ch 18- volcanic activity
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Bellwork Ch 18-Volcanic Activity Compare/Contrast- Types of Volcanoes Directions- Open your binder to the bellwork section and complete the table. (Textbook p480). Ch 18- Volcanic Activity. Take out your notes. As we go over chapter 18, add missing details to your notes (main idea). Volcano. - PowerPoint PPT PresentationTRANSCRIPT
BellworkCh 18-Volcanic Activity
Compare/Contrast- Types of VolcanoesDirections- Open your binder to the bellwork section
and complete the table. (Textbook p480)Shield Cinder-
ConeComposite
Drawing
Shape Wide, kind of flat
Steep sides, small volcano
Large, wider
Type of Eruptions
quiet More explosive than shield
violent
Low/HighGas content
low Higher than shield
High
Low/High Silica content
low More silica & water than shield
High silica, water
Low/HighViscosity
low Higher than shield
Very high
Ch 18- Volcanic ActivityTake out your notes. As we go over chapter 18, add missing details to
your notes (main idea)
VolcanoA naturally occurring opening in the
surface of the Earth through which molten, gaseous, and solid material is ejected
MAGMAMixture of molten rockSuspended by mineral grainsDissolved gasForms:
High temperaturesPressureWaterSource material
TYPES OF MAGMA
Basaltic
Basalt igneous rock
Ex: Hawaiian Islands
Andesitic
Andesite igneous rock
Ex: Mt. Saint Helens / Tambora
Rhyolitic
Granite igneous rock
Ex: Yellowstone Nat’l Park
What is viscosity?Property of
fluid that resists flowing
The hotter the magma or lava, the lower the viscosity.
MAGMA COMPOSITION & CHARACTERISTICS
HOW MAGMA AFFECTS THE CRUSTBLOCKS TO BREAK OFF AND SINK
MELTS OTHER ROCKSROCKS TO FRACTURE
PLUTONS When magma cools, minerals form. Over a very long period of time,
these minerals will combine to form intrusive igneous rock bodies called plutons.
Largest plutons are called batholiths. Common in the interiors of major mountain chains. – primarily granite
Irregular shaped plutons are called stocks.
Mushroom-shaped pluton is called a laccoliths.
Sills – pluton intrudes parallel to layer rocks.
Dikes cuts across preexisting rocks.Coast Range Batholith in British Columbia
PLUTONS
Parts of a Volcano
VENT- the vent is the opening from which lava flows. Dust, ash, and rock particles can also be thrown out of the vent!
Crater- the top of the volcano. It is a funnel shaped pit. It is formed when the material explodes out of the vent!
Volcanic cone-is the pile oflava, dust, ashes,and rock aroundthe vent. It canbe found in different shapes!
3 Types of Volcanoes
Shield Cinder Cone Composite
They are classified by how they form.
Shield Volcano Is wide and
somewhat flat. It forms from a
quiet eruption. Lava flows out
quietly and for great distances.
Cinder Cone Volcano Has tall, very
steep sides. Has explosive
eruptions. This eruption
produces a lot of cinder and ash.
Composite Volcano Form from
explosive eruptions.
Produce a lot of lava and ash.
Is small, with steep sides.
Tephra Rock fragments, classified by size,
that are thrown into the air during a volcanic eruption and fall to the ground.
Pyroclastic flow Swift-moving, potentially deadly
clouds of gas, ash, and other volcanic material produced by a violent eruption.
Hot Spot
Unusually hot area in Earth’s mantle that is stationary for long periods of time, where high-temperature plumes of mantle material rise toward the surface.
Where do volcanoes occur?
Active volcanoes generally occur close to the major tectonic plate boundaries. Along convergent and divergent plate boundaries.
They also form over hot spots – hot areas in the mantle
Volcanoes can remain inactive, or dormant, for hundreds or thousands of years before erupting again. During this time they can become covered by vegetation making them difficult to identify. Once a volcano has been dormant for more than 10,000 years, it is termed extinct.
Test- Plate Tectonics/Volcanoes
Next Class!! Frida
* Be sure to study from the study guides, notes, bell work, class work and homework.
Classwork/AssignmentTextbook/Review for exam
1. Problem-Solving Lab- Textbook page 486 Analysis Qs 1,2/ Think Critically Qs 3,4
2. Page 447 Compare/Contrast #63. Page 454 Concept Mapping # 64. Page 459 Making Tables # 65. Page 475 Concept Mapping # 7You may work with a partner- All work is
due in basket at the end of class!!!