Volcanoes

: Volcanic Landforms

• What landforms does lava create on Earth’s surface?

• How does magma that hardens beneath the surface create landforms?

Landforms From Lava & Ash

Shield Volcano

• A wide, gently-sloping mountain made of layers of lava and formed by quiet eruptions

• Example: The Hawaiian Islands

Cinder Cone

• A steep, cone-shaped hill or mountain made of volcanic ash, cinders, and bombs piled of around a volcano’s opening

• Example: Sunset crater in Arizona

Composite Volcano

• A tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials

• Example: Mount St. Helens in Washington and Mount Fuji in Japan

Caldera

• The large hole at the top of a volcano formed when the volcano’s magma chamber collapses

What are the three types of volcanic mountains?

• The three types of volcanic mountains are

• Shield volcanoes• Cinder cone volcanoes• Composite volcanoes

What landforms does lava create on Earth’s surface? Explain how each landform is formed.

• Shield volcanoes– Lava pours out of the volcano’s vent and hardens creating

new layers of rock• Cinder cone volcanoes

– Ash, cinders, and bombs pile up around the volcano vent in a cone-shaped pile

• Composite volcanoes– Quiet eruptions (lava flow) alternate with explosive eruptions

(ash, cinders, and bombs) creating a tall cone-shaped mountain

• Lava plateaus– Lava fills the cracks in Earth creating higher elevated, flat

land

Landforms From Magma

Volcanic Neck

• A deposit of hardened magma in a volcano’s pipe

• Looks like a giant tooth stuck in the ground

Dike

• A slab of volcanic rock formed when magma hardens in a vertical crack

Sill

• A slab of volcanic rock formed when magma hardens in a horizontal crack

Compare and Contrast What is the difference between a dike and a sill?

• Both a dike and a sill form when magma hardens in a crack

• A dike forms when magma hardens into a vertical crack

• A sill forms when magma hardens into a horizontal crack

Batholith

• A mass of rock formed when a large body of magma cooled inside the crust

How does magma that hardens beneath the surface create landforms?

• Volcanic necks– Magma hardens inside the volcano’s pipe

and the softer layer around the pipe wears away

• Dikes– Magma forces its way into vertical cracks in

the crust and hardens

• Sill– Magma squeezes between horizontal layers

of rock and hardens