Volcanoes. Presented by Kesler Science

Transcription

1 Presented by Kesler Science

2 Essential Questions: 1. What are the parts of a volcano? 2. What are the four types? 3. What processes form volcanoes? 4. Where are volcanoes located on earth?

3 What is a Volcano? A cone-shaped mountain or hill which usually has a crater or depression at the summit Forms around a vent in the earth s crust though which lava, steam, and ash are expelled Can erupt continuously or at irregular intervals Four distinct type of volcanoes

4 Volcano Features Quick Action INB Template Volcano INB Cut out the INB template. Glue it in your INB. Look at the teacher s INB as an example.

5 Volcano Features Volcanoes Features of a Volcano Magma molten rock under the earth s surface Magma Chamber large underground pool of molten rock sitting underneath the Earth s crust. Main Vent the weak point in the Earth s crust where hot magma rises from the magma chamber and reaches the surface. Main Vent Magma/Magma Chamber

6 Volcano Features Volcanoes Volcanic Bombs Main Vent Crater Secondary Cone Secondary Vent Magma/Magma Chamber Features of a Volcano Crater circular basin or depression Secondary Vent magma can reach the surface in other areas Secondary Cone lava builds up here in the shape of a cone Volcanic Bombs large projectiles thrown through the air

7 Volcano Features Volcanoes Features of a Volcano Ash Cloud - small pieces of pulverized rock, minerals, and volcanic glass created during eruption. Pyroclastic Flow - fast-moving current of hot gas and rock that moves away from a volcano Lava molten rock above the earth s surface Volcanic Bombs Pyroclastic Flow Main Vent Ash Cloud Crater Secondary Cone Lava Flow Secondary Vent Magma/Magma Chamber

8 Quick Action INB Template Volcano INB Cut out the INB template. Glue it into your journal along the panel that says glue here Look at the teacher s INB as an example. Composite or Stratovolcano Cinder Cone Volcano Shield Volcano Lava Dome Volcano

9 4 Kinds of Volcanoes Composite Volcano or Statovolcano Cinder Cone Volcano Shield Volcano Lava Dome Let s learn a bit about each type of volcano.

10 Composite Volcano Large symmetrical cones Built by alternating layers of lava flows, volcanic ash, cinders, and bombs. Can create explosive eruptions Examples: Mount Fuji in Japan Mt. Hood, Mt. St. Helens, and Mt. Rainier in the U.S.

11 Cinder Cone Volcano Small cones-shaped volcanoes with steep angled sides Blobs of lava spew into the air during eruptions and fall as cinders on the sides of the volcano Built over a short period of time Examples: Paricutin in Mexico Sunset Crater in Arizona

12 Shield Volcano Profile resembles a warrior s shield lying on the ground Formed by thick lava flows that flow slowly, not explosive Largest volcanoes are shield Examples: Kilauea and Mauna Loa on the Big Island of Hawaii Galapagos Islands

13 Lava Dome Volcano Lava is too thick to flow a great distance. Lava cools and piles up around the vent. As the dome continues to grow it spills loose fragments down the sides. Sometimes occur within craters of other volcanoes Examples: Mt Pelee in Martinique Lassen Peak in California

14 Quick Action Volcanoes Get with a partner at your table and discuss the four different types of volcanoes. What is alike about all of them? What are some differences? Shield Cinder Cone Composite Lava Cone

15 Plate Boundaries Plate Tectonics is the theory that Earth's outer crust (lithosphere) is divided into several plates that glide over the plastic-like and less ridged asthenosphere (upper mantle). It s at the plate boundaries where most of the volcanoes of the world occur.

16 Ring of Fire An active volcanic region Let s find out why volcanoes are active here. What happens when these plate converge and diverge?

17 Converging Boundaries The more dense oceanic crust slides under the continental crust creating a Subduction Zone. Through heat and pressure the oceanic crust melts. This melted crust (because it s less dense than the mantle) works its way to the surface forming volcanoes. Examples: Cascade Mountain Range -OR/WA

18 Converging Boundaries An oceanic crust slides under another oceanic crust creating a Subduction Zone. Through heat and pressure the less dense oceanic crust melts. This melted crust (because it s less dense) works its way to the surface forming a volcanic island arc. Examples: Aleutians Islands in Alaska

19 Diverging Plates Rift Valleys form on land when two continental plates diverge. Active divergent plate boundaries also occur between oceanic plates at the mid-ocean ridges. In both areas volcanoes form. Examples: Rift Valley in Africa Mid-Atlantic Ridge

20 Hot Spot Volcanoes Regions of the mantle that are very hot compared to the surrounding mantle. This creates a mantle plume that eventually breaks through the crust as a volcano. Usually happens in the middle of a plate rather than the boundary Examples: Hawaiian volcanoes

21 Hawaiian Islands Magma rises until it erupts on the seafloor. Hits cold water and hardens into an underwater volcano After many eruptions it breaks the ocean surface. Only the island currently sitting over the hot spot is increasing in size. There is a new island now forming, which has not broken the surface. Plate Movement

22 Quick Action Volcanoes Illustrate how volcanoes are forming at a: 1. Convergent boundaries (oceanic/continental and oceanic/oceanic crusts colliding) 2. Divergent boundaries (oceanic/oceanic and continental/continental crusts diverging) 3. Hot Spots

23 Dormant Volcano Quiet now, but might erupt again Mount Fuji Extinct Volcano Unlikely to erupt again Kohala in Hawaii Active Volcano Have recently erupted Mt. Saint Helens

24 Check for Understanding Can you Identify the features of a volcano? Describe the four types of volcanoes? Describe the proccess that form volcanoes? Locate active volcanoes on Earth?