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Published bySamuel White Modified over 8 years ago
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Plate Tectonics and Mountain Building
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Three most common types of mountains: Fault-block mountains Folded mountains Volcanic mountains
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Formed when rock layers are compressed (squeezed) by horizontal pressure and pushed upward. Usually form at convergent plate boundaries continental/continental Ex. Himalayas
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Caused by tension (stretching) that causes large blocks of the Earth’s crust to fault (break) and then drop relative to each other Formed at divergent boundaries Jagged peaks Ex. Sierra Nevada in California
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Molten rock (lava) erupts onto the Earth’s surface Creates new crust Located at: convergent boundaries Divergent boundaries “hot spots”
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Sometimes called strato volcanoes Formed by alternating layers of lava and rock Their snow-capped peaks often exceed 2500m in height Erupt in explosive way due to viscous magma Mt. Fuji in Japan and Mt. St. Helens are examples
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Built out of layers of runny lava Forms a huge broad shaped, gently sloping cone Eruptions are usually not violent due to basaltic lava Hawaii is an example
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Small volcanic cones usually found on the sides of strato and shield volcanoes Built out of pyroclastic material Eruptions usually do not cause loss of life Grow rapidly and are generally found in clusters They erode quickly due to the material they are made out of
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Magma is mostly made out of silica (a compound of silicon and oxygen) Magma high in silica resists flowing and therefore create violent eruptions Rhyolite magma contains 75% silica and erupts around 700-900 C (1292-1652 F) Magma low in silica flows easily Basalt magma contains 50% silica and erupts around 1200 C (2192 F)
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Produced from silica poor magma Produces lava flows Shield volcanoes produce these types of eruptions
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Have pyroclastic flows with them Do not generally produce lava flows Gases and debris can stay in the atmosphere for years Can change the climate in the area for years
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Lava Flows Knock down, cover, or burn nearly everything in its path Volcanic Ash Can cause roofs to collapse, make roads slippery, clog engines Mudflows Can bury towns Pyroclastic flows Can knock down everything in its path Landslides Can destroy things in its path Can start a Tsunami Steam Explosion Uncommon but can be very devastating
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Effects can last for many years Mudflows can occur years later The new crust that forms is very rich in nutrients Makes wonderful farm land Can make beautiful landscape to live by
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Increasing the amount of carbon dioxide in the air Releases sulfur dioxide into the air which creates acid rain Can change the weather of the world Large amounts of gases and volcanic ash can cause a haze blocking out the sun and lowering the global temperature for years
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Hot springs Magma in the Earth heats water for a hot spring Geyser Some hot springs have enough pressure that they erupt out of the ground Old Faithful in Yellowstone National Park erupts every 35 minutes to 2 hours Fumarole Similar to a geyser but releases steam and other gases Changes in hot springs and fumaroles help predict explosions
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Hot springs that form at spreading centers in the ocean Bring out dissolved minerals and heat Allow sea animals to live where they normally couldn’t
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