1. Section 9.3
Volcanic Landforms

2. Notes 9.3 Types of Volcanoes make this chart in your notebook page 203
shield
cinder
Composite
stratovolcano
Size, shape
Draw a diagram
Slope:
Boundary:
TIME to form
LAVA type:
ERUPTION:
Examples:

3. Shield Broad, slight dome shape gently sloping TIME: Slow to form
Divergent, mid-ocean ridge, hot spots 
LAVA: Very fluid – mafic basaltic lava, low gas, low silica (< 50%), low viscosity, high temps. pahoehoe- very little pyroclastic material
Quiet eruptions V.E.I. 0 – 2
Hawaiian Islands are composed of 5 shield volcanoes -Mauna Loa is the largest in Hawaii-Kilauea is the most active, having erupted more than 50 times

4. Cinder cone
Frequently appear in groups around larger volcanoes  at any boundary.
Rather small in size (less than 1000 feet)
Steep slopes (30-40 degrees) form when molten lava is thrown up into the air from a vent and hardens into fragments before coming straight down to the ground  
Forms fast! From months to a few years
 Lava is ejected fragments: ash, cinders, lapilli, pumice, scoria -   - the Paricutin (Mexico City) formed from a cornfield rather quickly (2 years)-

5. Composite Cones
Large, nearly symmetrical mountain structures composed of alternating layers of lava and pyroclastics
Thick, viscous, slow-moving lava,
Felsic / andesitic lava, high silica (70% - more)
Pyroclastic flows: ash, fragments, and steam clouds that race down steep slopes at speeds of 125 mph
Most explosive and violent type of volcano
Around “Ring of Fire”, convergent/subduction, O-O, O-C
Mt. Visuvius,Cascade Range in NW U.S. Mt. St. Helen

6. Pyroclastic Flows

7. Lahar
Mt. St. Helen

8. COMPOSITE VOLCANO Shape: Broad/flat Steep symmetrical
Size: Largest area Highest smallest
Boundary: Convergent Divergent hotspot
Magma: Mafic (basalt) Felsic (rhyolite)
Eruption: Violent/gassy quiet
Other: Pyroclastic flows Pahoehoe lava Cinders/ash

9. (Circle one answer for each category)
SHIELD VOLCANO
(Circle one answer for each category)
Shape Size Plate boundary
Broad/flat Largest area Convergent
Steep Highest Divergent
Symmetrical smallest hotspot
Magma Eruption Other
Mafic (basalt) Violent/gassy Pyroclastic flows
Felsic (rhyolite) quiet Pahoehoe lava
Cinders/ash

10. CINDER CONE Shape: Size: Boundary: Broad/flat Largest area Convergent
Steep Highest divergent
Symmetrical smallest hotspot
Magma: Eruption: other:
(basalt)mafic Violent/gassy Pyroclastic flow
(rhyolite) felsic quiet Pahoehoe lava Cinders/ash

11. Answers: COMPOSITE volcano
Shape: Broad/flat Steep symmetrical
Size: Largest area Highest smallest
Boundary: Convergent Divergent hotspot
Magma: Mafic (basalt) Felsic (rhyolite)
Eruption: Violent/gassy quiet
Other: Pyroclastic flows Pahoehoe lava Cinders/ash

12. Answers: SHIELD VOLCANO
(Circle one answer for each category)
Shape Size Plate boundary
Broad/flat Largest area Convergent
Steep Highest Divergent
Symmetrical smallest hotspot
Magma Eruption Other
Mafic (basalt) Violent/gassy Pyroclastic flows
Felsic (rhyolite) quiet Pahoehoe lava
Cinders/ash

13. Answers:CINDER CONE Shape: Size: Boundary:
Broad/flat Largest area Convergent
Steep Highest divergent
Symmetrical smallest hotspot
Magma: Eruption: other:
(basalt)mafic Violent/gassy Pyroclastic flow
(rhyolite) felsic quiet Pahoehoe lava Cinders/ash

14. Calderas and Lava Plateaus

16. Collapsed cone
A caldera is a bowl-shaped depression or basin at the summit of a volcano
which forms when the summit collapses
after the magma chamber has been mostly emptied after it erupted

18. Mazama started to grow around 400,000 years ago.
Over time much of the c.4000 foot (c.1200 m) depth of the caldera was filled with volcanic material. The rest was filled with water from snowmelt and rain to eventually form Crater Lake.

19. Crater Lake in Oregon

21. At 1,943 feet deep, Crater Lake is the deepest lake in the United States and the seventh deepest lake in the world!

23. Features beneath the surface of Crater Lake constructed using data from the 2000 bathymetry survey. Colors range from orange to blue with increasing water depth.

24. Kilauea caldera

25. Yellowstone National Park is/was a caldera

26. The caldera has been partially filled or “flooded” with lava.

27. Lava plateaus

28. Flood Basalts
When huge volumes of basalt lava erupt rapidly, their flows spread out and no 'volcano' is formed at all - just a huge flat plain of lava flow.
Such huge effusions of lava are moderately common in Earth's past.
The Columbia River Basalts cover 500,000 square kilometers, and are up to 2000 meters thick, for a total volume of near 170,000 cubic kilometers.

29. Layers of igneous rock show evidence of repeated lava flows.

30. A thick layer of basaltic lava that once flooded over the land

31. Obsidian Mountain , WY.

32. World flood basalts

33. Slow, cooled columns of basaltic lava several meters high.

34. Northern Ireland