Take a look at last week’s homework (Page 181, 3 & 4) 3.What causes hot spot volcanoes to form? Magma from deep within the mantle rises and melts through the crust above it, often far from plate boundaries. 4.What will eventually happen to the active volcano on the island of Hawaii, which is now over the hot spot? The volcano will no longer be active as the island of Hawaii moves with the Pacific plate and is carried away from the hot spot.

Lava collects in the crater, the bowl- shaped area that forms around the volcano’s vent. The point on the surface where magma leaves the volcano’s pipe is called the vent. Sometimes magma forces its way out of a volcano through a side vent. Magma that reaches the surface is called lava The river of lava that pours down a volcano and over the land is called a lava flow. A pipe is a narrow, almost vertical crack in the crust through which magma rises to the surface As magma rises toward the surface, it forms a large underground pocket called a magma chamber Magma is extremely hot, molten material that also contains dissolved gases including water vapor THE ANATOMY OF A VOLCANO Think back… Let’s talk about the path magma takes as it rises up through

A.How Magma Forms and Rises 1.Is made in asthenosphere under pressure less dense 2.Magma is less dense than surrounding rock, allowing it to rise to Crust B.Magma and Eruptions 1.Caused by decrease in (or release of) pressure 2.Dissolved gases within magma separate, form bubbles, and are released as lava reaches the surface II. Volcanic Activity

Let’s See a Video Clip that shows Gases Impact on Volcanic Eruptions And now…A familiar comparison

What Are Volcanic Rocks Like? Volcanoes produce lava, which hardens into rock. Some examples of volcanic rock is pumice and obsidian. pumice Observe pumice and obsidian…How would you describe the texture of the pumice? What could have caused this texture. obsidian Now look at the surface of obsidian. How does the surface of the obsidian differ from pumice? What could have produced the difference in texture between the two rocks?

C.Characteristics of Magma 1.Gas Content – Affects the force of Eruption 2.Thickness – Thick = Slow Flow, Thin = Fast Flow 3.Temperature – May determine thickness… a.Greater Temp = Greater Fluidity (Flow) 4.Silica 4.Silica – Material formed from Oxygen and Silicon a.May also determine thickness…

Let’s watch a video that further explains volcanic processes in detail…

Who Wants to Be A Geo-Wiz?

HOMEWORK Read page and the “Social Studies Connection” box on page 188. Index cards for bold vocabulary words found on pages Complete the In Your Journal Assignment on page 188 beneath the “Social Studies Connection” about Pompeii in the Homework Section of your notebook.