1. STARTER 12-1-14 1.Describe how Hawaii was formed by Hot Spots. 2.Describe how Oceanic-Oceanic convergent boundaries create volcanism. 3.Describe how a Continental Volcanic Arc is formed.

2. 10 The Nature of Volcanoes Objectives P. 78 Today you will be able to describe: What determines the type of volcanic eruption? What materials are ejected from volcanoes? What are the three main types of volcanoes? What other landforms are associated with volcanic eruptions?

3. Volcanic eruptions are windows to Earth’s interior. −Provide opportunities to observe processes deep beneath Earth’s surface Why are some volcanic eruptions explosive, while others are quiet? 10 The Nature of Volcanoes

4.  Factors that determine the violence of an eruption Composition of the magma Temperature of the magma Dissolved gases in the magma 10 The Nature of Volcanoes

5. List-Group-Label: Volcanoes

6.  Viscosity Factors affecting viscosity - Temperature (hotter magmas are less viscous) - Composition (silica content) 1.High silica—high viscosity (e.g., flows slowly) 2. Low silica—low viscosity(e.g., flows quick) Viscosity is a material's resistance to flow. Ie. Syrup, water, oil 10 The Nature of Volcanoes

7.  Dissolved gases Mainly water vapor and carbon dioxide Gases expand near the surface: A vent is an opening in the surface through which molten rock and gases are released. trapped in magma and provide the force to extrude molten rock at surface 10 The Nature of Volcanoes

8.  Dissolved gases Violence of an eruption is related to how easily gases escape from magma -Gases escape easily from fluid magma. -Quiet eruption -Viscous (thick) magma slows the upward movement -more violent eruption. 10 The Nature of Volcanoes

9.  Lava Flows Varying flow rates Flow rate – speed at which it moves Dependent upon composition of material 10 The Nature of Volcanoes

10.  Gases Volcanic gases contribute greatly to our atmosphere Volcanic eruptions are: 70% water vapor 15% CO 2 5% N 5% S Trace amounts of Cl, H, Ar 10 The Nature of Volcanoes

11. (Ropy) Lava Flow

12. Slow-Moving Aa Flow (jagged edges)

13.  Pyroclastic Materials Pyroclastic materials name given to particles produced in volcanic eruptions. The fragments ejected during eruptions range in size from very fine dust and volcanic ash to very large. 10 The Nature of Volcanoes

14.  Pyroclastic Materials Types of pyroclastic material - Ash and dust—fine, glassy fragments - Cinders—pea-sized particles Larger Particles - Blocks—hardened lava - Bombs—ejected as hot lava 10 The Nature of Volcanoes Small Particles

17. 10 Types of Volcanoes Objectives P. 80 Today you will be able to describe: What are the three main types of volcanoes? What other landforms are associated with volcanic eruptions?

18. Starter 12/2/14 1.Volcanic eruptions can lead to changes in the local climate. Describe how escaping gases can cause a change in climate. How can it cause air pollution. 2.When viewing magma/lava it gives us an observation as to what is taking place in the mantle. Give your description how this is possible.

19.  The three main volcanic types have their own volcanic history.  Types of Volcanoes 10 Types of Volcanoes More than 26 different types of volcanoes.

20. A conduit, or pipe, carries gas-rich magma to the surface. A crater is the depression at the summit of a volcano A volcano is a mountain formed of lava and/or pyroclastic material.  Anatomy of a Volcano Begin as a fissure or crack in the crust Magma forces it way to surface under pressure 10 Types of Volcanoes

21. Anatomy of a “Typical” Volcano

22.  Shield Volcanoes Shield volcanoes are broad, gently sloping volcanoes built from fluid lavas. Grow from the ocean floor to form islands 10 Types of Volcanoes

23. Shield Volcanoes

24.  Cinder Cones Cinder cones are small volcanoes built primarily of pyroclastic material ejected from a single vent. - Steep slope angle - Rather small in size - Frequently occur in groups May last weeks to years Once stops erupting never erupts again 10 Types of Volcanoes

25. Cinder Cones

26. Composite Cones

27.  Composite Cones Composite cones(stratovolcanoes) composed of both lava flows and pyroclastic material. - Most are adjacent to the Pacific Ocean - Large size - Most violent type of activity - Most active region is Northern and Western Pacific 10 Types of Volcanoes

28. Mount St. Helens Before and After the May 18, 1980, Eruption

29.  Calderas Calderas are large depressions in volcanoes. Formed by collapse Nearly circular 10 Types of Volcanoes

30.  Necks and Pipes Volcanoes are fed through a conduit called a pipe. Cinder cone volcanoes are easily eroded Sometimes leaving crystallized magma behind known as a neck Pipe is connected to the magma chamber 10 Types of Volcanoes

