Geology HW Questions
What is the process that is thought to generate most granitic magmas?
A basaltic pond of magma becomes trapped below continental crust and partially melts this silica-rich crust into a granitic magma.
What causes the volcanoes and deep valleys of East Africa?
A continental rift along parts of the African continent beginning to slowly separate
What type of boundary occurs along the Aleutian Islands in the North Pacific?
A convergent boundary occurs on a volcanic arc above the northward-subducting Pacific plate
Science uses observations of phenomena in order to make interpretations. Which of the following is an observation?
A fold is visible in an outcrop.
Which of the following statements applies to the asthenosphere, but not the lithosphere?
A zone in the upper mantle that deforms by plastic flowage
Which type of basaltic lava flow has its surface covered with sharp-edged, angular blocks and rubble?
A'a
Which of the following is a feature of an aa flow?
Aa flows have sharp, jagged edges.
Which scientist argued forcefully for continental drift in the early part of the 20th century?
Alfred Wegener
Which of the following is consistent with the plate tectonic theory?
As a plate subducts into the asthenosphere, it pulls the trailing plate along.
What volcanic events formed Crater Lake, Oregon? When did they take place?
Caldera collapse followed by major ash and pyroclastic-flow eruptions; 7000 years ago.
What causes mountain formation in a continental rifting setting?
Lithospheric blocks, bounded by normal faults, tilt and rise.
Why would a plume of solid silicate rock rising slowly from deep in the mantle begin melting as it neared the base of the lithosphere?
Melting temperatures drop because the pressure is lowered.
Which of the following features would you find in an ocean basin? CHOOSE ALL THAT APPLY.
Mid-Atlantic Ridge, Peru-Chile Trench
Which of the following paleoclimatic evidence supports the idea of the late Paleozoic supercontinent in the Southern Hemisphere?
Tillites (rocks formed by glaciers) in South Africa and South America
Compared to the age of Earth accepted as correct today, how did 17th- and 18th-century proponents of catastrophism envision Earth's age?
They believed Earth to be much younger than current estimates.
To what is the geologically recent volcanic activity in Yellowstone National Park usually attributed?
Yellowstone volcanism is usually attributed to intraplate, hot spot volcanism.
______ is a feature that results from processes associated with an oceanic-oceanic convergent plate boundary. CHOOSE ALL THAT APPLY.
a deep ocean trench
A transform plate boundary is characterized by _____.
a deep, vertical fault along which two plates slide past one another in opposite directions
What type of plate boundary is usually associated with pull-apart rift zones?
a divergent plate boundary
______ is a feature of a divergent plate boundary. CHOOSE ALL THAT APPLY.
a rift valley, an oceanic ridge
Which of the following is a basic structural component of the most common mineral group?
a silicon-oxygen tetrahedron
Where are active mountain belts most likely to be found?
along the margins of continents
Of the following choices, which best describes Mt. St. Helens?
an explosive stratovolcano
Which of the following pairs of igneous rocks exhibit aphanitic texture?
andesite; rhyolite
What type of magma typically comprises stratovolcanoes?
andesitic
Which term describes the changing of the composition of magma by incorporating surrounding host rock?
assimilation
How can a magma body change its composition? CHOOSE ALL THAT APPLY.
assimilation magmatic differentiation magma mixing crystal settling
What is the dominant lava erupted from volcanoes on Hawaii and Iceland?
basalt
What type of magma is the most abundant at oceanic-spreading centers?
basaltic
What type of volcanoes are Kilauea and Mauna Loa in Hawaii?
basaltic shield volcanoes
What is the name of dark-colored mica?
biotite
Which carbonate mineral reacts readily with cool, dilute hydrochloric acid (HCl) to produce visible bubbles of carbon dioxide gas?
calcite
Which nonsilicate mineral has carbonate as a negatively charged complex ion?
calcite
Fold-and-thrust belts are the result of ________ stress whereas fault block mountains are the result of ________ stress.
compressional; tensional
Which term describes a relatively stable interior portion of a continent?
crayon
The _____ is the thinnest layer of Earth.
crust
Volcanic island arcs are found near which features on the seafloor?
deep-ocean trenches
What mineral is the hardest known substance in nature?
diamond
Which of the following rocks has the same mineral composition as andesite?
diorite
The last minerals to crystallize on Bowen's Reaction Series result in igneous rocks with a _____ composition.
felsic
Which of the following is considered a ferromagnesian silicate? CHOOSE ALL THAT APPLY.
garnet, biotite
Which of the following minerals is a silicate?
muscovite
Which of the following minerals is in the mineral group known as mica?
muscovite
Which of the following minerals crystallize early in Bowen's Reaction Series?
olivine
What type of igneous rock consists of very coarse crystals?
pegmatite
What ultramafic rock is thought to be common in Earth's mantle but rare in the crust?
peridotite
Which of the following rocks is composed mainly of ferromagnesian minerals?
peridotite
An igneous rock with a ______ texture solidified deep within Earth.
phaneritic
Which term describes a texture of igneous rocks that crystallized over a single, long period?
phaneritic
which texture listed below would be most unlikely to occur in an extrusive igneous rock?
