Geology Test 2 (online quizzes) – Flashcards
80 test answers
Unlock all answers in this set
Unlock answers 80question
What composition is 90% of the lava erupted on Earth?
answer
Basaltic
Unlock the answer
question
What type of lava flow means "on which one can walk" and resembles twisted braids of ropes?
answer
Pahoehoe flows
Unlock the answer
question
What feature forms when a lava flow forms underwater along the mid-oceanic ridge?
answer
Pillow lava
Unlock the answer
question
What is the most abundant gas expelled during a volcanic eruption?
answer
Water vapor
Unlock the answer
question
What is a fumarole?
answer
A small vent that emits only gases from a volcano
Unlock the answer
question
How many total shield volcanoes are found on the Big Island of Hawaii?
answer
Five
Unlock the answer
question
What material comprises cinder cone volcanoes, which have a high angle of repose?
answer
Loose pyroclastic material
Unlock the answer
question
Which of the following volcanic hazards can occur when a volcano is not erupting?
answer
Lahar
Unlock the answer
question
What destroyed the city of Pompeii and when?
answer
in 79 ad; eruption of Mount Vesuvius
Unlock the answer
question
What is the smallest of the three volcano types?
answer
Cinder Cone
Unlock the answer
question
Which type of caldera forms from the collapse of a volcano caused by subterranean drainage from a central magma chamber?
answer
Hawaiian-type caldera
Unlock the answer
question
What type of lava occurs in lava domes that form when lavas squeeze out of a vent, producing a dome-shaped mass?
answer
Felsic
Unlock the answer
question
What type of plate boundary produces continental volcanic arcs?
answer
Ocean-to-continent convergent plate boundaries
Unlock the answer
question
What type of volcanism supposedly produced both Hawaii and Yellowstone?
answer
Intraplate (hot spot)
Unlock the answer
question
Which volcanic hazard poses the greatest threat to human life?
answer
Pyroclastic flows
Unlock the answer
question
How many people live in the vicinity of an active volcano?
answer
500 million
Unlock the answer
question
What is the difference between magma and lava?
answer
Magma is molten rock inside Earth, and lava is molten rock at Earth's surface.
Unlock the answer
question
What is the "melt" of a magma composed of?
answer
Mobile silicon, oxygen, aluminum, potassium, calcium, sodium, iron, and magnesium ions
Unlock the answer
question
Do extrusive igneous rocks tend to be fine-grained or coarse-grained?
answer
Fine-grained, because they form when molten rock cools quickly at the surface
Unlock the answer
question
Which of the following is richer in silica?
answer
Nonferromagnesian (light) silicates
Unlock the answer
question
What type of igneous rock is peridotite?
answer
Ultramafic
Unlock the answer
question
Viscosity refers to a fluid's resistance to flow. The more viscous the magma, the "thicker" it is. How does silica content affect a magma's viscosity?
answer
The greater the silica content, the more viscous the magma.
Unlock the answer
question
What does a phaneritic texture indicate?
answer
A slow rate of cooling
Unlock the answer
question
What is the name of large crystals in an igneous rock with a porphyritic texture?
answer
Phenocrysts
Unlock the answer
question
Which igneous rock has a glassy texture?
answer
Obsidian
Unlock the answer
question
What two basic characteristics are used to classify igneous rocks?
answer
Texture and mineral composition
Unlock the answer
question
What mineral gives some granites a pinkish color?
answer
Potassium feldspar
Unlock the answer
question
What igneous rock floats on water and resembles a gray, frothy mass of intertwined glass shards?
answer
Pumice
Unlock the answer
question
What is diorite?
answer
A phaneritic igneous rock with the same composition as andesite
Unlock the answer
question
What effect does the addition of volatiles such as water have on a descending slab of oceanic lithosphere at a subduction zone?
answer
Lowers the melting temperature
Unlock the answer
question
What is the average geothermal gradient in the upper crust?
answer
25 degrees Celsius per kilometer depth
Unlock the answer
question
What does Bowen's reaction series illustrate?
answer
Minerals crystallize from a cooling magma in a systematic fashion.
Unlock the answer
question
What name refers to the formation of one or more secondary magmas from a single parent magma?
answer
Magmatic differentiation
Unlock the answer
question
What igneous intrusion is forcibly injected between sedimentary strata, causing the beds above to arch?
answer
Laccolith
Unlock the answer
question
Of the descriptions given, which rock type and environment has the highest concentration of rare elements?
answer
Pegmatite; crystallized from a water-rich, highly differentiated residual magma
Unlock the answer
question
Which of the following statements about diamonds is true?
answer
Diamonds are transported from the mantle to the surface via kimberlite pipes.
