1. Volcanoes
A volcano is a mountain that forms when molten rock is forced to the Earth’s surface. Volcanoes can by active, dormant, or extinct.

2. Active Volcano…
Kilauea Volcano is presently one of the most active volcanoes on Earth.

3. Dormant “Sleeping” Volcano
Mt. Hood, Oregon
Dormant Volcano: A volcano which is presently inactive but which may erupt again. Most of the major Cascade volcanoes are believed to be dormant rather than extinct.

4. Extinct Volcano Kohala Volcano
Extinct Volcano: A volcano that is not presently erupting and is not likely to do so for a very long time in the future.

5. Where do volcanoes form?

6. Volcanoes form when hot material from below rises and leaks into the crust.
Eventually, but not always, the magma erupts onto the surface. Strong earthquakes accompany rising magma.

7. Parícutin, Mexico, 1943
In the winter of 1943, the countryside near Parícutin, Mexico was rocked by a series of earthquakes. The tremors lasted for nearly two weeks when a fissure open in a farmer's field and the birth of cinder cone was underway. Within 12 hours of the initial eruption, the fissure was ejecting pyroclastic material as well as huge clouds of gas and ash. Lava began to spill from the base of the cone building the volcano laterally.

8. Parícutin, Mexico, 1943
Within 24 hours a 40 meter high cone hurling volcanic bombs several kilometers away had been built.
After nine years of activity, two villages had been buried

11. Anatomy of a Volcano…
Crater- A bowl-shaped depression at the mouth of a volcano
Magma chamber -A large underground pool of molten rock lying under the surface of the earth's crust
Vent - The opening through which the molten rock flows onto the surface.

12. What is the difference between magma and lava??
Lava – molten rock on the earth’s surface.
Magma – molten rock deep inside the earth.

13. II. What erupts from a volcano?
Gases:
Water Vapor, Carbon Dioxide, Sulfur Dioxide, Nitrogen, Hydrogen, Argon
Rock Fragments:
Dust, ash, bombs, and blocks
LAVA!!

14. IV. Types of Lava and Rock Fragments
aa – Sharp, jagged lava
Pahoehoe - Smooth, wrinkled lava

15. Pillow Lava…
Pillow lava – forms on the ocean floor and cools into rounded blobs.

16. Pyro – “fire” Clastic – “Broken”
In Greek:
Pyro – “fire” Clastic – “Broken”
Mt. St. Helens
Mt. Pinatubo
Pyroclastic material - avalanche of hot ash, pumice, rock fragments, and volcanic gas that rushes down the side of a volcano

17. Rock Fragments Lapilli – less than 64 mm in diameter
Volcanic ash – 2 mm in diameter
Volcanic dust - < 0.25 mm in diameter

18. Volcanic blocks – greater than 64 cm in diameter
Volcanic bombs – greater then 64 mm in diameter

19. III. Types of Volcanoes Shield Volcanoes Nonexplosive Thin, runny lava
Gently sloping
Dome-shaped mountains

20. Stratovolcano or Composite
Alternating layers of rock particles and thick lava.
Violent eruptions
Large cone-shaped mountain
Most common type.

21. Cinder Cone Different sizes of volcanic material Explosive eruptions
Large bowl-shaped craters
Steep sides with loose rock particles

22. Mafic Lava
Felsic Lava

23. What type of volcano am I?
Stromboli Volcano in Italy

25. Mt. St. Helens, WA

27. Kanaga Volcano in Alaska

28. Sunset Crater, Arizona

29. Mauna Loa Volcano, Hawaii

30. Water (steam) 77.0%
Carbon dioxide 11.7%
Nitrogen 3.0%
Carbon monoxide 0.5%
Hydrogen 0.5%
Sulfur dioxide 6.5%
Sulfur 0.3%
Chlorine 0.05%
Argon 0.05%