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 Rises1. Is made in asthenosphere under pressure2. Magma is less dense than surrounding rock, allowing

it to rise to Crust

B. Magma and Eruptions1. Caused by decrease in (or release of) pressure2. 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.

Observe pumice and obsidian…How would you describe the texture of the pumice? What could have caused this texture.

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 Magma1. Gas Content – Affects the force of Eruption2. Thickness – Thick = Slow Flow, Thin = Fast Flow3. Temperature – May determine thickness…

a. Greater Temp = Greater Fluidity (Flow)

4. Silica – Material formed from Oxygen and Silicona. 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 183-186 and the “Social Studies Connection” box on page 188.

• Index cards for bold vocabulary words found on pages 183-186.

• Complete the In Your Journal Assignment on page 188 beneath the “Social Studies Connection” about Pompeii in the Homework Section of your notebook.