Transcript Landforms from Lava and Ash

Volcanic Landforms
6th Grade
2 Kinds of Volcanic Eruptions
• Quiet Eruptions:
– If magma is low in silica
– Lava is low in viscosity and flows easily
• Explosive Eruptions:
– If magma is high in silica
– Lava is high in viscosity and flows slowly
– Explosive eruptions breaks lava into fragments that
quickly cool and harden into pieces of different sizes
like ash, cinders, bombs in a pyroclastic flow
Pyroclastic Flow: when an explosive
eruption hurls out a mixture of hot
gases, ash, cinders, and bombs
• Ash: fine, rocky particles as small as a speck of dust
• Cinders: pebble-sized particles
• Bombs: large particles that range from the size of a baseball
to the size of a car
Volcanic Ash Cloud
• http://www.youtube.com/watch?v=Jav4GLXecQ
Volcanic Eruptions create landforms
made of lava, ash, and other materials.
4 Types of Landforms:
1) Shield Volcanoes
2) Cinder Cone Volcanoes
3) Composite Volcanoes
4) Lava Plateaus
Types of Volcanoes: Composite,
Cinder Cone, and Shield
Shield Volcano
Shield Volcanoes
Shield Volcano
Shield Volcano
Shield Volcano
Shield Volcanoes
Characteristics of a Shield Volcano
• A short, but wide, broad volcano (can be as much as 4 miles wide!)
• Caused by thin layers of basaltic lava with low viscosity
• Caused by quiet eruptions
• has a caldera (large, cauldron-shaped crater) on top
• Hawaiian Islands are made up of shield volcanoes (including Mt.
Kilauea and Mouna Loa –2 of the most active volcanoes in the
world!)
• Very little pyroclastic material
Cinder Cone Volcanoes
Cinder Cone Volcanoes
Cinder Cone Volcanoes
Cinder Cone Volcanoes
Cinder Cone Volcanoes
Cinder Cone Volcanoes
Cinder Cone
Cinder Cone Volcanoes
• A volcano with a steep slope and a large
crater
• Lava has a high viscosity
• Ex. Paricutin in Mexico built up a cinder cone
400 meters high
Composite Volcanoes
Composite Volcanoes
Composite Volcanoes
Composite Volcanoes
Composite Volcanoes
• Tall volcanoes with small craters
• Alternate between quiet eruptions and explosive
eruptions
• Alternate between lavas that contain basalt and
lavas that contain rhyolite
• ex. Mount St. Helens in Washington State and
Mount Fuji in Japan
Composite Volcano
Composite Volcano
Lava Plateaus
• Eruptions of lava that form flat, level areas
• Thin, runny lava flows out of long cracks and
then cools and solidifies
• Ex. Columbia Plateau covers parts of the states
of Washington, Oregon, and Idaho
Lava Plateaus
Lava Plateaus
Lava Plateaus