to 5 degrees at the base. Mount Fuji in Japan and Mount St. Helens in Washington are composite cone volcanoes.
Shield volcanoes are built primarily by a series of lava flows that pile one on top of another. Their slopes are seldom more than 10 degrees at the summit and 2 degrees at the base. The Hawaiian Islands are clusters of shield volcanoes. Mauna Loa (on the island of Hawaii) is the world's largest active volcano, rising 13,680 feet (4,170 meters) above sea level. Kenya's Mount Kilamanjaro, the tallest mountain in Africa, is a shield volcano.
Lava domes are made of thick, pasty lava squeezed like toothpaste from a tube. Examples of lava domes are Lassen Peak and Mono Dome in California.
Volcanoes erupt different material, and they each have their own style of erupting. These varied eruptions result from the differences in magma that each volcano contains. Magma that is low in gas and silica (silicon dioxide, a compound found widely in rocks and minerals) yields a gentle flow of thin, quickly spreading lava. In contrast, magma that is rich in gas and silica gives rise to violent explosions: the thick, tarlike magma may plug up the volcanic vent, blocking the upward movement of the magma until built-up pressure blows away the overlying rock. Geologists classify volcanic eruptions according to four chief forms or phases: Hawaiian, Strombolian, Vulcanian, and Peleean.
In a Hawaiian phase, runny lava gushes out in a fountain without any explosive eruptions. In a Strombolian phase (named after the Stomboli volcano on an island north of Sicily), thick lava is emitted in continuous but mild explosions. Lava arcs and steam-driven clouds of ash shower the dome with molten drizzle. A Vulcanian phase occurs when a magma plug has blocked the volcanic vent. The resulting explosive eruption hurls tons of almost solid magma into the sky, and a vapor cloud forms over the crater. The most violent eruption is the Peleean, named after Mount Pelee on the Caribbean island of Martinique. Fine ash, thick lava, and glowing, gas-charged clouds are emitted, traveling downhill at a tremendous speed. This is called a pyroclastic cloud or pyroclastic flow.
When a volcano erupts such a large volume of material, often emptying its magma chamber, the central part of the cone is left unsupported. As a result, the crater and walls of the vent collapse into the hollow chamber, creating a large circular depression known as a caldera across the summit. The famous Crater Lake in southern Oregon formed in this way.
There is lots more information at the referenced site.
http://www.scienceclarified.com/Vi-Z/Volâ¦
There isn't enough room here to tell you everything about volcanoes, but I'll give you a general rundown.
"A volcano is a hole in Earth's surface through which magma (called lava when it reaches Earth's surface), hot gases, ash, and rock fragments escape from deep inside the planet. The word volcano also is used to describe the cone of erupted material (lava and ash) that builds up around the opening.
Volcanic activity is the main process by which material from Earth's interior reaches its surface. Volcanoes played a large part in the formation of Earth's atmosphere, oceans, and continents. When Earth was new, the superheated gases within it (including carbon dioxide) streamed out through countless volcanoes to form the original atmosphere and oceans.
Volcanoes are found both on land and under the oceans (where they are called seamounts). Geologists label volcanoes by their periods of activity. If a volcano is erupting, it is called active. If a volcano is not presently erupting but might at some future date, it is called dormant. If a volcano has stopped erupting forever, it is called extinct. Generally, volcanoes are labeled extinct when no eruption has been noted in recorded history.
Most volcanoes form on land near coastal areas when a continental (land) plate and an oceanic plate converge or move toward each other. Since the oceanic plate is denser, it subducts or sinks beneath the continental plate. As the rock of this subducted oceanic plate is pushed farther and farther beneath the continent's surface, extremely high temperatures and pressure melt the rock. This creates hot, buoyant magma that then rises toward the surface. When the magma reaches the crust, it collects in a magma reservoir or chamber. When pressure inside the reservoir exceeds that of the overlying rock, magma is forced upward through cracks in Earth's crust." The largest number of these are part of the "Ring of Fire" around the edge of the Pacific Ocean.
Some volcanoes are formed away from plate boundaries, as the plate moves across a hot spot in the mantle. The Hawaiian Islands are an example of this. The chain of volcanic islands has formed as the Pacific Plate moves over the hot spot. The big Island, Hawaii, still has 2 active volcanoes, Mauna Loa and Kilauea, but it is slowly moving away from the hot spot. A new seamount volcano, Loihi, has formed to the southeast of Hawaii.
Volcanoes also occur at divergent plate boundaries. The volcanoes in Iceland are examples of this.
The size and shape of a volcano is dependent on the history and type of its eruptions. Based on this, geologists classify volcanoes into four shapes: cinder cones, composite cones, shield volcanoes, and lava domes.
Cinder cones are built of lava fragments. They have slopes of 30 to 40 degrees and seldom exceed 1,640 feet (500 meters) in height. Sunset Crater in Arizona and ParÃcutin in Mexico are examples of cinder cones.
Composite cones (or stratovolcanoes) are made up of alternating layers of lava, ash, and solid rock. They are characterized by slopes of up to 30 degrees at the summit, tapering off to 5 degrees at the base. Mount Fuji in Japan and Mount St. Helens in Washington are composite cone volcanoes.
Shield volcanoes are built primarily by a series of lava flows that pile one on top of another. Their slopes are seldom more than 10 degrees at the summit and 2 degrees at the base. The Hawaiian Islands are clusters of shield volcanoes. Mauna Loa (on the island of Hawaii) is the world's largest active volcano, rising 13,680 feet (4,170 meters) above sea level. Kenya's Mount Kilamanjaro, the tallest mountain in Africa, is a shield volcano.
