Download Chapter 10 Notes: Volcanoes and Other Igneous Activity Name: The

Chapter 10 Notes: Volcanoes and Other Igneous Activity
Name:
1. The Nature of Volcanic Eruptions
a. Factors Affecting Eruptions
i. Factors that determine the violence of an eruption
1. ______________ of the magma
2. ______________ of the magma
3. ____________________________ in the magma
ii. Viscosity
1. Viscosity is the measure of a material’s ______________ to flow
2. Factors affecting viscosity
a. ______________ (hotter magmas are less viscous)
b. ______________ (silica content)
i. High silica – High viscosity (e.g. rhyolitic lava)
ii. Low silica – more fluid (e.g. basaltic lava)
iii. Dissolved Gases
1. Mainly ____________________________ and carbon dioxide
2. Gases expand near the surface
3. A ______________ is an opening in the surface of Earth through which molten rock
and gases are released
4. Provide the force to extrude lava
5. Violence of an eruoption is related to ____________________________ gases
escape from magma
a. Gases escape ______________ from fluid magma
b. ______________ magma produces a _____________________ eruption.
b. Volcanic Material
i. Lava Flows
1. ______________ lavas are more fluid.
2. Types of lava
a. ______________ lava – resembles braids in ropes
b. ______________ lava – rough, jagged blocks
ii. Gases
1. 1-5% of magma by ______________
2. Mainly water vapor and carbon dioxide
iii. Pyroclastic Materials
1. Pyroclastic materials is the name given to particles ______________ in volcanic
eruptions.
2. The fragements ejected during eruptions range in size from __________________
and ____________________________ (less than 2 millimeters) to pieces that
weigh several tons.
3. Types of pyroclastic material
a. ______________ – fine, glassy fragments
b. Pumice – frothy, air-filled lava
c. ______________ – walnut-sized particles
d. Cinders – pea-sized particles
4. Particles larger than lapilli
a. ______________ - hardened lava
b. ______________ - ejected as hot lava
c. Types of Volcanoes
i. The three main volcano types are ______________ volcanoes, ______________________,
and ______________ cones.
ii. Anatomy of a volcano
1. A volcano is a ______________ formed of lava and/or pyroclastic material.
2. A ______________ is the depression at the ______________ of a volcano or that
which is produced by a meteorite impact.
3. A ______________, or pipe, carries gas-rich magma to the surface.
iii. Shield Volcanoes
1. Are broad, gently sloping volcanoes built from ____________________________.
iv. Cinder Cones
1. Small volcanoes built primarily of pyroclastic material ejected from ___________
______________.
a. ______________ slope angle
b. Rather small in size
c. Frequently occur ____________________________
v. Composite Cones
1. Volcanoes composed of both ____________________________ and ___________
______________.
a. Most are adjacent to the __________________________ (e.g. Mt. Rainier).
b. ______________ size
c. Interbedded lavas and pyroclastics
d. ______________ type of activity
a. Other Volcanic Landforms
a. Calderas
i. Calderas are ____________________________ in volcanoes
ii. Nearly circular
iii. Formed by ______________
iv. Size exceeds ______________ in diameter
b. Lava Plateaus
i. Fluid basaltic lava extruded from crustal fractures called ______________
2. Intrusive Igneous Activity
a. Plutons
i. Plutons are intrusive igneous structures that result from the ______________ and
______________ of ______________ beneath the surface
1. Intrusive igneous bodies, or plutons, are generally classified according to their:
a. ______________
b. ______________, and
c. ______________ to the surrounding rock layers
ii. Sills and Laccoliths
1. Sills and laccoliths are pluton that form when magma is intruded ______________
to the surface
2. ______________ resemble buried lava flows and may exhibit _________________
3. ______________ are ______________ masses that arch overlying strata upward
iii. Dikes
1. Dikes are ____________________________ intrusive igneous features that cut
across preexisting rock layers.
2. Many dikes form when magma from a large magma chamber invades fractures in
the surrounding rocks
iv. Batholiths
1. Batholiths are large masses of igneous rock that formed when magma intruded at
depth, became crystallized, and subsequently was exposed by erosion.
2. An intrusive igneous body must have a surface exposure ____________________
to be considered a batholith
a. Origin of Magma
i.
Geologists conclude that magma originates when essentially solid rock, located in the
______________ and ____________________________, partially melts.
ii.
The most obvious way to generate magma from solid rock is to ______________ the
temperature above the level at which the rock begins to melt.
iii.
The ____________________________ - Earth’s natural temperature increases with depth
but is not sufficient to melt rock in the ______________ and ______________
iv.
Additional heat is generated by
i. ______________ in subduction zones
ii. Crustal rocks heated during ______________
iii. ______________, ______________ mantle rocks
v.
Role of Water
i. Causes rock to melt at a ______________ temperature
ii. Plays an important role in ______________ ocean plates
3. Plate Tectonics and Igneous Activity
a. Convergent Plate Boundaries
i. The basic connections between ______________ and ______________ is that plate
motions provide the mechanisms by which mantle rocks melt to generate magma.
ii. Ocean-Ocean
1. Rising magma can form ____________________________ in an ocean (Aleutian
Islands).
iii. Ocean-Continent
1. Rising magma can form ______________ volcanic arcs (Andes Mountains).
b. Divergent Plate Boundaries
i. The greatest volume of volcanic rock is produced along the ___________________ system
1. ______________ pulls apart
2. Less ______________ on underlying rocks
3. Partial ______________ occurs
4. Large quantities of ____________________________ are produced
c. Intraplate Igneous Activity
i. ______________ ______________ is igneous activity that occurs within a
____________________________ away from plate boundaries
1. Most intraplate volcanism occurs where a mass of hotter-than-normal mantle
material called ____________________________ rises toward the surface
2. The activity forms localized volcanic regions called __________________.
3. Examples include the Hawaiian Islands and the Columbia Plateau.