Geology Midterm Study

Which of the following would *NOT* be associated with a Normal Fault?

"Pencil test" indicates space being taken-up/an overlap between two sections of a previously continuous layer

Set up a scale model of the Earth, where the Earth is the size of a ping pong ball. You want to calculate how large Mars should be. What **FOUR** variables do you need to do 'step one' of the procedure by setting up the equation?

1. Diameter of ping pong ball 2. Diameter of Mars 3. Diameter of Earth 4. Diameter of the scale model of Mars

Geology is useful for understanding and developing solutions for which of the following critical issues?

1. Water 2. Climate 3. Energy 4. Mineral resources 5. Hazards 6. All of the above

If all of geologic time was the length of a football field, human civilization would be _____(this far)______ from the end zone.

Two hair's breadth; thimble (0.5 tsp); Grand Rapids

What is the best definition of a protolith?

A rock (any type) that a metamorphic rock was before it got metamorphosed

How many reversals has Earth's magnetic field undergone during the last 4.5 million years?

21

Which arrows best show the forces that would be associated with tension?

<-- --->

Which of the following is not an example of deformation?

A change in lithology

Why is geology important?

A knowledge of basic geology helps people solve economic, environmental, health, and safety challenges. Yes! A basic knowledge is important for everyone... even non-geologists!

Melting at a subduction zone is due to...

Addition of water/sediments (flux melting)

A strong magnetic field is *important* for ALL of these, EXCEPT....

Answer - Moving the lithosphere during plate tectonics Helping retain Earth's atmosphere and water Generating the northern lights Protecting the Earth from solar winds

Which of the following is *NOT* one of the drivers of plate motion?

Answer: Earth's rotation Slab pull Mantle convection Ridge push

Which of the following is a naturally occurring rock?

Answer: None of these Asphalt Concrete Brick

Which of the following does NOT strongly influence the rate of cooling of molten rock?

Answer: the temperature at which melting began whether it stays underground (intrusive) or erupts (extrusive) the size of the magma body the shape of the magma body

Place the following sedimentary processes in order -- starting with "Any type of rock" & ending with "A clastic sedimentary rock".

Any type of rock Weathering Transportation Deposition Lithification A clastic sedimentary rock

Why didn't the early Earth have liquid water?

At greater than 1,000º C, water would be in its gas phase This is the answer! Temperature constraints come from evidence for differentiation.

What type of radioactive decay, important in the transition from radioactive parent Rb-87 to its stable daughter Sr-87, occurs by giving off an electron?

Beta

Which theory explains the formation of the Universe?

Big bang

________ deformation is when the change in shape or size from applied forces occurs by breaking a rock

Brittle

Which of the following is another reason why we typically don't use carbon dating for rocks?

Carbon's half-life is too short

Which three of these are the main layers of the Earth - as defined by chemical composition?

Core Crust Mantle

How does a larger data set (going back further than 4.5 million years) change our idea of if we're "due" for a reversal? Cretaceous (~85-124 Ma): top description Most recent 30 million years (or so): middle description Jurassic (around 155 Ma): bottom description

Cretaceous: Reversals happened less frequently, if we are like this time, our current duration is MUCH shorter than the average and maybe we're not "due" Most recent 30 million years: Reversals happened at about the same frequency as our 4.5MY data set, if we are like this time, our current duration is longer than the average and maybe we're "due" Jurassic: Reversals happened more frequently, if we are like this time, our current duration is MUCH longer than the average and maybe we're way past "due"

Place the following descriptions where they match their compositional layer. Crust = top description. Mantle = middle description. Core = bottom description

Crust:Silicates - mostly Si & O, sometimes bonded with other light elements, like Al, Ca, and K. Mantle: Iron-magnesium silicates - for example: Olivine (Fe, Mg) SiO4 Core: Iron-Nickel Alloy - mostly metallic Fe, ~5% Ni

Which of these is the best definition for "natural resource"?

Earth materials that can be used for economic and/or industrial purposes.

Which of the following statements is TRUE?

Even though their relative motion is sliding past each other in opposite directions, the North American Plate & Pacific Plate are both moving in a somewhat westerly direction in a absolute sense

All geologic processes can be summarized by those included in the classic "rock cycle".

False

From the point where access to the land has been granted to the point where you're ready to remove a natural resource from the ground is fairly quick and inexpensive.

