Geology Final Exam

Mineral Definition: A natural occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties. Based on the definition, which of the following substances are considered a mineral?

* a natural quartz crystal made into a crystal ball
* a natural diamond from a jewelry store
* an amazonite crystal given away in class

Carbon has an atomic number of 6 and a number of isotopes (C12, C13, C14). Which statement below is **INCORRECT** abut carbon element?

carbon isotopes have a difference number of protons

The Earth’s oceanic crust is made up primarily of _

basalt

The structure of atoms is mainly made of the inner nucleus with protons and neutrons, and the outer orbiting electrons. An element is defined by the number of protons, by can have various numbers of neutrons. When an element loses electron(s), it becomes _?

a cation

Which of the type of bonding is most common in the diamond structure?

covalent bond

The Earth’s upper mantle is mainly Made of peridotite, an ultramafic igneous rock with lots of olivine crystals. Which type of magma can be produced when the upper-mantle peridotite undergoes decompression partial melting along mid-ocean ridges?

basaltic

Bowen’s reaction series tells us that magic mineral such as olivine crystallize in the magma chamber at higher temperatures than felsiv minerals such as K-feldspar and quartz. If a magma undergoes fractional crystallization during cooling, the remaining magma will be _ than the parent magma.

more felsic

the periodic table is commonly used to understand the properties of elements and their compounds in earth materials. How are the elements organized in the periodic table?

in order of increasing number of protons

Polymorphism means “many forms“. In mineralogy, it means that a single chemical composition can exist with two or more different crystal structures; however, each of the structures is only stable at a certain pressure and temperature conditions. *_* and _ are examples of polymorphs.

diamond and graphite

There are three types of plate tectonic boundaries. The convergent plate boundary occurs when two plates collide against each other. Which of the following is a type of the convergent plate boundary?

subduction zone

Geologists have used the principle of uniformitarianism to understand geological activities preserved in the rock records. According to the principle of uniformitarianism, _.

geological processes we observed today have operated in the past

The Mohorovičić discontinuity coincides with the _ boundary

crust-mantle

seismic studies of the earth have shown that the planet”s interior is made of a few layers with distinct seismic signatures and chemical compositions. The major layers of the planet include (from innermost to outermost layers)

inner core, outer core, mantle, crust

Which of the following minerals is most abundant in felsic igneous rocks such as granite

K-feldspar

Magnetic mapping of the ocean floor revealed a pattern of symmetric “stripes“ which alternate polarity, centered along the mid-ocean ridges. These indicate the magnetic reversal of the Earth’s magnetic field when

the earth’s magnetic north and south poles flip

Continental and oceanic crusts cover the Earth’s crustal surface. The oceanic crust is _ than the continental crust.

denser, thinner

The Hawaiian islands are very far away from active plate tectonic boundaries, but there are active volcanoes in the region. These islands were formed _ over a period of geological times.

at a hot spot (in the intraplate)

we can classify igneous rocks by their textures and compositions. For example, felsic igneous rocks contain very high amount of K-feldspar and silica. Which of the following rocks has the highest silica content and is a felsic rock?

granite

Silicate minerals commonly exist in igneous rocks and can be used to classify the compositions of the igneous rocks. Which of the following silicate minerals in commonly found in mafic igneous rocks?

pyroxene

Melting occurs when a solid rock becomes a melt. There are a number of conditions that can cause a rock to melt. Which one of the following conditions does not cause a rock to melt in the earth’s deep interior?

an increase in pressure

Which one of the following statement about the continental drift proposed by Alfred Wegener is 1912 is TRUE?

* distribution of certain fossils inn both South American and African continents
* similarity of rock assemblages and ages across the Atlantic ocean
* “jig-saw puzzle” fit of American and African continents

Which of the following mountain ranges is the product of continent-continent convergence?

the Himalayas

Based on the plate tectonics theory, the Earth’s lithosphere is broken up into approximately a dozen pieces of large plates. Which one of the following statement is true about the plate tectonics theory?

* Lithosphere is the outer rigid shell of the Earth. The dozen pieces of the large plates are composed of the crust and part of the upper mantle
* asthenosphere is part of the mantle beneath the lithosphere (to \~ 400km in depth)
* The Plate Tectonic Theory is a unifying theory in geology like the evolution by natural selection in biology

The basic building block to all silicates are the SiO4 tetrahedra that are linked in a variety of ways in three dimensions. Which of the following statements about major silicate minerals is true?

* olivine is an abundant mineral of the upper mantle and is formed through the isolated SiO4 tetrahedra
* Mica group minerals such as biotite and muscovite and called sheet silicates because they are formed by layered SiO4
* Pyroxine is a single-chined silicate and has the representative chemical formula or MgSiO2

Iron and magnesium ions are similar in size (ionic radius) and both have a +2 positive charge. Therefore, we would expect iron and magnesium to _

substitute for each other easily in minerals such as olivine

The major classification of igneous rocks is dependent on textures and

the relative proportion of silicate minerals

Which one of the following statements about the three rock types is true?

