Table of Contents Volcanoes and Plate Tectonics Properties of Magma Volcanic Eruptions Volcanic Landforms

Volcanoes and Plate Boundaries - Volcanoes and Plate Tectonics Volcanoes and Plate Boundaries Volcanic belts form along the boundaries of Earth’s plates.

Volcanoes and Plate Boundaries - Volcanoes and Plate Tectonics Volcanoes and Plate Boundaries Volcanoes often form where two oceanic plates collide or where an oceanic plate collides with a continental plate. In both situations, an oceanic plate sinks through a trench. Rock above the plate melts to form magma, which then erupts to the surface as lava.

Hot Spot Volcanoes - Volcanoes and Plate Tectonics A volcano forms above a hot spot when magma erupts through the crust and reaches the surface.

Asking Questions - Volcanoes and Plate Tectonics Before you read, preview the red headings. In a graphic organizer like the one below, ask a where, what, or how question for each heading. As you read, write the answers to your questions. Questions Answers Where are volcanoes found? Most volcanoes are found along plate boundaries. What are hot spots? A hot spot is an area where material from deep within the mantle rises and then melts, forming magma.

Magma Composition - Properties of Magma Magma varies in composition and is classified according to the amount of silica it contains. The graphs show the average composition of the two types of magma. Use the graphs to answer the questions.

Magma Composition - Properties of Magma Reading Graphs: Study both graphs. What materials make up both types of magma? Silica, other oxides, and other solids.

Magma Composition - Properties of Magma Reading Graphs: Which type of magma has more silica? About how much silica does this type of magma contain? Rhyolite-forming magma; about 70 percent.

Magma Composition - Properties of Magma Estimating: A third type of magma has a silica content that is halfway between that of the other two types. About how much silica does this type of magma contain? About 60 percent

- Properties of Magma Magma Composition Predicting: What type of magma would have a higher viscosity? Explain. Rhyolite-forming magma would have higher viscosity because it is higher in silica.

Silica- (glass, quartz – most of the crust ) A compound that contains the two elements Si (silicon) and O (oxygen)- SiO2

Viscosity Viscosity is a measure of the resistance of a fluid to flow. In everyday terms (and for fluids only), viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick",

Identifying Main Ideas - Properties of Magma Identifying Main Ideas As you read the section “Types of Viscosity of Magma,” write the main idea in a graphic organizer like the one below. Then write three supporting details that further explain the main idea. Main Idea Magma’s viscosity depends on its physical and chemical properties. Detail Detail Detail Magma is made of elements and of compounds, among them silica. Viscosity is a property of magma. Viscosity depends on silica content and temperature.

Links on the Properties of Magma Click the SciLinks button for links on the properties of magma.

End of Section: Properties of Magma

Magma Reaches Earth’s Surface - Volcanic Eruptions Magma Reaches Earth’s Surface When a volcano erupts, the force of the expanding gases pushes magma from the magma chamber through the pipe until it flows or explodes out of the vent.

Composite Volcano Eruption Activity - Volcanic Eruptions Composite Volcano Eruption Activity Click the Active Art button to open a browser window and access Active Art about composite volcano eruption.

Kinds of Volcanic Eruptions Within the last 150 years, major volcanic eruptions have greatly affected the land and people around them.

Using Prior Knowledge - Volcanic Eruptions Before you read, look at the section headings and visuals to see what this section is about. Then write what you know about volcanic eruptions in a graphic organizer like the one below. As you read, write what you learn. What You Know Lava flows out of a volcano. Eruptions are not all the same. Some volcanoes are dormant. What You Learned Magma rises toward Earth’s surface through a pipe that leads to a vent. Differences in gas and silica content cause some eruptions to be explosive and others to be quiet. Dormant volcanoes can become active at any time.

End of Section: Volcanic Eruptions

Landforms From Lava and Ash - Volcanic Landforms Landforms From Lava and Ash Volcanic eruptions create landforms made of lava, ash, and other materials. These landforms include composite volcanoes, shield volcanoes, cinder cone volcanoes, and lava plateaus.

Landforms From Lava and Ash - Volcanic Landforms Landforms From Lava and Ash A caldera forms when an volcano’s magma chamber empties and the roof of the chamber collapses. The result is a large, bowl-shaped caldera.

Landforms From Magma - Volcanic Landforms Features formed by magma include volcanic necks, dikes, and sills, as well as batholiths and dome mountains.

Batholiths - Volcanic Landforms A batholith is a mass of rock formed when a large body of magma cools inside the crust. Several large batholiths form the core of mountain ranges in western North America. Half Dome in Yosemite National Park, California, is part of the Sierra Nevada batholith.

Outlining - Volcanic Landforms As you read, make an outline about volcanic landforms that you can use for review. Use the red headings for the main topics and the blue headings for the subtopics. Landforms From Lava and Ash Shield Volcanoes Cinder Cone Volcanoes Composite Volcanoes Lava Plateaus Calderas Soils From Lava and Ash Landforms From Magma Volcanic Necks, Dikes and Sills Dikes and Sills Batholiths Dome Mountains Geothermal Activity Hot Springs Geysers Geothermic Energy

Links on Volcanic Effects - Volcanic Landforms Links on Volcanic Effects Click the SciLinks button for links on volcanic effects.

End of Section: Volcanic Landforms

Graphic Organizer Shield volcanoes Cinder cones Ash, cinders, and bombs Lava and ash

End of Section: Graphic Organizer