Download VOLCANOES AND IGNEOUS ENVIRONMENTS

Lesson 602:
VOLCANOES AND IGNEOUS ENVIRONMENTS
Where on Earth do igneous rocks form?
Fundamental Questions
Attempting to give thorough and reasonable answers to the following questions will help you gauge your level of understanding this lesson.
Students that can confidently answer these questions have mastered the concepts of this lesson.
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Why is it difficult to say what the viscosity of lava is?
How do we know what magma is forming underground?
If you had to choose, what kind of volcano would you
be and why?
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Where should you go if you want to see a volcano
erupt?
Where should you go if you don’t want to see a volcano
erupt?
Why does the Earth need volcanoes to erupt?
Lesson Objectives
At the end of this lesson, students should have mastered the objectives listed below.
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Students understand the concept of viscosity and how temperature, gas content, and chemical composition are
mainly responsible for a substance’s viscosity.
Students can give examples of substances that have high viscosities and low viscosities.
Students can match lava type (i.e. basaltic, andesitic, or rhyolitic) to viscosity (i.e. low, medium, or high).
Students can describe the hazards associated with volcanoes.
Students can identify and describe the different types of volcanoes.
Students can identify important locations in the United States that pertain to volcanoes and igneous environments.
Students understand the differences between extrusive and intrusive igneous environments.
Students can identify and describe the different types of intrusive igneous environments.
Students appreciate the role volcanoes play in creating our land, oceans, atmosphere, and climate.
Important Terms
The following terms are some of the vocabulary that students should be familiar with in order to fully master this lesson.
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Aleutian Islands
Andesitic
Ash
Basaltic
Batholith
Caldera
Cascade Mountains
Cinder cone volcano
Cinders
Composite volcano
Crater
Crater Lake NP
Decompression melting
Dike
Extrusive
Flood basalt
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geothermal gradient
Hawaii
Hot Spot
Igneous
Intrusive
Laccolith
Lava
Lava Dome
Magma
Magma chamber
Mauna Loa
Mount Saint Helens
Mudslides
Nuée ardente
Olympus Mons
pluton
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Pyroclastic debris
Pyroclastic flow
Rhyolitic
Ring of Fire
Shield volcano
Sill
Stratovolcano
Vent
Viscosity
Volcanic bombs
Volcanic neck
Volcano
Yellowstone NP
Yosemite NP
Assessment Questions
The following are examples of questions that students should be able to answer. These or similar questions are likely to appear on the exam.
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What factors determine the type of volcanic
eruption?
List the materials ejected from volcanoes.
Describe the 3 main types of volcanoes.
What is a caldera?
* If a pyroclastic flow was traveling at 145 Km/hr,
how long would it take to reach a town that is 2.5
kilometers from the volcano's crater?
Printed on 5/18/2015
6.
How are the locations of volcanoes related to
plate boundaries?
7. What causes intraplate volcanism?
8. What is the Ring of Fire?
9. Which volcanoes are usually the most violent?
10. What is a volcanic neck and how does it form?
11. What are two areas in the United States that lie
over a "hotspot"?
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12. Explain how most magma is theorized to
originate.
13. Why might a laccolith be detected at Earth's
surface before being exposed by erosion?
14. How does the presence of water affect the
melting temperature of a rock?
15. Compare and contrast sills and dikes.
16. What is a pyroclastic flow?
17. Why are the slopes of composite volcanoes
notoriously unstable and prone to landslides?
Related Web Sites
The following are some web sites that are related to this lesson. You are encouraged to check out these sites to obtain additional information.
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http://volcanoes.usgs.gov/
http://en.wikipedia.org/wiki/Volcano
http://www.ready.gov/volcanoes
http://www.enchantedlearning.com/subjects/volcano/
http://volcano.oregonstate.edu/
http://www.weatherwizkids.com/weather-volcano.htm
http://library.thinkquest.org/17457/english.html
Related Book Pages
The following are the pages from your book that correspond to this lesson.
Comprehensive E.S. Book
pp.278-301
Intensive/Honors E.S. Book
pp.470-491
Meteorology/GIS Book
N/A
Massachusetts Standards
The following are the Massachusetts Framework Standards that correspond to this lesson.
Earth Science Learning Standard(s) 3.6, 3.10
What’s Next?
Notes
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DCII.
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VOLCANOES AND IGNEOUS ENVIRONMENTS
A volcano is an opening in the Earth’s crust where magma reaches Earth’s surface.