* igneous rocks formed by crystallization from a magma, a mass of melted rock that originates deep in the crust or upper mantle
* Sedimentary rocks are commonly found on Earth’s surface
* Metamorphic rocks are formed under high pressure-temperature conditions when original rocks change forms (textures and/or mineralogy)

You find an igneous rock containing large, interlocking crystals of quartz, feldspar, and muscovite. The rock you have found is most likely a granite. Which one of the following statement about granite is true?

* granite is a felsic intrusive rock
* granite is more felsic than basalt and peridotite
* granite can be found in the enchanted rock state park in texas

Mantle upwelling in response to the plate pulling-apart at spreading (divergent) ridges results in decompression melting of the upper mantle peridotite. Partial melting of an ultramafic rock at high temperatures results in melting of mafic minerals with a basaltic composition. In which tectonic setting are you most likely to find abundant basaltic volcanism as a result of the mantle upwelling?

Spreading center (e.g., Mid-Atlantic ridge)

The volcanism at spreading centers occurs as a result of _ melting

decompression

What type of rock makes up the Columbia Plateau of Oregon and Washington?

flood basalt

Volcanic rocks derived from the Yellowstone hot spot get progressively older to the southwest. Based on this information, in which direction is the North American plate moving if we assume the hot spot source is anchored steadily deep in the mantle?

southwest

Which US city below has the highest risk of volcanic hazards such as volcanic ashes and lahars from nearby active volcanoes?

Seattle and Tacoma in the State of Washington

Magma generated in the Earth's interior rises because it is _ than the surrounding rocks

less dense

What types of lavas are most likely to be erupted at the Andes

andesitic

Which of the following statements is true about igneous rocks?

* melts are always more felsic than their parent rocks
* andesite is a fine-grained, intermediate, and extrusive rock
* Gabbro is a coarse-grained, mafic, and intrusive rock

Which statement below about sedimentary processes is correct?

* sedimentary rocks provide a record of ancient tectonic events, fossil records and evolution of life, the history of the past climate changes, among other
* sedimentary rocks are the most common rock type on earth’s surface
* sandstone is a siliciclastic sedimentary rock formed by the compaction and lithification of sediments

Lithification in sedimentary rocks include burial, compaction, and cementation. Burial of sediments results in _

increasing pressure and increasing temperature

Which of the following sedimentary rock groups are the most abundant

siltstones, mudstones, and shales

The principle of original horizontality was proposed by the danish geological pioneer Nicholas Steno (1638-1686). The principle is commonly used in studying sedimentary rocks. Which one of the following statements about the principle of original horizontality is false?

Based on the principle, younger rocks are buried under older rocks

Based on the Plate Tectonic theory, the Earth’s surface is covered by a dozen big lates. These plates are moving at an average speed of approximately _ a year

a few centimeters to ten centimeters

Metamorphic grade refers to the intensity of metamorphism in the formation of metamorphic rocks. Which one of the following geological locations do you expect to find higher-grade metamorphic rocks

continental-continental in plate boundaries where pressure and temperature are high (such as the Himalayas)

Foliated metamorphic rocks are classified by the nature of their foliation, crystal size, and segregation of minerals that are all related to the metamorphic grade. Which of the following orders has an increased intensity of metamorphism

Slate, Schist, Gneiss, Migmatite

Metamorphic facies are indicative of particular tectonic environments, and can therefore be clues to the pressure and temperature history of the rock. Geologists define the metamorphic facies by

suites of minerals that occur at certain pressures and temperature conditions

How do crystals size and foliation change with increasing intensity of metamorphism

both grain size and foliation coarseness increase

What type of metamorphism is caused by igneous intrusions

contact metamorphism

which of the following metamorphic facies represents the highest pressure typically found in subducting slabs at approximately 40 km in depth

eclogite

which of the following is the lowest grade metamorphic facies

zeolite

which one of the following geological activities can be used to predict a volcanic eruption

* earthquakes in the surrounding area of the volcano
* swelling of the volcano topography
* gas emissions from the surrounding area of the volcano dome

which mineral or minerals group occurs exclusively in sedimentary rocks? It doesn’t exist in metamorphic or igneous rocks

clay minerals

The San Andreas fault is a _ which is a result of what type of plate tectonic forces?

Transform fault, shearing forces

What type of fault does the hanging wall go down in? Which plate tectonic boundary do you expect it to occur

normal fault, divergent plate boundaries

A sample of marble has deformed brittlely during a laboratory experiment. If we wish our next sample of marble to deform plastically rather than brittlely, we should conduct the next experiment at a

higher temperature, higher confining pressure, and more water

Which of the following deformation textures/materials commonly formed along a fault deep in the Earth’s crust (at approximately more than 20 km in depth) such as that along the san Andres fault?

mylonites

What two measurements describe the orientation of a fault plane at a given location

dip and strike

In an anticline, the _ rock occurs in the center and the limbs dip *_* the center

oldest, away

Which one of the following is the best statement of the principle of original horizontality?

