Presentation on theme: "Open your binder to the notes section. Prepare to take notes"— Presentation transcript:
1 Open your binder to the notes section. Prepare to take notes 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.
2 Three Types of Volcanoes Shield VolcanoWide, gently sloping mountainLayers of lava pour from the vent and harden on top of a previous layerCinder Cone VolcanoSteep (high), cone-shaped hill or small mountainComposite VolcanoLava alternate with explosive eruptions of ash, cinder, and bombs.Tall, cone-shaped mountains in which layers of lava alternate with layers of ash
3 3 Types of Volcanoes Shield Volcano Built out of layers of runny lava Gently sloping sides
4 3 Types of Volcanoes Cinder Cone Volcano made of layers of pyroclastic materialErode quickly
5 3 Types of Volcanoes Composite Volcano Sometimes called a stratovolcanoForms from pyroclastic material and pouring lavaSteep sides
6 Below are cross-sections of each of the different kinds of volcanoes. cinder cone volcanocomposite or stratovolcanoshield volcano
9 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.
10 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.
11 VolcanoesA volcano is a weak spot in the crust where molten material, or magma, comes to the surfaceThe crust is fractured (broken), allowing magma to reach the surfaceMagma is a molten mixture of gases and water from the mantleThe Ring of Fire formed by volcanoes and earthquakes around the rim of the Pacific OceanMost volcanoes are found along plate boundariesA hot spot is an area material rises from deep within the mantle and melts to form magma; volcanoes form above the hot spot
13 Kinds of Eruptions There are two kinds of eruptions: 1. Explosive 2. NonexplosiveExplosiveExplosive eruptions break lava into fragments (pieces)Gases and pressure build up until they explodeThe magma has a high silica content (silica is made up of silicon and oxygen)Pyroclastic flow- explosive eruption throws hot gases, ash, cinders and bombsNonexplosiveVolcano erupts quietly and oozes outThe magma has a low amount of silica
16 Inside A Volcano Magma chamber- magma collects Pipe- magma move up through this channelVent- magma and gas move up through an openingLava flow- area covered by lava as it pours out of a ventCrater- bowl-shaped area that may form at the top of a volcano around the central ventA caldera is a huge hole left by the collapse (fall) of a volcanic mountainPieces of the volcano fall inward
22 HistoryThe 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.
23 TiltmeterScientists 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.
24 Gas EmissionsAnother 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.
25 Review Questions What is a volcano? What is occurring at the Pacific Ring of Fire?What is a hot spot?What feature forms at a hot spot?Explain the difference between an explosive and nonexplosive eruption.
26 Review Questions 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.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.
28 Review Questions 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.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.What is a hot spot?A hot spot is an area where magma rises.What feature forms at a hot spot?Volcanoes form above hot spots.
29 Energy Inside EarthIn a hot spring, hot water and (rocks, gases) escape from the ground.In a geyser, the hot water and steam (shoot, flow) out of the ground.Geothermal energy can be used to heat home and to produce (noise, electricity).Hot springs are sources of (solar, geothermal) energy.