Lava domes are made of thick, pasty lava squeezed like toothpaste from a tube. Examples of lava domes are Lassen Peak and Mono Dome in California.
Volcanoes erupt different material, and they each have their own style of erupting. These varied eruptions result from the differences in magma that each volcano contains. Magma that is low in gas and silica (silicon dioxide, a compound found widely in rocks and minerals) yields a gentle flow of thin, quickly spreading lava. In contrast, magma that is rich in gas and silica gives rise to violent explosions: the thick, tarlike magma may plug up the volcanic vent, blocking the upward movement of the magma until built-up pressure blows away the overlying rock. Geologists classify volcanic eruptions according to four chief forms or phases: Hawaiian, Strombolian, Vulcanian, and Peleean.
In a Hawaiian phase, runny lava gushes out in a fountain without any explosive eruptions. In a Strombolian phase (named after the Stomboli volcano on an island north of Sicily), thick lava is emitted in continuous but mild explosions. Lava arcs and steam-driven clouds of ash shower the dome with molten drizzle. A Vulcanian phase occurs when a magma plug has blocked the volcanic vent. The resulting explosive eruption hurls tons of almost solid magma into the sky, and a vapor cloud forms over the crater. The most violent eruption is the Peleean, named after Mount Pelee on the Caribbean island of Martinique. Fine ash, thick lava, and glowing, gas-charged clouds are emitted, traveling downhill at a tremendous speed. This is called a pyroclastic cloud or pyroclastic flow.
When a volcano erupts such a large volume of material, often emptying its magma chamber, the central part of the cone is left unsupported. As a result, the crater and walls of the vent collapse into the hollow chamber, creating a large circular depression known as a caldera across the summit. The famous Crater Lake in southern Oregon formed in this way.
There is lots more information at the referenced site.
http://www.scienceclarified.com/Vi-Z/Volâ¦
How can I correct my friend who stubbornly believes that Global Warming does not exist?
Ron B
He believes that it's a natural order of things, which it is. But he doesn't believe that humans had anything to do with increasing the rate of global warming. He thinks Al Gore invented the theory of global warming. Believe me, he is serious. What kind of proof could I supply him with that you think he may accept? Once he told me that the top NASA scientists don't believe in global warming neither.
Answer
There are some people who will refuse to accept anything if it doesn't conform with their way of thinking - not just global warming but many other issues as well.
I've also met people who think Al Gore invented global warming. I've shown them documents that are over 100 years old that show we know about global warming in the 19th century and they say the documents have been faked. I've shown them TV programs made when Al Gore was 5 years old warming about the dangers of global warming and again, the skeptics claim they've been faked. I've suggested they go to their local library and get books dating back 100 years that warn about global warming, and guess what - they claim these are all fakes as well.
What he's done with the NASA scientist is what some other skeptics do and that is to distort the facts to suit his opinions. Recently a NASA administrator (MIchael Griffin) said he firmly beleived in global warming but didn't see any point in doing anything about it - this is very different to what your friend is saying. It's similar to the claims that are regularly made about Mars warming. These also stem from NASA and have been distorted to suit the skeptics, the reports actually say that parts of Mars are warming, parts are cooling, it's not because of the sun and is unrelated to warming on Earth.
I've done experiments that demonstrate the properties of different gases - show a skeptic that oxygen has no effect on global warming and they beleive you, show them that some gases cause cooling and they beleive you, show them that some gases cause warming and they don't believe you.
Personally I wouldn't worry too much about your friend, let him make up his own mind in his own time. A few years ago most oil companies refuted anthropogenic global warming as did several governments, major organisations and about 30% of the world's population. Today every major oil copmpany in the world accepts global warming as does every single government and recently the CEO's of the world's 1000 leading organisations unanimously declared global warming to be the biggest threat facing humanity, the number of non beleivers has fallen from around 30% to just 8% (16% in the US).
There are some people who will refuse to accept anything if it doesn't conform with their way of thinking - not just global warming but many other issues as well.
I've also met people who think Al Gore invented global warming. I've shown them documents that are over 100 years old that show we know about global warming in the 19th century and they say the documents have been faked. I've shown them TV programs made when Al Gore was 5 years old warming about the dangers of global warming and again, the skeptics claim they've been faked. I've suggested they go to their local library and get books dating back 100 years that warn about global warming, and guess what - they claim these are all fakes as well.
What he's done with the NASA scientist is what some other skeptics do and that is to distort the facts to suit his opinions. Recently a NASA administrator (MIchael Griffin) said he firmly beleived in global warming but didn't see any point in doing anything about it - this is very different to what your friend is saying. It's similar to the claims that are regularly made about Mars warming. These also stem from NASA and have been distorted to suit the skeptics, the reports actually say that parts of Mars are warming, parts are cooling, it's not because of the sun and is unrelated to warming on Earth.
I've done experiments that demonstrate the properties of different gases - show a skeptic that oxygen has no effect on global warming and they beleive you, show them that some gases cause cooling and they beleive you, show them that some gases cause warming and they don't believe you.
Personally I wouldn't worry too much about your friend, let him make up his own mind in his own time. A few years ago most oil companies refuted anthropogenic global warming as did several governments, major organisations and about 30% of the world's population. Today every major oil copmpany in the world accepts global warming as does every single government and recently the CEO's of the world's 1000 leading organisations unanimously declared global warming to be the biggest threat facing humanity, the number of non beleivers has fallen from around 30% to just 8% (16% in the US).
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