Causes of Volcanic Eruptions
1. Magma has gases dissolved in it, such as H2O, SO2 (sulfur dioxide), and CO2
2. These gases expand and build up pressure as the magma rises through the lithosphere until finally enough pressure
exists to break through the crust above, releasing the magma and forming a volcano
Types of Volcanic Eruptions
1. lava flows – flow of magma (lava) on the surface of Earth
a. basaltic – dark-colored fine-grained rock (basalt) formed from fast-moving lava containing dissolved gases such
as H2O and CO2
b. rhyolitic – lighter-colored fine-grained rock (rhyolite) formed from slow-moving lava that does not contain much
water; these types of flows are generally extremely viscous; viscosity is a substance’s resistance to flow
c. andesitic – medium-colored fine-grained rock (andesite) formed from intermediate lava
2. pyroclastic debris – molten material ejected from a volcano that cools while in the air and turns to rock before hitting
the ground
a. ash – small, dust-sized particles; 2 mm or less in diameter
b. cinders – pea-sized to golf ball-sized particles
c. volcanic bombs – any particle larger than cinders
3. nuée ardente - fiery pyroclastic flow of ash and gases that moves out from a volcano at speeds up to 125 miles per
hour devastating everything in its path
Three Types of Volcanoes
1. composite volcanoes
a. also called stratovolcanoes because they’re made up of layers, or strata
b. consist of layers of andesitic lava interbedded with layers of pyroclastic debris
c. often have high elevations
d. often have violent eruptions, such as nuée ardentes
e. usually found along convergent plate boundaries; examples of composite volcanoes in the U.S. are Mt. St.
Helens, Mt. Hood, and Mt. Rainier (all on the West Coast)
2. shield volcanoes
a. form from basaltic lava flows that flow easily (low viscosity) and spread across the land surface to form a broad,
gently sloping mound
b. are much broader than they are high
c. generally the largest type of volcano; the shield volcano Mauna Loa, on the island of Hawaii, is likely the largest
volcano on Earth; Olympus Mons, a shield volcano on Mars, is the largest known volcano in the solar system
d. look like a warrior’s shield that is lying on the ground
3. cinder cones
a. steep-sided volcano built up from mainly cinders and other pyroclastic material
b. generally very small compared to other volcano types; less than 300 meters high
c. often form adjacent to composite volcanoes
Features of Volcanoes
1. craters – the hole at the summit of the volcano where lava and pyroclastic debris exit the volcano
2. magma chamber – a giant plume of magma that feeds the volcano; magma chambers are often called batholiths
3. batholith – a large mass of igneous body that forms deep underground melting and deforming the older, surrounding
rocks; batholiths often feed volcanic eruptions
4. caldera – the crater of the volcano when it is larger than 1 Km in diameter
a. the crater often becomes a caldera when the walls of the volcano collapse
b. sometimes the walls of the volcano will almost completely collapse leaving behind nothing but a giant caldera
c. the volcano walls collapse because the magma chamber below becomes empty after the volcano has erupted
5. laccolith – a massive igneous body that forms between two layers of preexisting rock, usually in a dome shape;
smaller than batholiths
6. sill – a small, flat igneous body that forms between the layers of preexisting rocks
7. vent – in addition to the main crater of a volcano, vents may form on the sides of the volcano to allow lava to escape;
cinder cones or smaller volcanoes often form at vent locations
8. dike – a thin intrusion of magma that vertically cuts through the surrounding rock
Page 1 of 2
Crater or Caldera
Vent
F.
Locations of Volcanoes
1. There are about 800 active volcanoes on Earth
2. Volcanoes most often form next to convergent plate boundaries.
a. About 80 percent of all volcanoes are adjacent to convergent plate boundaries
b. About 15 percent of all volcanoes are near mid-ocean ridges (divergent boundaries)
c. The 5 remaining percent form over hot spots; there are about 120 hot spots worldwide
3. Most active volcanoes (60 percent) are found at converging plate boundaries surrounding the Pacific Ocean. The
Pacific Plate is being subducted under the Eurasian Plate, the Indo-Australian Plate, the North American Plate, and
the South American Plate, forming volcanoes at these boundaries. This region is called the Ring of Fire because of
all the volcanic activity.
4. Locations of Volcanoes in the U.S.
a. The Cascade Mountains, which extend from California to Washington State in the U.S. and then into Canada,
are actually volcanoes that formed because of the subduction of the Juan de Fuca plate under the North
American plate. Mt. St. Helens, Mt. Rainier, and Mt. Hood are part of the Cascade Range.
b. The Aleutian Islands of Alaska are actually volcanoes that formed because the Pacific Plate is being subducted
under the North American Plate.
c. Hawaii and the rest of the Hawaiian Islands are volcanoes that formed over a hot spot. Hot spots are places
where magma is close to the surface of the Earth because the mantle is unusually hot in that location.
