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Open your binder to the notes section. Prepare to take notes. Head your notes and copy the standard below. Open your binder to the notes section. Prepare to take notes. Head your notes and copy the standard below. S6E5e- Explain the effects of physical processes (such as plate tectonics, erosion, deposition, volcanic eruptions, gravity) on geological features.
Three Types of Volcanoes Shield Volcano –Wide, gently sloping mountain –Layers of lava pour from the vent and harden on top of a previous layer Cinder Cone Volcano –Steep (high), cone-shaped hill or small mountain Composite Volcano –Lava alternate with explosive eruptions of ash, cinder, and bombs. –Tall, cone-shaped mountains in which layers of lava alternate with layers of ash
3 Types of Volcanoes Shield Volcano –Built out of layers of runny lava –Gently sloping sides
3 Types of Volcanoes Cinder Cone Volcano –made of layers of pyroclastic material –Erode quickly
3 Types of Volcanoes Composite Volcano –Sometimes called a stratovolcano –Forms from pyroclastic material and pouring lava –Steep sides
Below are cross-sections of each of the different kinds of volcanoes. cinder cone volcano composite or stratovolcano shield volcano
EFFECTS OF VOLCANIC ERUPTIONS ON THE EARTH
VOLCANIC HAZARDS TO THE EARTH
GEOLOGICAL CHANGES TO THE EARTH Craters and Calderas When a volcano explodes, much of the rocks and debris are blown from the top of the volcano. This is called a crater. If a great deal is blown off and the magma chamber below the volcano empties itself of all its magma, then the top of the volcano caves in on itself and the earth all around the volcano sinks. This is how calderas are created.
LAVA PLATEAU lava plateaulava plateau is a geological landform that is created when large amounts of runny lava leak from large cracks in the earth called fissures. The lava may run and spread evenly over large areas of land to create a unique look. Two examples of lava plateaus in the United States are Lassen National Park in California, and the Columbia River Plateau in Washington.
Volcanoes A volcano is a weak spot in the crust where molten material, or magma, comes to the surface –The crust is fractured (broken), allowing magma to reach the surface Magma is a molten mixture of gases and water from the mantle The Ring of Fire formed by volcanoes and earthquakes around the rim of the Pacific Ocean Most volcanoes are found along plate boundaries A hot spot is an area material rises from deep within the mantle and melts to form magma; volcanoes form above the hot spot
Ring of Fire
Kinds of Eruptions There are two kinds of eruptions: 1. Explosive 2. Nonexplosive Explosive Explosive eruptions break lava into fragments (pieces) Gases and pressure build up until they explode The magma has a high silica content (silica is made up of silicon and oxygen) Pyroclastic flow- explosive eruption throws hot gases, ash, cinders and bombs Nonexplosive Volcano erupts quietly and oozes out The magma has a low amount of silica
Eruptions Explosive –Pyroclastic material Nonexplosive –Flowing lava
Inside A Volcano Magma chamber- magma collects Pipe- magma move up through this channel Vent- magma and gas move up through an opening Lava flow- area covered by lava as it pours out of a vent Crater- bowl-shaped area that may form at the top of a volcano around the central vent A caldera is a huge hole left by the collapse (fall) of a volcanic mountain –Pieces of the volcano fall inward
Cinder Cone & Volcanic Bombs
History The first thing scientists do is determine a volcano's eruption history. A volcano is classified as active, dormant or extinct based upon when it has last erupted. Active volcanoes are in the process of erupting or show signs of eruption in the very near future. Dormant volcanoes are "sleeping." This means they are not erupting at this time, but they have erupted in recorded history. An extinct volcano has not erupted in recorded history and probably will never erupt again.
Tiltmeter Scientists also have an instrument that they attach to the side of volcanoes. It is called a tiltmeter. A tiltmeter will detect small changes in the slope of a volcano because as a volcano is about to erupt, the earth may bulge or swell up a bit.
Gas Emissions Another thing scientists look for is the amount and types of gasses that are emitted from a volcano. When a volcano is close to erupting, the gasses become more pronounced. There is a slight problem with depending upon only gas emissions to predict eruptions, however. Sometimes lava will leak up through the top of a volcano and harden quickly.
Review Questions 1.What is a volcano? 2.What is occurring at the Pacific Ring of Fire? 3.What is a hot spot? 4.What feature forms at a hot spot? 5.Explain the difference between an explosive and nonexplosive eruption.
Review Questions 1.What is a volcano? A volcano is a weak spot in the crust where molten (hot, melted) material or magma comes to the surface. 2. What is occurring at the Pacific Ring of Fire? Volcanoes, mountain ranges and earthquakes are forming along plate boundaries. 3. What feature forms at a hot spot? Volcanoes form above hot spots. 4.What is a hot spot? A hot spot is an area where magma rises. 5. Explain the difference between an explosive and nonexplosive eruption. Gases and pressure cause lava to break into fragments and pyroclastic material to be thrown from the volcano during an explosive eruption. Lava oozes out slowly and more quietly during a nonexplosive eruption.
Review Questions 1.What is a volcano? A volcano is a weak spot in the crust where molten (hot, melted) material or magma comes to the surface. 2. Where are most volcanoes located? Most volcanoes are found along plate boundaries. 3.What causes volcanoes to form at a divergent boundary? The plates separate and magma pushes up to the surface. The magma cools and hardens. Over time a volcano forms. 4.What is a hot spot? A hot spot is an area where magma rises. 5.What feature forms at a hot spot? Volcanoes form above hot spots.
Energy Inside Earth 1.In a hot spring, hot water and (rocks, gases) escape from the ground. 2.In a geyser, the hot water and steam (shoot, flow) out of the ground. 3.Geothermal energy can be used to heat home and to produce (noise, electricity). 4.Hot springs are sources of (solar, geothermal) energy.