False

Only people who plan to major in geology should take a geology course.

False

When a radioactive isotope has not yet reached one half-life, it is very difficult to determine its age.

False

Match the composition with its characteristics. (Read carefully - they're not necessarily in a particular order.) Top - Felsic 2nd - Ultramafic 3rd - Mafic Bottom - Intermediate

Felsic: The most silica (Si, O), least iron & magnesium (Fe, Mg), light in color - mostly whites/pink with ~10-20% black minerals Ultramafic: The least amount of silica (Si, O), most iron & magnesium (Fe, Mg), dark in color - made of black and green minerals Mafic: A low amount of silica (Si, O), a high amount of iron & magnesium (Fe, Mg), dark in color - made of black and gray minerals Intermediate: A medium amount of silica (Si, O), a medium amount of iron & magnesium (Fe, Mg), both dark and light - made of about 50% black and 50% white/pink minerals

Put the following grain sizes in order from largest (top) to smallest (bottom).

Gravel Sand Silt Clay

Which of the following properties is **NOT** particularly unique to Earth?

Gravity

What topic areas does a physical geology course cover? (select all that apply)

Hazards Resources Earth's subsurface Earth's surface

Which metamorphic setting results in a relatively high increase in pressure, but lower temperature conditions?

High pressure metamorphism (subduction zones)

Match the following definitions with the terms (put them in the proper order). Top: Hypothesis Middle: Theory Bottom: Scientific Law

Hypothesis: A reasonable idea that has the possibility of being correct, but has not yet been proven. Theory: A scientific idea supported by an abundance of evidence that has passed many tests and failed none. Scientific Law: Principles of science that must be true; if they were violated, the physical world would not behave as we see it.

For which type of rock do we typically find numerical ages?

Igneous

Which of the following statements is FALSE?

In the age of the internet, discerning valid sources of information from pseudoscience and misinformation is easy because only peer reviewed information tends to be shared.

Which FOUR elements make up more than 90% of the mass of the Earth?

Iron Oxygen Silicon Magnesium

A car honking their horn at you is traveling away from you, what happens to the sound due to the Doppler effect?

It has a lower pitch

How does the texture of sedimentary protolith quartz sandstone change when it becomes a non-foliated metamorphic rock (quartzite)?

It looks more crystalline

What observation could you make that would support the Big Bang theory?

Light from distant galaxies is red-shifted

After a sediment has been transported and deposited, what process in the rock cycle turns it into a sedimentary rock?

Lithification

A piece of what Earth layer makes the "plate" of plate tectonics?

Lithosphere (crust + the uppermost mantle)

Place the following descriptions where they match their physical layer. Lithosphere = top description. Asthenosphere = 2nd description. Mesosphere = 3rd description. Outer core = bottom description. Inner core = Solid

Lithosphere: Solid - brittle, rigid Asthenosphere: Solid - ductile, plastic, gooey Mesosphere: Solid - stiff but not brittle Outer core: Liquid Inner core: Solid

Our current polarity duration is ____longer or shorter___ than the average field state duration for the last 4.5 million years?

Longer

Match the following rock types with their associated methods of identification (first steps). Mineral - top description Igneous rocks - 2nd Sedimentary rocks - 3rd Metamorphic rocks - bottom

Mineral: Look at properties like: color, luster, and cleavage. Test the sample hardness. Test if it is magnetic or reacts with HCl. Igneous Rocks- Look for a visible texture based on the size of mineral grains & estimate composition by looking at the proportions of light vs. dark minerals. Sedimentary Rocks- Look to see if the rock appears to be made of pieces or is one uniform mass. Look at the size of pieces if they're there and test for mineral composition by hardness and reaction to HCl. Metamorphic Rock- Look for layers or stripes that might indicate an alignment of mineral grains. Look for evidence of fusing of grains/recrystallization textures. Test hardness and reaction to HCl for composition, if there is no evidence of alignment of grains.

Mineral - top description Igneous rocks - 2nd Sedimentary rocks - 3rd Metamorphic rocks - bottom

Mineral: Produced by any of the methods listed here Igneous rocks: Solidifying from a melt Sedimentary rocks: As a product of weathering, precipitation and/or deposition and lithification Metamorphic rocks: Alteration as a result of increased pressure and/or temperature

Which theory explains the formation of the solar system?