Sediments are originally deposited as horizontal layers (or has horizontal as possible)

The principle of superposition states that

undisturbed sediments layers get progressively younger from bottom to top

What is an unconformity in sedimentary rocks?

a gap in the geological record in sedimentary layers

A rocked formed with 1000 atoms of a radioactive parent isotope element and no daughter isotope, but contains 125 parent isotope atoms and 875 daughter isotope atoms today. If the half life of the radioactive element is 1 million years, how old is the rock?

3 million years

Which one of the following radioactive isotopes has the shortest half-life. and is good for the radioactive isotope dating of shorter absolute ages in fossils and carbonates?

carbon 14

The half life of a radioactive isotope is

the time is takes for half of the radioactive atoms to decay to daughter isotopes

What is the sequence of the geological events from youngest to oldest?

faulting, magma intrusion, deformation

What does the elastic rebound theory describe in the occurrence of an earthquake?

the buildup and release of stress (energy) during an earthquakeW

Which of the following types of seismic waves arrive at a seismic station first

primary waves

if an earthquake to occur in Austin, Texas, how long would it take for the first seismic wave to arrive at a seismograph station in Anchorage, Alaska, approximately 5000 km away?

around 8 **minutes**

Which of the following correctly lists the three rock types in order of decreasing P-wave velocity (from the rock with a higher velocity to a rock with lower velocity)

peridotite, gabbro, granite

Earthquakes that originate at depths greater than 100 km are most likely associated with _ plate boundaries

oceanic-oceanic convergent (such as the subduction zone)

Which one of the following statements about tsunamis is true?

* an early warning system for tsunamis has been developed for the Pacific region such as Japan
* Tsunamis can reach heights in excess of 20 meters when they reach the shore
* Tsunamis travel slower than P and S waves so detections of the seismic wave arrivals and amplitudes can be used in an early warning system to predict the arrivals of tsunami waves

As the distance to an earthquake increases,

the time between the arrival of the P and S wave increases

Which layer in the Earth does not transmit S waves

the outer core

The oceanic crust consists mostly of

mafic rocks

Seismic wave speeds increase with

increasing density and decreasing temperature

The Earth’s magnetic field shields the surface of the surface from

solar winds with charged particles

Which one of the following Earth systems powers the Earth’s magnetic field

the geodynamo system

Which of the following about the magnetic reversals over the geological time is correct?

* earth’s magnetic field has changed its polarity thousands of times in the Phanerozoic
* Based on the record of magnetic strength, we are in the magnetic reversal period
* Magnetic reversals typically lasted for approximately 1000 years

As seismic waves travel though the Earth , they generally

curve upward because seismic wave velocities typically increase with increasing depth

The Milankovitch cycles are dependent on Earth’s

orbital eccentricity, precession, and angle of tilt on the rotation axis

What is is Earth’s albedo?

The fraction of solar energy reflected by Earth’s surface

Compared with the visible part of the electromagnetic spectrum, Ultraviolet radiation has

shorter wavelengths and higher energy

The greenhouse effect is mainly cause by

carbon dioxide from burning fossil fuels, methane and water vapor that trap heat radiating from the Earth’s surfaceW

Which one of the following is an example for the positive feedback in the climate system

An increase in the atmospheric CO2 leads to a surface temperature increase and the global warming

Chemical analysis of ice cores from Antarctica demonstrates that as temperature increases, concentrations of atmospheric

carbon dioxide and methane both increase

In Earth’s climate system, positive feedback tends to _ changes in the system, and negative feedbacks tend to _ the system against change

amplify, stabilize

Petrolium and natural gas are considered _ energy resource

nonrenewable

Which one of the following fossil fuel burning can release the highest CO2 into the atmosphere?

coal

Which is required in an oil trap in a geological setting?

Anticlines of sandstone and shales, with shales on top

Which of the following statements regarding porosity and permeability in sedimentary rocks is true?

high porosity rocks generally have high permeability

major environment impacts of burning coal include

* the release of carbon dioxide into the climate system
* the release of sulfur that contributes to acid rain
* toxic coal ash with metal impurities

The point at which global oil production stops rising and starts to decline is called

the Hubbert’s peak

The Montreal Protocol is responsible for

phasing out CFC production

Which one of the following has dramatically changed the carbon cycle per the past 150 years

burning of fossil fuels

The Keeling Curve

shows the record of carbon dioxide in the atmosphere since 1950

Molina and Rowland proposed in 1975 that the ozone hole in the stratosphere is cause by

reaction with chlorofluorocarbons (CFCs)

Carbon sequestration

pumps carbon dioxide into the underground reservoir

How thick are the Greenland and Antarctic ice caps

Approximately 3 kilometers thick

Which one describes an accumulation of poorly sorted deposits at the end of a glacier

till

Approximately 25% of earth’s land surface is permanently frozen and covered by permafrost. If the permafrost is to be melted due to the global climate change, which could be the major consequence?

Release of methane from methane hydrate dissociation

The snow line is

the altitude above which snow does not completely melt in the summer

Movement of past glaciers can be determined by looking at the

striations