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Volcanoes
Magma
29
Science
7th Grade
11/09/2007

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Term
Volcano
Definition

 

opening in the Earth's crust

where lava, ash come through

Term
Magma
Definition
molten rock under Earth's surface
Term
Lava
Definition

very hot melted rock that comes out of a volcano

above the Earth's surface

Term
Ring of Fire
Definition

Many volcanoes around the Pacific Ocean

plate boundaries

Term
Hot spot
Definition
place in the upper mantle where magma comes up and forms a volcano
Term
Active Volcano
Definition
live,one that is erupting
Term
Dormant Volcano
Definition
sleeping, can become active
Term
Extinct Volcano
Definition
dead,not likely to erupt again
Term
Hot spring
Definition
place,where water is naturally heated by earth's interior
Term
Crater
Definition
bowl-shaped area forms at top of volcano
Term
Types  of Eruptions
Definition

1. Explosive

2. Quiet

Term
Where do volcanoes happen?
Definition

-near boundaries of plates

-along edge of continents

-islands arcs

-along mid ocean ridges

Term
How do volcanoes erupt?
Definition

-quietly

-explosively

Term
three (3) types of volcanoes
Definition

-shield volcano

-cinder cone

-composite

Term
parts of a volcano
Definition

-lava

-crust

-ash cloud

-magma chamber

conduit

-side vent

-vent

Term
causes of eruption
Definition

1. liquid magma is less dense than the surrounding crust and rises

2. as magma rises, pressure decreases

3. a decrease in pressure allows dissolved gases in the magma to separate out

4. gases rush upward carrying the magma with them

Term
location
Definition

1. plate boundaries (Ring of Fire)

 

2. Hot spots (Hawaii)

Term

shield volcanoes

Definition

1.Quiet eruptions

2. Thin, runny, fluid lava

3. Low in silica, extremely hot

4. gently sloped dome shape

5. Largest of volcanoes-up to 28, 000 feet tall

6. Example: Hawaiin volcanoes (Mauna Loa, Mauna Kea, Kilauea)

Term
Cinder cones
Definition

1. Explosive eruptions

2. Lava is thick, cinders and ash

3. High in silica, cooler than fluid lava

(but still extremely hot)

4. Steep sided cone shape

5. Smallest of volcanoes-usually no higher than

1000 ft

6. Example: Paricutin

Term
Composite volcaoes
Definition

1. Alternating between explosive and quiet eruptions

2. Lava alternates between thick cinders/ash and thin layers of fluid lava

3. High in silica, cooler than cooler than fluid lava

(but still extremely hot)

4. Steepsided symmetrical cone shape

5. Size - up to 8000 ft

6. Examples: Mt. Fuji (Japan), Mt. St. Helens and Mt. Rainier (Washington State)

Term
types of Volcanoes
Definition

1. Active

2. Domant

3. Extinct

Term
Volcanic Landforms
Definition

1. Lava plateau

2. Calders

3. Batholith

4. Volcanic neck

5. Sills and dikes

6. Dome mountains

 

Term

Lava Plateau

Definition

Thin lava erupts from long cracks, flooods and hardens in a plain. 

Over time builds up into a plateau

Term
Caldera
Definition

Massive eruptions empties the vent and magma chamber leaving the volcano hollow.  Without internal support, top of the volcano collapses inward.

Term
Batholith
Definition
a magma chamber that has  cooled into solid rock
Term
Volcanic neck
Definition

the surrounding volcanic  cone is eroded away leaving magma that had hardened in the volcanic pipe

Term
Sills and dikes
Definition

Magma forces itself among rock layers and hardens.  Sills are in between two rock layers.  Dikes cut across several rock layers.

Term
Dome mountains
Definition

smaller bodies of magma (called laccoliths) cause the earth's surface to buldge upward

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