1. Why do I always take the time to read these when all I do is wonder why I read these …. And now I’m reading this again! Geez … there I go, reading this again!

3. Volcanoes

4. Ag Earth Science – Chapter 10.1
10.1 Vocabulary

5. viscosity
A measure of a fluid’s resistance to flow

6. vent
An opening in the surface of Earth through which molten rock and gases are released

7. pyroclastic material
The volcanic rock ejected during an eruption, including ash, bombs, and blocks

8. volcano
A mountain formed of lava and/or pyroclastic material

9. crater
The depression at the summit of a volcano or that which is produced by a meteorite impact.

10. shield volcano
A broad, gently sloping volcano built from fluid basaltic lava

11. cinder cone
A small volcano built primarily of pyroclastic material ejected from a single vent

12. composite cone
A volcano composed of both lava flows and pyroclastic material
Earth's grandest mountains are composite volcanoes--sometimes called stratovolcanoes

13. caldera
A large depression typically caused by collapse or ejection of the summit area of a volcano

14. Crater Lake
About 6,850 years ago Mount Mazama, a stratovolcano, collapsed to produce Crater Lake, one of the world's best known calderas.
The caldera is about 6 miles (10 km) wide. The catastrophic pyroclastic eruption released about 12 cubic miles (50 cubic km) of magma to the surface.
It was one of the largest eruptions in the last 10,000 years.

15. Mount Shasta
Stratovolcano/Composite Volcano

17. Factors Affecting Eruptions
The primary factors that determine whether a volcano erupts violently or quietly include magma composition, magma temperature, and the amount of dissolved gases in the magma.

18. Factors Affecting Eruptions
Viscosity – a substance’s resistance to flow.
Example – warm maple syrup vs cool maple syrup
Dissolved Gases – During explosive eruptions, the gases trapped in magma provide the force to eject molten rock from the vent.
Vent – an opening to the surface

19. Volcanic Material Lava Flows
Hot basaltic lavas are usually very fluid because of their low silica content.
Silica-rich (rhyolitic) lava is often to slow to be visible. (Sticky- used to make silly putty) Sand and glass are made of Silica

20. Volcanic Material “Pahoehoe” (pah-hoy'hoy') – braids and rope-like
meaning "smooth, unbroken lava")
– braids and rope-like

21. Volcanic Material
“aa” ("ah-ah“) - – rough, jagged blocks (sharp)

22. Volcanic Material Gases
Magmas contain various amounts of dissolved gases
Ex: Water vapor H2O & CO2
Small Amounts of:
Sulfur
Chlorine
Fluorine

23. Volcanic Material Pyroclastic Materials
Pyroclastic material – the name of particles produced in volcanic eruptions
The fragments ejected during eruptions range in size from very fine dust and volcanic ash to pieces that weigh several tons.

24. Types of Volcanoes
The three main volcanic types are shield volcanoes, cinder cones, and composite cones.
Volcano – Repeated eruptions of lava or pyroclastic material often separated by long inactive periods eventually building into a mountain.
Crater – steep-walled depression on the summit of a volcano

25. Types of Volcanoes Shield Volcano
Produced by the accumulation of fluid basaltic lavas. (broad, slightly domed)
Divergent Plate Boundaries
Hot Spots
Usually in Oceans
Created Hawaiian Islands

26. Types of Volcanoes Cinder Cones
Ejected lava fragments the size of cinders, which harden in the air
Explosive

27. Types of Volcanoes Startovolcano/Composite Cones
a large, nearly symmetrical structure composed of layers of both lava and pyroclastic deposits
Convergent Boundaries
Make up the Ring of Fire around the Pacific Ocean
Steep Sided

28. Other Volcanic Landforms
Calderas – a large depression in a volcano
Necks and Pipes – Most volcanoes are fed magma through conduits, called pipes, connecting magma chamber to the surface.

29. Volcano’s Questions What type of rock comes from Volcano's?
What type of plate boundaries cause Volcano’s?
Volcanic eruptions are major cause for when the Earth cools or warms?

30. That’s Random

31. Ag Earth Science – Chapter 10.3
10.3 Vocabulary

32. intraplate volcanism
Igneous activity that occurs within a tectonic plate away from plate boundaries

34. Convergent Plate Boundaries
The basic connection between plate tectonics and volcanism is that plate motions provide the mechanisms by which mantle rocks melt to generate magma.

35. Convergent Plate Boundaries
Ocean-Ocean
Volcanism at a convergent plate where one oceanic slab descends beneath another results in the formation of a chain of volcanoes on the ocean floor.

36. Convergent Plate Boundaries
Ocean-Continent
Volcanism associated with convergent plate boundaries may also develop where slabs of oceanic lithosphere are subducted under lithosphere to produce a continental volcanic arc.

37. Divergent Plate Boundaries
Most magma is produced along the oceanic ridges during seafloor spreading.

38. Intraplate Igneous Activity
Intraplate volcanism occurs within a plate, not at a plate boundary.
Example – Hawaii’s Kilauea volcano.
Most intraplate volcanism occurs where a mass of hotter than normal mantle material called mantle plume rises towards the surface.