Yellowstone National Park in Wyoming is also over a hot spot, but the volcanoes there are inactive.
d. There are no volcanoes near New England.
Page 2 of 2
5 killed as Philippine volcano spews rocks 'as big as a living room' - Wor...
1 of 2
http://worldnews.nbcnews.com/_news/2013/05/07/18103402-5-killed-as...
5 killed as Philippine volcano spews
rocks 'as big as a living room'
One of the Philippines' most active volcanoes rumbled to life, killing five climbers. NBCNews.com's Dara Brown reports.
By Hrvoje Hranjski, The Associated Press
MANILA, Philippines -- One of the Philippines' most active volcanoes rumbled to life Tuesday,
spewing room-sized rocks toward nearly 30 surprised climbers, killing five and injuring others who
had to be fetched with rescue helicopters and rope.
The climbers and their Filipino guides had spent the night camping in two groups before setting out
at daybreak for the crater of Mayon volcano when the sudden explosion of rocks, ash and plumes of
smokes jolted the picturesque mountain, guide Kenneth Jesalva told ABS-CBN TV network by
cellphone.
He said rocks "as big as a living room" came raining down, killing and injuring members of his group,
some of whom were in critical condition. Jesalva said he rushed back to the base camp at 3,000 feet
to call for help.
Among the dead were three Germans and their Filipino guide, said Albay provincial Gov. Joey
Salceda. He said everyone on the mountain had been accounted for at midday, except for a foreigner
who was presumed dead.
Eight people were injured, and Salceda said the others were in the process of being brought down the
5/7/2013 1:52 PM
5 killed as Philippine volcano spews rocks 'as big as a living room' - Wor...
2 of 2
http://worldnews.nbcnews.com/_news/2013/05/07/18103402-5-killed-as...
mountain. Ash clouds have cleared over the volcano, which
was quiet later in the morning.
"The injured are all foreigners. ... They cannot walk. If you
can imagine, the boulders there are as big as cars. Some of
them slid and rolled down. We will rappel the rescue team,
and we will rappel them up again," he said from Legazpi,
the provincial capital at the foothill of the mountain.
An Austrian mountaineer and two Spaniards were rescued
with small bruises, he said.
Tuesday's eruption was normal for the restive Mayon, said
Renato Solidum, the head of the Philippine Institute of
Volcanology and Seismology.
The 8,070-foot mountain about 210 miles southeast of
Kit Recebido / EPA
Manila has erupted some 40 times during the past 400
Filipino tour guide Kenneth Jesalva receives
years.
medical attention at a hospital in Albay province,
Philippines, on Tuesday. Jesalva was with a
group when the Mayon volcano spewed ash,
In 2010, thousands of residents moved to temporary
smoke and rocks that killed five mountaineers,
shelters when the volcano ejected ash up to 5 miles from the
officials said. He told ABS-CBN TV by cellphone
crater.
that rocks "as big as a living room" came
raining down on the group.
Solidum said no alert was raised after the latest eruption and no evacuation was being planned.
Climbers are not allowed when an alert is up, and the recent calm may have encouraged this week's
trek. However, Solidum said that even with no alert raised, the immediate zone around the volcano is
supposed to be off limits because of the risk of a sudden eruption.
Salceda said he would enforce a ban on climbers.
Despite the risks, Mayon and its near-perfect cone is a favorite spot for volcano watchers. Most enjoy
the occasional nighttime spectacle of the rim lit by flowing lava, viewing from the safety of hotels in
Legazpi.
The volcano has a trail to the crater that is walkable, though it is steep and strewn with rocks and
debris from past eruptions.
5/7/2013 1:52 PM
Name_____________________
Pack _____________________
Earth Science
Volcanoes and Igneous Environments
Match the features of volcanoes and igneous environments with the correct location on the
drawing below, and then answer the questions.
ash and cinders
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1
2
3
4
5
4
6
7
8
laccolith
crater (caldera)
vent
batholith
sill
cinder cone
dike
lava flow
1. _____________________
9. Which is larger: a batholith or a laccolith?
2. _____________________
3. _____________________
10. Which is larger: a sill or a laccolith?
4. _____________________
5. _____________________
11. What type of volcano is the main volcano in the drawing? HINT: It is not a
cinder cone.
6. _____________________
7. _____________________
8. _____________________
12. Directly above Feature 8 is a rock type that has been folded and warped due
to the hot magma in Feature 8. What type of rock is the folded rock:
igneous, metamorphic, or sedimentary?
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