Nebular

Does Earth's magnetic field reverse itself periodically (at equally-spaced time intervals)?

No

Which layer of the Earth is liquid?

Outer core

In one of your assigned lecture readings this week, the report lists some case studies where natural resources are closely intertwined with political stability and security.

Pakistan Mexico Afghanistan Somalia (the Gulf of Aden) Yemen

Which TWO observations can we use to determine that the seafloor gets older, symmetrically, as you get further from a mid-ocean spreading center? (select 2)

Paleomagnetic reversal patterns recorded in seafloor basalts The thickness of marine sediments

Which of the following are the five criteria to be a mineral? (choose 5)

Particular chemical composition Solid Naturally occurring Inorganic Ordered atomic arrangement

A mineral is distinct from a compound due to its...

Particular ordered atomic arrangement

What happens to cause melting during decompression melting?

Pressure decreases

Which mineral is the hardest among the ones that we have focused on for rock-forming minerals in our identification techniques?

Quartz

Which of the following is one reason why we typically don't use carbon dating for rocks?

Rocks don't have enough carbon

Which type of seismic wave is a body wave whose particle motion is perpendicular to the wave propagation direction?

S-wave

Rank the following rocks from their un-metamorphosed sedimentary protolith (top) up to the highest grade, partially melted foliated metamorphic rock (bottom).

Shale Slate Phyllite Schist Gneiss Migmatite

Which description matches the observations for a divergent boundary?

Shallow earthquakes, highest values for heatflow on the planet, new seafloor formed along shallow underwater ridges

Which description matches the observations for a transform boundary?

Shallow earthquakes, seafloor not formed nor recycled, offsets in topography along fault zones

Which description matches the observations for a convergent boundary (continental-continental)?

Shallow to intermediate earthquakes, world's tallest (non-volcanic) mountains

Arguments could be made for Venus or Mars to be the most Earth-like out of the terrestrial planets. Which of the following characteristics are more Earth-like for Venus?

Size and density

Put the following events in order from oldest (happened first) on top to most recent (happened last) on bottom.

The big bang Previous sun to ours goes supernova, creating certain elements Our sun ignites at the center of our solar nebula Gravitational pull and spinning causes a disk shape of dust/gasses to form around our sun Earth and the other planets accrete and/or fling debris from their orbit

Which of these is the best definition for "mining"?

The extraction, from the Earth, of valuable material for societal use.

Which description matches the observations for a convergent boundary (subduction zone)?

The full range of shallow to deep earthquakes, seafloor recycled, deepest ocean trenches near explosive volcanoes

Which of the following statements is FALSE?

The magnetic field, generated by moving, molten iron in the Earth's asthenosphere, often records a horizontally oriented field during a reversal

Which of these is the best definition for "sustainability"?

The practice of using natural resources responsibly, so they can support both present and future generations.

What happens to cause melting during flux melting?

The solidus is lowered by a change in composition

Which of the following statements is FALSE?

The study of earthquakes only goes back about 100 years and scientific evidence indicates earthquakes will continue only for another 100 years before ceasing.

Which of the following ARE ways we can study the DEEP interior of the planet? (select ALL that apply)

Theoretical mineral physics Scaling experiments Earthquake (seismic) wave speeds Experimental mineral physics

Geophysicists aren't certain how long it takes for a reversal to switch from one polarity to the other, but estimate that it must be less than 10,000 years. By examining the ages on either side of the reversals recorded in this data set, explain how they came up with this estimate.

There are samples with Normal and Reverse polarity age dated to within 10,000 years of one another (like at 1.67, 2.01 and 3.40 MY), so the time it took at have a reversal must have been less than 10,000 years.

Which of these is the best definition for "ore"?

When a valuable material is found in high enough concentration that it can be extracted for a profit.

