Bellringer: What materials are ejected from volcanoes? Quote of the Day: "Science is not belief, but the will to find out." ~Anonymous Sep 26 10:30 AM 1
Copy Directly into your notebook... 1. Pyro Latin and Greek for "fire" or "heat" 2. Clastic means "made from fragments of preexisting rocks" Hence, pyroclastic materials are hot fragments of preexisting rocks that are blown from the vent of a volcano 2
VII. Volcanism A. Volcanic Eruptions 1. Three factors in eruption strength Magma Composition Magma Temperature Dissolved gasses 3
What a good Test Question a. The composition determines the viscosity of the magma. Viscosity is another word for thickness. Thicker magma gives more explosive eruptions b. Gases dissolved gases in magma can add extra energy to an eruption. These are mostly water vapor and carbon dioxide. Think about a bottle of fresh soda vs. a bottle of flat soda. 4
B. Types of Volcanoes 1. Shield Volcanoes are formed by relatively gentle eruptions where the lava flows over a large area. Resemble a warriors shield Examples are Hawaiian Islands and Iceland Big and flat 5
Key Point 2. Cinder Cone Volcanoes are created by a single eruption. After the eruption the volcano never erupts again. a. because of their short life span these volcanoes are relatively small. Steepest type of volcano Usually between 30 40 degree slopes 6
3. Composite Cones are formed from alternating layers of ash and lava. These have the most destructive eruptions Mt. Parinacota in Chile 7
Activity Complete volcano worksheet Name: Period: Use your book starting on page 280 Chapter 10 Section 1 Factors Affecting Eruptions 1. What are three factors that determine how violently or quietly a volcano erupts? 2. Circle the letter of the term that describes lava s resistance to flow. a. temperature b. eruption c. viscosity d. basaltic Volcanic Material 3. Is the following sentence true or false? One thing all volcanic eruptions have in common is that they emit the same amounts of gas. 4. When volcanoes erupt they erupt once and only once.. 5. volcanoes are made of alternating layers of ash and lava and are very tall. 6. These volcanoes have very gentle eruptions and form a very large flattened slope.. a. cinder cone b. shield volcano c. stratovolcano d. composite cone 7. Is the following sentence true or false? Cinder cones are the most potentially dangerous volcanoes because they generate the most explosive eruptions. Other Volcanic Landforms Match each description with its volcanic landform or feature. Description Volcanic Landform or Feature a. Crater b.lava pipe c. Magma chamber d. vent 8. conduit that feeds magma to a volcano s surface 9. Area where magma collects before entering a volcano 10. Cracks in a volcano where gas and lava escape 11. depression formed at the top of a volcano. 12. Sketch a volcano and label the parts. Explain in words the difference in shape between a shield and composite volcano.. 8
C. Volcanic Structures 1. Active Volcanoes are volcanoes that are still being fed magma and have the potential to erupt. 9
2. Structure of an active volcano Sketch and label this diagram in your notes Crater: the depression at the top of a volcano Vent: Location where magma escapes from the volcano. Lava Pipe: Connects the vent to the Magma Chamber Magma Chamber: the source of magma for a volcano 10
3. Dormant Volcanoes no longer have a source of magma and do not have a risk of erupting. a. Dormant volcanoes eventually weather and erode and expose the igneous rocks formed by the magma. These rocks are called Plutons. 11
Lava Necks: The remains of the lava pipe of an ancient volcano. Lava pipes in the Arizona Desert 12
Batholith: When the main magma chamber stops receiving heat from the earth's interior it becomes a solid igneous rock. Laccoliths: Form when magma fills chambers near the surface, but to the side of a volcano. 13
Activity 2 On your volcano sketch Label the parts that will become Lava Necks and Batholiths. 14
4. Calderas form when a magma chamber becomes partly empty and the volcano collapses into the chamber. a. these depressions typically fill with water and form large round lakes. 15
Activity 3 Answer the following: Page 288 1 4 Use the chart on page 281 to answer #6 Complete Sentences 16