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=Jav4-GLXecQ

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