Which type of mass movement is a pyroclastic flow?

a debris avalanche

Which type of mass movement is a lahar?

a mudflow

Which type of mass movement is associated with a talus slope?

a rock fall

Near the headwaters of a stream, rivers __________________.

are split into several smaller tributaries

Without the element phosphorus, organisms wouldn't have the nutrients they need for _________.

bones

Discharge is ________________.

calculated by multiplying the average velocity, depth, and width of a stream

When a mineral breaks in such a way that it shows a curved broken surface, we say it has _____________.

conchoidal fracture

Geologic _____________ are built by interpretation and extrapolation of the observed age and orientation of rock layers that outcrop at the surface and examining road-cuts and/or the sides of river gorges to view layers and structures from their side. In places where outcrops and side views are rare, _____________ and making correlations between the recovered rock layers and conducting geophysical surveys, either at the surface or within boreholes, is also important.

cross-sections; drilling holes

What seismic waveform value can be used to determine the station's distance from the epicenter?

difference between the P-wave arrival and the S-wave arrival

What is the name of the process for separating light and heavy elements, active during early Earth formation, that is responsible for developing a compositionally layered Earth structure?

differentiation

Folds (including anticlines, synclines, basins, and domes) are a result of __________ deformation

ductile

Flooding is _______________.

essential for supplying sediments necessary for counteracting compaction and subsidence of land in delta regions like the Mississippi

Geologists, geochemists, and geophysicists are typically employed by companies for the ____________ and production ("upstream") end of the resource supply chain.

exploration

Volcanic eruptions at a subduction zone are...

explosive

Pyroclastic flows, ash fall, and lahars are associated with ________________.

explosive eruptions

Which of the following is NOT considered to be a "natural resource" as we defined them in lecture?

farmed vegetables

It is sometimes difficult to tell the difference between a _____________ rock and a non-clastic sedimentary rock. Darker gray to black in color is more common in shale, so color might help... or, unless it is chert, most of the non-clastic sedimentary rocks won't scratch glass.

fine grained sedimentary

Typically, a geologic map will show...

formation names in order from youngest at the top, getting older as you go down (and to the right if there are multiple columns)

Earthquakes occur ___(1)___ along plate boundaries and ____(2)____ in the intraplate setting.

frequently; rarely

Stratovolcanoes are _______________ than shield volcanoes.

smaller and steeper

What's the shortest amount of time that the magnetic field remained unchanged in polarity, and when did this occur?

less than 10,000 years - 30,000 years; Normal at 2.01MY

Magma at a subduction zone is..

more felsic

Magma at a subduction zone is...

more viscous (blocky, chunky spew)

The color of ___________ is a little misleading and doesn't accurately represent its composition, it is dark, but felsic.

obsidian

The difference between an anticline and a syncline might be noticed by...

oldest vs. youngest at the fold axis limbs dipping away vs. towards the fold axis U-shaped vs. A-shaped cross-section

Granite has a _________________ igneous texture and a ____________________ composition.

phaneritic felsic

Which of the following terms are NOT typically used to describe luster? Choose all that apply.

pink cubic light or dark

Pyroclastic flows and lahars typically flow along ___________.

preexisting drainage systems (rivers)

What geological resources are important for Michigan's economy (specifically airplane/car part manufacturing, casting)?

sand and iron ore

Which type of ground would experience the most amplification of seismic waves and/or potentially experience liquefaction (depending on the fluid pressure in the pore space)?

silt, mud

What are we actually calculating the age of when we're using radioactive decay to calculate an age? The moment a certain mineral with a certain amount of known starting atoms _____________.

solidified from a melt

The difference between an anticline and a dome might be noticed by...

straight-line contacts vs. circular contacts in map-view limbs dipping away from the fold axis vs. dipping away from a central point

Volcanoes at a subduction zone are...

stratovolcanoes (composite volcanoes)

What property is particularly useful (diagnostic) for identifying if a rock or mineral is made of Calcite?

test if it reacts with hydrochloric acid

What is the main difference between creep and slumping?

the nature of the moving mass: a grain-by-grain movement vs. movement of a coherent block of material

A "100-year flood" occurred along a certain stream last year, the chances of having another "100-year flood" in that same area this year are _______________.

the same as last year (a 1% chance)

What is the main difference between a rock slide and a rock fall?

the surroundings: movement down a slope vs. free-fall off a cliff

What is the main difference between an avalanche and a flow?

the type of material that moves: debris mixed with air vs. debris mixed with water

Predicting ____(1)_______ is much easier than predicting _____(2)_______.

volcanic eruptions; earthquakes

In one of your lecture videos, Dr. Mike Wise of the Smithsonian uses which THREE (3) of these techniques to study pegmatites?

x-ray diffraction electron microprobe scanning electron microscope