Volcanoes

Do Now 11/12/13

1. What is magma?

2. At which type of plate boundary are volcanoes most common?

3. Which mineral is the hardest? The softest?

4. What is the difference between a clastic sedimentary rock and an organic?

Do Now 11/13/13

1. What is density?

2. How does density affect plate movement?

3. How does density affect the layers of the Earth?

4. How does density affect the formation of volcanoes?

Do Now 11/12/131. When plates move together they form a

________________ boundary.

2. When plates move apart they form a ___________________ boundary.

3. When plates slide past each other they form a ____________ boundary.

4. The theory that plates were once joined in a supercontinent is called _______________.

Do Now 12/3/121. Human Activity: The natural movement of

sediment from one place to another is called _______.

2. Pollution: Water pollution is caused by __________.

3. Natural Resources: A natural resource that cannot be reused or replaced quickly.

4. Waves: The distance between the crest and trough of a wave is called the _________.

1) What is a volcano?• A mountain that forms when molten rock

(magma) is forced to the Earth’s surface.

Mt. Saint Helens, WashingtonLast Eruption 2008

Pavlof Volcano, AlaskaLast Eruption 2007

Active Volcanoes of the World

2) What are the parts of a volcano?

• Magma Chamber –large underground pool of molten rock.

• Main Vent – where hot magma has reached the surface.

• Crater – a funnel shaped pit at the top of the volcano.

• Ash Cloud – gas and small pieces of pulverized rock.

2) What are the parts of a volcano?

• Lava – Molten rock above the Earth’s surface.

• Pyroclastic Material – rock fragments, ash, gas released during eruption.

• Side Vent – secondary place where lava escapes the volcano.

3) What are the three types of volcanoes?

Shield Composite

Cinder Cone

Shield Volcanoes• Formed from runny lava and basalt• Non explosive eruptions• Gentle sloping sides• Wide base• Forms underwater

Examples of Shield Volcanoes

• Hawaiian Islands

Cinder Cone Volcanoes

• Made of pyroclastic material

• Explosive eruptions

• Steep sides

• Narrow base

• Found in clusters

• Erode quickly because there is no lava to cement rocks together

Examples of Cinder Cone Volcanoes

• Paricutin - Mexico

Composite Volcanoes

• Made from alternating layers of lava and pyroclastic material

• Non explosive and explosive eruptions

• Steep sides

• Wide base

• Also called Stratovolcano

Example of Composite Volcano

• Mount Hood, Oregon

4) What is a non explosive volcano?

• A volcano that produces lava flows.

5) What is an explosive volcano?

• Volcanoes that blast out gas, rock, ashes/dust, and superheated steam.

6) What determines if a volcano is explosive or non explosive?

• The composition of the magma determines what type of eruption.

- Explosive volcanoes have more water and silica.

7) What is a caldera?

• A circular depression that forms when a magma chamber empties and causes the ground above it to sink.