phaneritic
Which of the following is a characteristic of an igneous rock found in a batholith?
phaneritic texture
Where in Earth is the asthenosphere?
in the mantle under the lithosphere
Which list below identifies the layers of the Earth in the correct order from the center?
inner core, outer core, mantle, crust
What is the name given to an atom that gains or loses electrons in a chemical reaction?
ion
What is the dominant feldspar in basalt?
plagioclase
The most abundant minerals found in granitic (felsic) igneous rocks include ______. CHOOSE ALL THAT APPLY.
potassium feldspar, quartz
Which volcanic rock is extremely vesicular and glassy?
pumice
Which of these minerals would be the first to crystallize in a body of magma?
pyroxene
What mineral is composed of silicon dioxide (SiO2)?
quartz
Which of the following is an aphanitic igneous rock?
rhyolite
Which one of the following shows the correct order from left to right of decreasing magmatic viscosity?
rhyolite, andesite, basalt
Which of the following describes the way light reflects from the surface of a mineral?
luster
What is the source of magma for most intraplate volcanism?
mantle plumes
In a porphyritic volcanic rock, which mineral grains are the last to crystallize?
matrix or groundmass
Which of the following were used by Wegener to support the continental drift hypothesis? CHOOSE ALL THAT APPLY.
mesosaurus fossils found on South America and Africa, matching geologic units in the Appalachian and Caledonian Mountains, major coal fields found in the eastern United States
What are the most prominent features on the ocean floor?
mid-oceanic ridges
Which of the following is NOT a fundamental particle found in atoms?
selectron
The flat stable interior of a continent within a craton is called a ____.
shield
Which volcanoes are sometimes very large, with a gently sloping mound composed mainly of lava flows?
shield
Which kind of volcanism is typical of mid-oceanic ridge systems?
submarine; basaltic lava flows
What term describes the sizes, shapes, and arrangements of mineral grains in an igneous rock?
texture
Which of the below is an example of a feature associated with an oceanic-continental convergent plate boundary?
the Cascade Mountain Range
Which region has the greatest concentration of current active volcanoes?
the circum-Pacific area or "Ring of Fire"
A mineral's streak is _________.
the color of the mineral in powdered form
The largest layer (by volume) of Earth, ____, is composed primarily of _____.
the mantle; peridotite
Which of the following is NOT one of the possible steps of a scientific investigation?
the publication of conclusions without prior experimentation or observation
What is luster?
the quality of light reflected from a mineral's surface
Which layer forms the relatively cool, brittle plates of Earth's crust?
the top of the lithosphere
What is the most common volatile constituent in both magmas and volcanic gases?
water
Sedimentary rocks are formed from igneous rocks beginning with the process of _____.
weathering
_____ is the process by which rocks breakdown in place to produce soils.
weathering
Which of the following igneous rocks has a pyroclastic texture, meaning it was formed from a glowing avalanche?
welded tuff
Which of the following best describes the fundamental concept of superposition?
Any sedimentary deposit accumulates on top of older rock or sediment layers
What is the currently accepted age of Earth?
4.6 billion years
How is this chain of volcanic islands forming?
A tectonic plate is moving over a mantle plume, which burns through the plate to create a chain of volcanoes.
What type of region is the modern-day Red Sea?
A rift zone that may eventually open into a major ocean if Arabia and Africa continue to separate
Which of the following statements about the rock cycle is correct?
A sedimentary rock subjected to intense heat and pressure will become a metamorphic rock.
What is an ion?
An atom that has more or fewer electrons than it should
How do volcanic bombs originate?
As erupted magma blobs that partly congeal before falling to the ground
Where in the ocean does oceanic lithosphere sink into the mantle?
At subduction zones along convergent plate boundaries
What type of lava is produced at a divergent plate boundary?
Basaltic
Why was Wegener's continental drift hypothesis rejected?
Because Wegener could not identify a mechanism capable of moving continents
Why are lava flows typically finer-grained than intrusive igneous rocks?
Because the extrusive magma cools quickly and mineral grains do not have time to grow
Which one of the following statements concerning cinder cones is false?
Cinders and other pyroclastic particles can be consolidated into welded tuff.
Along which tectonic boundary will chains of composite cone volcanoes be located?
Convergent boundary
Which layer of the Earth is the thinnest?
Crust
Which of the following materials or features are not found at mid-ocean ridges?
Deep submarine trenches
Which one of the following is an important fundamental assumption underlying the plate tectonic theory?
Earth's diameter has been essentially constant over time
What is the difference between extrusive igneous rocks and intrusive igneous rocks?
Extrusive igneous rocks cool and solidify on the Earth's surface, whereas intrusive igneous rocks cool and solidify beneath the Earth's surface.
Concordant plutons cut across existing structures while discordant plutons are parallel to existing features.
False
There can be no variation of mineral composition in order for the substance to remain the same mineral.
False
What is the term used to describe increased temperature with depth in the Earth?
Geothermal gradient
Which of the following is a mineral?
Ice
Which of the following best defines a mineral and a rock?
In a mineral, the constituent atoms are bonded in a regular, repetitive, internal structure; a rock is a lithified or consolidated aggregate of different mineral grains.
