Transcript The volcano will no longer be active as the island of Hawaii moves

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.
THE ANATOMY OF A
VOLCANO
Lava collects in the crater, the bowlshaped area that forms around the
volcano’s vent.
Think back…
The point on the surface where magma
leaves the volcano’s pipe is called the
vent.
Magma that reaches the surface
is called lava
Let’s talk about the path
magma takes as it
rises up through
Sometimes magma forces its way
out of a volcano through a side
vent.
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
Magma is extremely hot, molten
material that also contains dissolved
gases including water vapor
As magma rises toward the surface,
it forms a large underground pocket
called a magma chamber
II. Volcanic Activity
A. How Magma Forms and Rises
1. Is made in asthenosphere under pressure
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
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 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 – 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 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.