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