Exam 2; Practice Flashcards
Molten rock material, which is the parent substance of all igneous rock is called
a. mantle
b. magma
c. ophiolite
d. meltamite
b. magma
In _________, melting occurs because of a decrease in pressure without decreasing temperature
a. decompression melting
b. flux melting
c. heat transfer
d. volatile melting
a. decompression melting
What role does water play in generating magma?
a. water lowers the density of the rock, allowing it to melt.
b. water cools the rock, preventing melting
c. water lowers the melting temperature of the rock allowing it to melt
d. this is a trick question, water has no effect on the generation of magma
c. water lowers the melting temperature of the rock allowing it to melt
Which list shows magmas in order of INCREASING silica content?
a. Intermediate/Andestic, Mafic/Basaltic, Felsic/Rhyolitic
b. Felsic/Rhyolitic, Intermediate/Andesitic, Mafic/Basaltic
c. Mafic/Basaltic, Intermediate/Andesitic, Felsic/Rhyolitic
d. this is a trick question, all magmas have the same silica content.
c. Mafic/Basaltic, Intermediate/Andesitic, Felsic/Rhyolitic
Which of the following statements is false?
a. Temperature and composition affect the viscosity of magmas
b. hotter magmas are less viscous
c. higher silica content magmas are less viscous
d. lower silica content magmas are less viscous
c. higher silica content magmas are less viscous
A rock with an aphanitic texture indicates that the parent magma
a. cooled slowly
b. cooled rapidly
c. experienced two periods of cooling, first slow then fast
d. was generated at a divergent plate margin
b. cooled rapidly
Granite and rhyodite typically have the same
a. cooling history
b. chemical composition
c. texture
d. all of the above
b. chemical composition
What was the rate of cooling and the environment of formation for an intrusive igneous rock?
a. slow because the magma was insulated below the surface
b. fast because it was erupted from a volcano
c. slow because it cooled in a volcanic lava flow far from the vent
d. fast because it cooled size miles below the Earth’s surface
a. slow because the magma was insulated below the surface.
Magmas evolve as the result of several different processes. Which process of magma evolution is detected in Figure 6.
a. crystal setting
b. assimilation
c. magma mixing
d. filter pressing
c. magma mixing
Which type of intrusive igneous body is depicted in figure 7?
a. dike
b. Sill
d. laccolith
d. batholith
a. dike
In order to cover such large expanses of seafloor, shield volcanoes erupt _____ lava.
a. rhyolitic
b. andesitic
c. basaltic
d. felsic
c. basaltic
Which type of volcano is depicted in figure 12?
a. shield volcano
b. stratovolcano
c. cinter cone
d. continental caldera
b. stratovolcano
Most of the Earth’s explosive volcanoes are located in a zone that encircles the Pacific Ocean called the Ring of Fire. The types of volcanoes that commonly form in this zone are called ______ which form by the melting of rocks during _____.
a. cinder cones, subduction
b. stratovolcanoes, subduction
d. shield volcanoes, subduction
d. stratovolcanoes, rifting
b. stratovolcanoes, subdution
What is a pyroclastic flow?
a. a fast-moving avalanche of hot rock, ash, and gas
b. a slurry-like flow of hot ash, mud and water
c. an avalanche of ash and water
d. a flow of volcanic rock pieces and molten lava
a. a fast-moving avalanche of hot rock, ash, and gas
What is a lahar?
a. a volcanic mudflow
b. a particularly deadly type of volcano
c. a volcanic ash cloud
d. a type of respiratory failure associated with ash accumulation in the lungs
a. a volcanic mudflow
________ weathering involves breaking apart rocks and crystals into smaller pieces of the same material that is being weathered (no change in composition)
a. physical/mechanical
b. Hydrolysis
c. dissolution
d. chemical
a. physical/mechanical
What type of weathering is depicted in Figure 16?
a. salt crystal growth
b. impacts/abrasion
c. freeze-thaw action (frost wedging)
d. pressure relief
c. freeze-thaw action (frost wedging)