31. low viscosity lava flows covering a wide area.  Lava Plateaus 10 Types of Volcanoes

32.  Plutons are intrusive igneous structures that result from the cooling and hardening of magma. are generally classified according to their shape, size, and relationship to the surrounding rock layers. 10 Types of Volcanoes

33.  Role of Heat Additional heat is generated by The geothermal gradient—Earth’s natural temperature increases with depth but is not sufficient to melt rock in the lower crust and upper mantle - friction in subduction zones - crustal rocks heated during subduction - rising, hot mantle rocks 10 Types of Volcanoes

34. http://www.tulane.edu/~sanelson/Natural_ Disasters/volclandforms.htm

36.  Sills and Laccoliths 10.2 Intrusive Igneous Activity Sills and laccoliths are plutons that form when magma is intruded close to the surface. - Sills resemble buried lava flows and may exhibit columnar joints. - Laccoliths are lens-shaped masses that arch overlying strata upward.

37. Sills Sill

38.  Dikes 10.2 Intrusive Igneous Activity Many dikes form when magma from a large magma chamber invades fractures in the surrounding rocks. Dikes are tabular-shaped intrusive igneous features that cut across preexisting rock layers.

39.  Batholiths 10.2 Intrusive Igneous Activity Batholiths are large masses of igneous rock that formed when magma intruded at depth, became crystallized, and subsequently was exposed by erosion. An intrusive igneous body must have a surface exposure greater than 100 square kilometers to be considered a batholith.

40. Batholiths

41. Types of Igneous Plutons

42.  Geologists conclude that magma originates when essentially solid rock, located in the crust and upper mantle, partially melts. 10.2 Intrusive Igneous Activity  The most obvious way to generate magma from solid rock is to raise the temperature above the level at which the rock begins to melt.

43.  Role of Water 10.2 Intrusive Igneous Activity Causes rock to melt at a lower temperature Plays an important role in subducting ocean plates

44. Basaltic Magma at the Surface

45. STARTER 03/24/11 Answer the reading checkpoint questions on page 290 and 291.

46. 10.2 Review 1.Is the following sentence true or false? Plutons can be studied on Earth’s surface as they form. 2. What three characteristics are used to classify intrusive igneous bodies?

47. 3. when magma from a large magma chamber invades fractures in the surrounding rocks 4. when a large intrusive igneous body of greater than 100 km2 accumulates and becomes exposed 5. when magma is injected between sedimentary layers close to Earth’s surface and collects as a lens-shaped mass 6. when magma is injected along sedimentary bedding surfaces close to Earth’s surface a.Sill b. Laccolith c. Batholith d. dike

48. 7. Is the following sentence true or false? Magma forms when solid rock in the crust and upper mantle partially melts. 8. Circle the letter of one way magma is generated. a. The confining pressure of rocks is increased. b. The water content of rocks is reduced. c. The temperature of rocks is lowered below their melting points. d. The temperature of rocks is raised above their melting points.

49. 9. The rate at which temperature changes with depth below Earth’s surface is called the _______________. 10. How is decompression melting of rocks triggered? 11. ______________rock buried at depth has a much lower melting temperature than does ______________ rock of the same composition and under the same pressure.

50.  The basic connection between plate tectonics and volcanism is that plate motions provide the mechanisms by which mantle rocks melt to generate magma. 10.3 Plate Tectonics and Igneous Activity Rising magma can form continental volcanic arcs (Andes Mountains).  Ocean-Ocean  Ocean-Continent Rising magma can form volcanic island arcs in an ocean (Aleutian Islands).

51. Convergent Boundary Volcano

52.  The greatest volume of volcanic rock is produced along the oceanic ridge system. 10.3 Plate Tectonics and Igneous Activity Less pressure on underlying rocks Lithosphere pulls apart. Large quantities of fluid basaltic magma are produced. Partial melting occurs

53.  Intraplate volcanism is igneous activity that occurs within a tectonic plate away from plate boundaries. 10.3 Plate Tectonics and Igneous Activity The activity forms localized volcanic regions called hot spots. Most intraplate volcanism occurs where a mass of hotter than normal mantle material called a mantle plume rises toward the surface. Examples include the Hawaiian Islands and the Columbia Plateau.

54. Kilauea, an Intraplate Volcano

55. STARTER Complete Map Master Skills Activiy on page 296