Volcanic Landforms
Dana Desonie, Ph.D.
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Printed: September 13, 2014
AUTHOR
Dana Desonie, Ph.D.
www.ck12.org
C HAPTER
Chapter 1. Volcanic Landforms
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Volcanic Landforms
• Identify and describe landforms created by volcanic activity.
Why is the Republic of Indonesia made of 17,508 islands?
Around the Pacific Rim is Indonesia, a nation built from the dotted volcanoes of an island arc. Indonesia is distinctive
for its rich volcanic soil, tropical climate, tremendous biodiversity, and volcanoes. These volcanoes are in Java,
Indonesia.
Landforms from Lava
Volcanoes and Vents
The most obvious landforms created by lava are volcanoes, most commonly as cinder cones, composite volcanoes,
and shield volcanoes. Eruptions also take place through other types of vents, commonly from fissures ( Figure 1.1).
The eruptions that created the entire ocean floor are essentially fissure eruptions.
Lava Domes
Viscous lava flows slowly. If there is not enough magma or enough pressure to create an explosive eruption, the
magma may form a lava dome. Because it is so thick, the lava does not flow far from the vent. ( Figure 1.2).
Lava flows often make mounds right in the middle of craters at the top of volcanoes, as seen in the Figure 1.3.
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FIGURE 1.1
A fissure eruption on Mauna Loa in Hawaii
travels toward Mauna Kea on the Big Island.
FIGURE 1.2
Lava domes are large, round landforms
created by thick lava that does not travel
far from the vent.
FIGURE 1.3
Lava domes may form in the crater of
composite volcanoes as at Mount St. Helens.
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Chapter 1. Volcanic Landforms
Lava Plateaus
A lava plateau forms when large amounts of fluid lava flow over an extensive area ( Figure 1.4). When the lava
solidifies, it creates a large, flat surface of igneous rock.
FIGURE 1.4
Layer upon layer of basalt have created
the Columbia Plateau, which covers more
than 161,000 square kilometers (63,000
square miles) in Washington, Oregon,
and Idaho.
Land
Lava creates new land as it solidifies on the coast or emerges from beneath the water ( Figure 1.5).
FIGURE 1.5
Lava flowing into the sea creates new land
in Hawaii.
Over time the eruptions can create whole islands. The Hawaiian Islands are formed from shield volcano eruptions
that have grown over the last 5 million years ( Figure 1.6).
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FIGURE 1.6
The island of Hawaii was created by
hotspot volcanism.
You can see some
of the volcanoes (both active and extinct)
in this mosaic of false-color composite
satellite images.
Landforms from Magma
Magma intrusions can create landforms. Shiprock in New Mexico is the neck of an old volcano that has eroded away
( Figure 1.7). The volcanic neck is the remnant of the conduit the magma traveled up to feed an eruption.
FIGURE 1.7
The aptly named Shiprock in New Mexico.
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Chapter 1. Volcanic Landforms
Summary
• Landforms created by lava include volcanoes, domes, and plateaus.
• New land can be created by volcanic eruptions.
• Landforms created by magma include volcanic necks and domes.
Explore More
Use this resource to answer the questions that follow.
https://www.youtube.com/watch?v=9UBFSXu9UHY
1.
2.
3.
4.
5.
6.
7.
How many separate eruptions created the basalts at Quincy, Washington?
How thick is the basalt?
When did the lavas begin to erupt?
How do scientists know that the Cascade volcanoes didn’t erupt these lavas?
What type of volcanic vent did the eruptions come from?
What is the origin of all this volcanism?
How are the flows in eastern Washington different from those in Hawaii today?
Review
1. What is Shiprock and how did it form?
2. How do lava plateaus form?
3. What types of landforms are created by very viscous magma?
References
1. Courtesy of DW Peterson/US Geological Survey. A fissure eruption on Mauna Loa in Hawaii travels toward
Mauna Kea on the Big Island. Public Domain
2. User:Brian0918/Wikipedia. Picture of lava domes. Public Domain
3. Courtesy of Willie Scott/US Geological Survey. Lava domes forming in the crater of Mount St. Helens. Public
Domain
4. Kelvin Kay (User:Kkmd/Wikipedia). Layers of basalt created the Columbia Plateau, which is a lava plateau.
Public Domain
5. Vlad and Marina Butsky. Lava flowing into the Pacific Ocean in Hawaii, creating new land. CC BY 2.0
6. Courtesy of NOAA Coastal Services Center Hawaii Land Cover Analysis project. Satellite images is Hawaii,
which was created by hotspot volcanism. Public Domain
7. Bowie Snodgrass. Shiprock in New Mexico, which is the neck of an old volcano. CC BY 2.0
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