1. How do volcanoes change the Earth’s surface?
Volcanic Landforms
How do volcanoes change the Earth’s surface?

2. What you will learn What landforms lava and ash create.
How the magma that hardens beneath Earth’s surface creates landforms.
Other distinct features that occur in volcanic areas.

3. Landforms from lava and ash
Shield volcanoes
Cindercone volcanoes
Composite volcanoes
Lava plateaus

4. Shield Volcano *Lava* Thin layers of lava cool on top of one another
A wide, gently sloping mountain forms gradually over time
Example: Hawaiian volcanoes

6. Cinder Cone Volcano *Lava*
Steep, cone-shaped hill or mountain
Thick lava (high viscosity) builds up in cone producing ash, cinders, and bombs which pile up around vent after it explodes
Example: Sunset Crater in Arizona

8. Cinders and Bombs

9. Composite Volcano *Lava*
Tall, cone-shaped mountains in which layers of lava alternate with layer of ash
Lava flows alternate with explosions
i.e. Stratavolcano
Example: Mount Fuji in Japan and Mount St. Helens in Washington state

11. Quick Check What are the 3 types of volcanoes?
What are the shapes of each?
Which are explosive and which are not?
Which ones have lava?

12. Krakatau Explosion 1883

13. Lava Plateau *Lava*
Thin, runny lava flows out of several long cracks in an area
The lava travels far before cooling and solidifying
Lava flood layers upon lava flood until a raised plateau is formed over millions of years
Example: Columbia Plateau in Washington, Oregon, Idaho

15. Caldera *Lava*
Huge hole caused by the volcano collapsing after explosive eruption empties magma chamber
Crater Lake in Oregon, Mount Mazama
Over time, ash breaks down and releases potassium and phosphorus that plants need. It results in fertile soil.

16. Volcanic Neck *Magma*
Magma hardens in volcano’s pipe, soft rock wears away exposing solid magma
Looks like giant tooth

17. Dike *Magma* Magma that forces itself across rock layers and hardens
Underground, horizontal channels or tubes
Broadens coasts of Hawaiian islands

18. Sill *Magma* Magma squeezes between horizontal layers and hardens
Magma hardens ACROSS the layers.

19. Quick Check What is a caldera?
What way does a dike go, horizontally or vertically?
Which way does a sill go?

20. Batholith *Magma*
Mass of rock formed when magma chamber cools inside crust
Rough, jagged texture after weathering and erosion of land above batholith
Ex: Half Dome in Yosemite National Park

21. Dome Mountain *Magma*
Formed by small bodies of hardened magma which are forced upwards into dome shape

22. Geothermal Activity
Magma a few km beneath earth’s surface heats underground water.
Hot Springs- When groundwater is heated by a nearby body of magma or by a hot rock deep underground.
The hot water rises to the surface and collects in a natural pool.

23. Geysers
When rising hot water and steam become trapped underground in a narrow crack.
Pressure builds until the mixture suddenly sprays above the surface.
A fountain of water and steam that erupts from the ground is a geyser.

24. Geothermal Energy
Water heated by magma can be used as a source of electricity.
Steam from underground is piped into turbines and spins a wheel.
The moving wheel in the turbine turns a generator that changes the energy of motion into electrical energy.
California, New Zealand use it as electricity and Reykjavik, Iceland use this to heat their homes.

25. Quick Check
What’s the difference between a hot spring and a geyser?

26. Can you guess the type of landform?

27. Indian Head Mountain, Montana

28. Laccolith at Fresno Canyon, north of Lajitas
Laccolith at Fresno Canyon, north of Lajitas. Big Bend National Park, Texas. Photo credit: USGS Digital Data Series DDS-21 CD-ROM

29. Photograph by J.D. Griggs on 16 July 1990

30. Before the eruption
After the eruption

31. photo by Tibi Marin
“Magma Boulders”

32. John Day region in Oregon

33. Devil's Tower, WY Shiprock, New Mexico
Shiprock, New Mexico

34. United States
India

35. Mount Aso vents a large cloud of steam at
Japan's Aso National Park.

36. Belknap Volcano, Oregon
USGS Photograph taken on October 1, 1984, by Lyn Topinka

37. Sill can be seen as the dark layer of rock to the left of the snow field. Glacier National Park. Photo credit: USGS Digital Data Series DDS-21 CD-ROM

38. Dike on south side (left) of Shiprock, a volcanic neck, in the distance. Photo credit: USGS Digital Data Series DDS-21 CD-ROM

40. Pu`u `O`o Eruption on Flanks of Kilauea, Hawaii
Photograph by C. Heliker on 2 June 1986

41. Olympus Mons:
One hundred times larger than Mauna Loa

42. The Moon
Many craters on Earth’s moon were believed to be filled by lava flows.

43. Venus
This picture (mapped via radar in 1994) show the immense extent of Venus's volcanism. She has more in the way of lava flows than the Earth has rivers.
Copyright © Dr B.M.Gunn

44. Volcanoes on Io This image shows what it might look like standing on the surface of
Jupiter's moon, Io. A smoldering volcano can be seen against the large
image of Jupiter. Smoke added with Photoshop.
Background image of Jupiter is a Cassini spacecraft image taken in 2001
while flying by Jupiter on its way to Saturn (Credit: NASA/JPL/University of Arizona).

45. Neptune's Largest Moon Credit: Voyager 2, NASA
Triton:
Neptune's Largest Moon Credit: Voyager 2, NASA
The above picture of Triton was taken in 1989 by the only spacecraft
ever to pass Triton: Voyager 2. Voyager 2 found fascinating terrain, a
thin atmosphere, and even evidence for ice volcanoes on this world of
peculiar orbit and spin.

46. Geysers on Triton Credit: NASA, Voyager Project,
Copyright Calvin J. Hamilton
Frozen, Solid Nitrogen!!!
Explanation: In August of 1989 NASA's Voyager 2 spacecraft passed by Neptune,
the most distant of the solar system's gas giant planets. Its encounter with Neptune
climaxed with its closest approach to Neptune's largest moon Triton. From a distance
of about 24,000 miles the robot space probe surveyed Triton's surface, whose
temperature averages nearly -400 degrees Fahrenheit (-240 degrees C), and discovered surprising
evidence of a complex and active world. For example, the prominent dark streaks
in this image seem to come from small volcanoes and may consist of nitrogen frost
mixed with organic compounds ejected during geyser-like eruptions.

47. Image Credits
Belknap84_belknap_shield_volcano_ jpg Belknap Shield Volcano, Oregon. View from McKenzie Pass. USGS Photograph taken on October 1, 1984, by Lyn Topinka.