monday, december 7 cinder cones: volcanoes that are steep, but not very big, usually only erupt...
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Monday, December 7Cinder Cones: volcanoes that are steep,
but not very big, usually only erupt once`
Warm-Up: Brainstorm words you think of when you hear, or see, this word
A.500 Active volcanoes on the Earth
A. 500-800 Active volcanoes on the Eartha. Over ½ located around Ring of Fire
i. 50 in the US, third most ii. Indonesia and Japan 1 and 2
iii. Other Countries in the Ring of Fire include: New Zealand, Korea, Philippines, Canada, Mexico, Columia, Costa Rica
b. Most volcanoes are located near plate boundaries
c. Some are located at hot spots- weak spots in the earth’s crust where magma has broken through the mantle Ex: Hawaiian Islands
d. Volcanic Islands form when magma repeatedly hardens on top of an underwater volcano and eventually breaks the surface
e. Active volcano – has erupted in recorded history
f. Dormant volcano – not erupted in recorded history
There are three types of volcanoes. Can you name all 3?
1. Shield Cones
2. Cinder Cones
3. Composite
Broad cone resulting from smooth lava that builds up gradually in layers
Don’t erupt explosively
Lava flows from large opening and surrounding cracks in ground
Ash and loose rock (cinders) spewed out explosively from the volcano
Steeper than shield cones
only about 30-400m tall
Usually only erupts once
Commonly occur in groups or fields
Alternating layers of solidifed lava and rock particles
Larger because volcano erupts explosively sometimes and quietly other times
Tend to erupt explosively because of thicker (more viscous) magma/lava
Thicker magma traps gasses; increases pressure
Shape: steep summit, gently sloping lower part
3 Types of Volcanic Debris
1. Lava
2. Tephra (pieces of rock)
3. Ash
Craters can be created when the walls of a volcano collapse after an eruption
Crater Lake in Oregon was formed that way
Caldera – large crater
Can be more than 30 km (~15 miles) in diameter
Yellowstone National Park is in the middle of a caldera!
Yellowstone has hot springs, bubbling mud, and spouting geysers
Why? Because the region is geologically active!!
We can harness the energy that creates these hot springs and geysers and use it to heat our homes and light our classrooms!
This type of energy is called geothermal energy
Tuesday, December 8
• Plutons: large intrusive igneous rock bodies• Warm-Up:
– List and describe the 3 types of volcanoes– Why are geothermal energy plants often located
near areas with volcanic activity?
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