PPT-Shield Volcanoes

Basaltic Lava low silica content low viscosity low gas content Hot spots magma moves up from lower mantle and plates move over it Ex Hawaii note see video on favorites Shield Volcanoes. Yellowstone Park is not only spectacular but also unique. It is the result of three volcanic eruptions, the likes of which have never been seen in all of recorded history. The first eruption occurred 2 million years, followed by two more eruptions 1 million years and 600,000 years ago. Below Yellowstone Park there is a hot spot that is generating basaltic magma. At the time of each of their three eruptions, the magma chamber began to produce large volumes of basaltic magma. Because of its low viscosity, the basaltic magma quickly rose to the bottom of the granitic continental crust. However, because the density of basaltic magma (density about 3) is slightly higher than that of granite (density about 2.9) it could not force its way through the granite to the surface. Instead, it began to pool beneath the granitic crust. The amount of heat trapped within the molten basaltic magma was enough to melt the minerals making up the overlaying and surrounding granite, forming a growing mass of granitic magma. Granitic magma is highly viscous and extremely gas-charged. Although it rose only very slowly, the granitic magma advanced upwards by melting even more of its own overlying granitic rock. At some point, radial fractures began to form around the rising mass of granitic magma. These fractures allowed steam eruptions to vent gas. Shortly after, with the overlying granitic rock severely weakened by the fractures, the highly gas-charged granitic magma erupted. The land to a distance of 200 miles in all directions was decimated. Pyroclastic flows, the most destructive eruptive features known, swept across the countryside. Ash fell across the country from the eruption site to the Atlantic Ocean. Ash polluted the world’s atmosphere, blocked the energy of the Sun, and plunged the Northern Hemisphere into a frozen wasteland for years. Can such an eruption occur in the Yellowstone region again? All the evidence suggests that the magma chamber below Yellowstone Park is current rising. According to the director of the Yellowstone Volcanic Observatory, it is not a question of whether or not another super-eruption CAN happen; it’s a question of WHEN it will happen!. There Are Three. Types of Volcanoes. Shield. Cinder. Composite. Shield. Shield Volcanoes are: . Usually Low. Gentle Slope. Wide Base. Let’s Compare. Low. Gentle Slope. WIDE BASE. YEP! IT’S A SHIELD VOLCANO. There are 3 types of volcanoes:. Shield – VERY large. Composite – medium. Cinder - small. Differences between volcanoes. Origin. Where does magma come from?. Shield – Basaltic magma forms deep down. . . Here we will compare extrusive and intrusive volcanic features and action. q distinguish magma from lava. q identify intrusive and extrusive igneous features (e.g., sill, dike, . batholith. 1.Mantle. 2.. Lithosphere. 3. Outer Core. 4. Inner Core. How compressional forces are caused. . Compressional / Destructive. (subduction zones) plate boundaries occur when an oceanic plate is forced under (or subducts) a continental plate . Mountain. A large landform that stretches above the surrounding land in a limited area.. Mountains are formed through tectonic forces or volcanism. . Height from the . surface of the earth by over . A volcano is a fault in earth’s crust that allows magma to escape.. We call the release of magma an eruption.. How does that work?. Magma is the layer of melted rock that . lies just below earth’s crust.. 1. . A . volcano is a fault in earth’s crust that allows magma to escape.. 2. . We . call the release of magma an eruption.. How does that work?. 3. . Magma . is the layer of melted rock that . lies just below earth’s crust.. 8. th. . Grade Science. Earth. ’. s crust is made up of huge slabs called . plates. , which fit together like a jigsaw puzzle. These plates sometimes move.. Between the Earth. ’. s crust and the . Compare the features of volcanoes.. Describe the stages in volcano formation.. What are Volcanoes?. Volcanoes are vents through which molten rock and gas escape from a . magma chamber.. Volcanoes can differ. 1. An opening in Earth’s crust through which molten rock, ash and gases erupt.. 2.Volcano: The landform that develops around the opening.. 3. A way for Earth to release heat energy from the interior due to radioactive decay.. Volcanoes. Shield. Composite. Cindercone. There are . three. types of volcanoes:. Formed by layer after layer of lava.. Usually have low silica content, and gases can escape easily.. Has quiet eruptions.. Volcanoes. Volcano:. mountain that forms in Earth’s crust when molten material (magma) reaches the surface. . Remember, . magma . is molten rock below ground; . lava. is molten rock at the surface. . About 1500. Bellringer. Begin volcano video and questions. Objective. Pick one way to trigger a tsunami (1). Include one real life example (1). Describe how a tsunami wave is different from a wind wave (2).