Chapter 10, Section 2

1. Chapter 13, Section 2 Chapter 10, Section 2

2. Key Terms Key Terms Create a flashcard for each of the following terms (found on p.325 in your text book). • Mafic • Felsic • Pyroclastic Material • Caldera If you finish early, study your flashcards!

3. Volcanism • Any activity where magma rises to the crust is called VOLCANISM. • Volcanism occurs at mid-ocean ridges, subduction zones, and hot spots.

4. Viscosity • Viscosity= resistance to flow • High Viscosity= honey, syrup • Low Viscosity= water, soda • High Viscosity = more violent eruptions • Low Viscosity = quieter, more flowing eruptions

5. Types of Eruptions

6. Quiet Eruptions • Usually oceanic volcanoes (Hawaii) • Gentle Slopes • Mafic Magma, low viscosity

7. Lava Flows • When mafic lava cools quickly, a crust forms on the surface of the flow. • The crust wrinkles and forms PAHOEHOE=“ropy” • If the lava is more viscous it cools and forms sharp and jagged rock = Aa. • If the lava has a high silica content if cools into blocky lava rock.

8. Explosive Eruptions • Felsic lavas (Mt.St.Helens) contain large amounts of trapped gases • When the volcano erupts the trapped gases escape and send lava and solid particles shooting into the air. • PYROCLASTIC MATERIAL= fragments of rock that form during a volcanic eruption • Steep Slopes

9. Types of Volcanoes

10. Caldera • When the magma chamber empties, the volcanic cone may collapse and leave a large “hole” or CALDERA • Volcanoes with very large eruptions can also cause a CALDERA • Many CALDERAS later fill with water and become lakes.

11. Brainpop-Volcano

12. INTERACTIVE/Assessment • Create a 2-flap book • Label each flap with the following: • Quiet Eruptions • Explosive Eruptions • For each include • Picture • Description/Definition (2 sentences)