Which of the following was never proposed as evidence supporting the existence of Pangaea?
Islands along the Mid-Atlantic Ridge with rocks dating back from 542 million to 2500 million years ago
Which 18th-century English geologist proposed uniformitarianism?
James Hutton
In which layer of the Earth does the convection necessary for plate motion occur?
Mantle
In 1980, _____ was the first Cascade Range volcano to erupt since Mt. Lassen, California, in 1915-16.
Mt. St. Helens
What causes the linear patterns associated with paleomagnetism on either side of mid-oceanic ridges?
Normal and reversed magnetized strips roughly parallel to the ridge
Where are the majority of transform faults located?
On the ocean floor offsetting segments of oceanic ridge
The ring of fire is a narrow zone of composite cone volcanoes rimming the ________ Ocean.
Pacific
Which ocean basin is rimmed by the most subduction zones?
Pacific
Which type of basaltic lava flow has a fairly smooth, unfragmented, ropy surface?
Pahoehoe
The former, late Paleozoic supercontinent is known as _____.
Pangaea
What are the basic differences between the disciplines of physical and historical geology?
Physical geology includes the study of how rocks form and of how erosion shapes the land surface; historical geology involves the study of rock strata, fossils, and geologic events, utilizing the geologic time scale as a reference.
What is the definition of orogenesis?
Processes that collectively form a mountain belt
________ is pulverized rock, lava fragments, and ash erupted from a volcano.
Pyroclastic material
Which one of the following statements is not correct?
Sedimentary rocks may weather to form igneous rocks.
Which of the following is NOT evidence supporting the theory of plate tectonics?
Shifting plates were caused by changes in the Moon's orbit
Which of the following pairs of elements are the most abundant in the continental crust?
Silicon and oxygen
What process is evident at oceanic trenches?
Sinking of oceanic lithosphere into the mantle at a subduction zone
Which of the following statements best describes the Hawaiian volcanoes?
The Hawaiian volcanoes are situated in the interior of a Pacific plate above a hot spot deep in the mantle.
Which of the following is correct for isotopes of the same element?
The atoms have different numbers of neutrons and the same number of protons.
Why must geologists understand the magnitude of geologic time?
The magnitude of geologic time spans billions of years and thus differs greatly from the magnitude of time people deal with on an everyday basis (e.g., hours, weeks).
What evidence did the Deep Sea Drilling Project find about the dates of rocks in the ocean basins?
The ocean basins are relatively young; most ocean basin rocks and sediments are Cretaceous or younger in age.
What is the definition of lithification?
The process by which sediments are made into rock
Which statement about the theory of plate tectonics is correct?
The rigid lithosphere plates overlay the hotter and weaker asthenosphere.
Which of the following pieces of evidence supports the plate tectonic theory?
The stripe patterns of high- and low-intensity magnetism are the same on both sides of an oceanic ridge.
Which one of the following best describes volcanism of the Cascade Range in the northwestern United States?
The volcanism is related to plate subduction.
Which of the following best characterizes ferromagnesian silicates?
They are black to dark-green silicate minerals that contain iron and magnesium
Which of the following properly describes Mount St. Helens and the other Cascade volcanoes?
They are young, active volcanoes built on a continental margin above a sinking slab of oceanic lithosphere.
Which two scientists proved that a symmetrical magnetic pattern existed in seafloor basalts and related those stripes to spreading at a mid-oceanic ridge?
Vine and Matthews
________ is a material's resistance to flowing.
Viscosity
What kind of volcanic chain is present in this image?
Volcanic island arc
Which feature of Wegener's idea of continental drift contributed to its rejection by the scientific community?
Wegener proposed that gravitational forces from the Sun and Moon could move continents.
What popular doctrine in the 17th and early 18th centuries proposed that Earth was created through a series of profound worldwide disasters?
catastrophism
Which one of the following mineral groups exhibits a sheet-like silicate structure?
clay minerals
What is the tendency of certain minerals to break along smooth, parallel planes called?
cleavage
What two processes occur during lithification of sedimentary rocks?
compaction and cementation
What do pumice and obsidian have in common?
glassy texture
Which rock would be most likely to contain visible quartz and potassium feldspar crystals?
granite
A very long-lived magma source located deep in the mantle is called a(n) _____.
hot spot
A(n) ___ is a tentative explanation, whereas a(n) ____ has survived extensive scrutiny over many years.
hypothesis; theory
What type of rocks form by crystallization and consolidation of molten magma?
igneous
What type of rock results from the crystallization of molten rock?
igneous rock
Which two elements are found in all silicate minerals?
silicon and oxygen
A _____ is a well-tested and widely accepted view that best explains certain scientific observations.
theory
What geological theory is often paraphrased as "the present is the key to the past"?
uniformitarianism
A _____ is an open cavity in a volcanic rock that was filled by a gas bubble when the lava was still mainly liquid.
vesicle
What is the name of the small holes created by gas bubbles on the surface of scoria?
vesicles
Which of the following can be a product of a composite volcano eruption? CHOOSE ALL THAT APPLY.
volcanic bombs gases cinders ash andesitic lava