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Homework Help: Science: Earth: Volcanoes
Volcanoes are land builders. They created the Hawaiian Island chain. The Earth's crust is broken into broken into pieces called plates. They move across the mantle. The mantle is the layer of the earth located directly under the crust.
Volcanic islands are believed to be formed when boiling hot molten material rises deep from within the mantle and breaks through weak places in the plates as it moves over the hot spot in the mantel. The hot spot always stays in the same place.
Since the volcanoes were created in the ocean, they form what is called a chain of Volcano Islands as their tops reach above the ocean surface.
The role of gas in a volcanic eruption is that it builds up the pressure just below the surface.
The difference between and extinct volcano and a dormant volcano is that when a volcano is calm for years and centuries it is dormant but when a volcano is extinct there has been no volcanic activity for thousands of years.
Volcanoes become extinct by no more gases being produced. Basalt has holes in it so the gas has somewhere to escape.
When scientists are examining volcanoes they have to wear a special breathing apparatus because carbon doixide and sulfur dioxide can be produced from the volcano.
By measuring the temperature and speed of the lava flow, scientists can figure out what is happening inside the volcano.
Volcanoes in australia that have erupted in the last 40 million years:
- Mount Hypipamee
- Piebald
- Mclean
- Undarra
- Toomba
A central volcano is capped with silica, rich in Trachyte and Rhydite. A lava feild is filled with effusive eruptions resulting in little explosive activity. Leucite sites erupt lava and tephra with mineral leucite.
Types of volcanic eruptions:
- icelandic
- hawaiian
- strombolian
- vulcanian
- pelean
- plinian
Homework Help: Science: Earth
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