Unlock the answer
question
Which type of sedimentary rock forms when ions in a solution are precipitated through inorganic or biological processes?
answer
chemical sedimentary rock
Unlock the answer
question
Which of the following is a collective term for all of the chemical, physical, and biological changes that take place after sediments are deposited and during and after lithification?
answer
diagenesis
Unlock the answer
question
What are the primary constituents of detrital sedimentary rocks?
answer
quartz and clay minerals
Unlock the answer
question
What is the primary basis for classifying detrital sedimentary rocks?
answer
particle size
Unlock the answer
question
Which of the following detrital sedimentary rocks is likely to be well sorted?
answer
quartz sandstone from ancient dunes
Unlock the answer
question
Which of the following sedimentary rocks is associated with deposition in an oxygen-poor swamp environment?
answer
black shale
Unlock the answer
question
Which of the following chemical sedimentary rocks is soft, porous, and made almost entirely of the hard parts of microscopic calcareous marine organisms?
answer
chalk
Unlock the answer
question
When a body of seawater evaporates, the minerals precipitate in sequence of their solubility. What is the correct sequence of mineral precipitation from least soluble (first) to most soluble (last)?
answer
gypsum, halite, sylvite
Unlock the answer
question
Which is the highest-grade coal with the greatest concentration of carbon?
answer
anthracite
Unlock the answer
question
What two processes occur during lithification of unconsolidated sediment into solid rock?
answer
compaction and cementation
Unlock the answer
question
How might an iron oxide cement be identified on a sedimentary rock?
answer
Rock will have an orange, dark red, or rust-colored appearance.
Unlock the answer
question
What type of texture do all detrital sedimentary rocks have?
answer
Clastic
Unlock the answer
question
Which sedimentary environment category would most glacial deposits belong to?
answer
continental
Unlock the answer
question
Which of the following sedimentary structures can be used to determine the direction of ancient wind or water currents?
answer
ripple marks
Unlock the answer
question
Graphite is a nonmetallic mineral resource. What was formerly a common use for graphite?
answer
pencil lead
Unlock the answer
question
Which of the following is not a resource derived from sedimentary rocks?
answer
marble building stones
Unlock the answer
question
Coal is formed mostly from a(n) ____ environment, whereas oil and natural gas form from a(n) ____ environment.
answer
swamp; oxygen-poor marine
Unlock the answer
question
What percentage of the energy consumed in the United States today comes from fossil fuels?
answer
82 percent
Unlock the answer
question
Which of the following is a way in which carbon is removed from the atmosphere?
answer
plant photosynthesis
Unlock the answer
question
What type of sedimentary rock is dolostone?
answer
Chemical sedimentary rock
Unlock the answer
question
Which of the following happens to a rock during metamorphism?
answer
It remains essentially solid.
Unlock the answer
question
To what does the term parent rock of a metamorphic rock refer?
answer
the preexisting sedimentary, igneous, or metamorphic rock that underwent metamorphism
Unlock the answer
question
What is the ultimate goal of a rock as it gradually changes in response to a new set of environmental conditions?
answer
to reach equilibrium with the new environment
Unlock the answer
question
Which of the following is not an agent of metamorphism?
answer
magnetism
Unlock the answer
question
At what depth and temperature do clay minerals tend to become unstable and begin to recrystallize?
answer
8 km; 200° C
Unlock the answer
question
What is differential stress?
answer
stress placed on a rock by unequal forces, which squeeze a rock greater in one direction than in others
Unlock the answer
question
Which of the following is a foliated metamorphic rock?
answer
schist
Unlock the answer
question
In what direction, relative to the direction of differential stress, do foliations typically form?
answer
perpendicular
Unlock the answer
question
What is the accessory mineral in a staurolite mica-schist?
answer
staurolite
Unlock the answer
question
How can a student tell slate and phyllite apart?
answer
Phyllite has a glossy sheen and a somewhat wavy surface, whereas slate is fine-grained and breaks into flat slabs.
Unlock the answer
question
Which type of metamorphism occurs when a meteorite strikes the Earth surface at high speed?
answer
impact metamorphism
Unlock the answer
question
Where does most hydrothermal metamorphism occur?
answer
mid-ocean ridge systems
Unlock the answer
question
What is burial metamorphism?
answer
metamorphism that occurs when massive amounts of sedimentary or igneous material accumulates in a subsiding basin
Unlock the answer
question
Can metamorphic rocks contain fossils?
answer
Yes, when a sedimentary parent rock undergoes low-grade metamorphism, some of the fossils can persist.
Unlock the answer
question
What happens to grain size as metamorphic intensity increases?
answer
It increases.
Unlock the answer
question
Which index mineral indicates extremely high-grade metamorphism?
answer
sillimanite
Unlock the answer
question
What are migmatites?
answer
rocks transitional between igneous and metamorphic
Unlock the answer
question
What is the parent rock for gneiss?
answer
granite or shale
Unlock the answer
question
What rock forms along fault zones and is composed of broken and crushed rock fragments?
answer
fault breccia
Unlock the answer
question
Which of the following types of metamorphism is related to differential stress?
answer
regional metamorphism
Unlock the answer
