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Geology Final 2


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what kind of volcanic rock would you find at the Mid-Atlantic ridge?
pillow lava
clay materials in shale are deposited..
CaCO3, or calcite (limestone), is most soluble in which type of water?
cold water (fresh or salt)
which metamorphic facies would occur at a subduction zone (high pressure, low temperature)?
which would be the best type of index fossil for the Cambrian period?
the substudy of geology that is focused on the succession of sedimentary rock layers is:
which of the following drives the rock cycle?
internal heat of the earth
which of the following is diagnostic of minerals by itself?
x-ray diffraction pattern
which of the following sequences is listed corrected in terms of Mohs hardness scale?
apatite, quartz, corundum
which mineral crystallizes first from a mafic magma?
A geologic contact between rocks, in which the sedimentary rock was deposited on a granite
a metamorphic rock that is so high grade that it has almost melted:
which of the following has the longest half-life?
which of the following might be involved in studyign the earth?
all of the above
an example of a theory is:
1 and 2
scientists are completly objective
a website report on an experiment that was created independently and without consultation or critical review can be good science
rocks are unit composition; they cannot be broken into smaller pieces of different composition
the mineral quartz comes in many colors
a sedimentary rock can only be formed from weathering/erosion of an igneous rock
an example of a scientific law is
thermodynamic behavior
pure science is driven by:
probably the best experiment to study the history of flooding on the Mississippi River is:
dig or drill into floodplain, examine record of floods in sediments
Which of the following sounds like a good, relevant hypothesis?
"Is the center of the earth made of liquid metal, responciple for the geomagnetic field?"
The old dude who knows that a theory is never proven and can always be questioned is:
Alfred Wegener, father of plate techtonics
which of the following is NOT a mineral?
which of the following IS a mineral?
What is the building block of most of the minerals in the Earth?
silica tetrahedra
The faces of a cut gemstone reflect:
none of the above
There are thousands of minerals; but how many of these are common, rock-forming?
IS it possible for a chemical composition (like pure carbon) to come in multiple minerals; as in multiple atomic structures?
Minerals can grow, or crystalize, 1) from a magma, 2) in the solid state, and 3) from:
aqueous solutions (precipitation)
What would you find in a kimberlite pipe?
At a subduction zone, rocks melt mainly because of:
addition of volatiles (water from subducting oceanic rocks)
What causes melting at mid-ocean ridges and is responciple for producing magma that makes up all of the ocean floor?
decompression melting
why are volcanic rocks fine-grained (small crystals)?
all of the above
The first step in the cycle of forming a sedimentary rock is:
Physical properties of minerals and the tremendous variety of minerals are due to:
chemical composition and atomic structure
Chemical composition of a mineral depends on:
2 and 4 only
What type of atomic bond is strong and due to electron sharing?
covalent bond
In class, you looked at granite, rhyolite, and obsidian (3 very different rocks). Did these rocks have approximately the same chemical composition?
Mt. Pinatubo is what kind of volcano (it has ash, explosions, etc.)
composite, or strato volcano
The earth's mantle consists of a sea of a sea of magma - it is all molten below 30km depth
an igneous intrusive rock that is mafic is:
How are clastic sediments deposited?
by gravity
The composition with the least amount of silica is:
With increasing duration of sedimentary transport, what happens?
2 and 3 only
A gravel (sediment) forms what as a rock?
What is stratigaphy
layers of sediment
What is an example of an organic sediment?
Aside from composition, what else is used to classify igneous rock types?
Hawaii is made of basalt (low viscosity) and thus is a:
shield volcano
Bowen's reaction series is best defined as:
sequence of minerals that differentiates (crystallizes) from a magama as it cools
A huge, irregularly shaped igneous intrustion (like at Yosemite in CA) is a:
A pyroclastic flow forms a rock known as:
What type of sediment do you expect in the Salton Sea?
evaporite minerals
Subsidence, compaction, cementation, and chemical alteration occur during:
What rock type would you expect in an alluvial fan?
Heat and pressure increase with depth in the earth
"Arenite"; sandstone, well-sorted, mature minerals (mainly quartz), would form at:
"Shale"; mudstone, made from clay minerals, would form where?
deep ocean, far from land
Chert would form where?
deep ocean, on the sea floor
Which of the following can provide a clock by which absolute ages can be measured:
radioactive decay
Which of the following rocks would be the most usful for absolute dating
Contact metamorphism involves:
a nearby magmatic intrusion
If a limestone is metamorphosed, what rock will it become?
Which of the following is the highest metamorphic grade?
The layering and fabric in metamorphic rocks that is not the same as sedimentary layering is what?
Relative time in a stratigraphic column is based on:
2,3, 4, and 5
What makes fossils and faunal succession work, as far as being a tool relative dating and correlating stratigraphic columns?
evolution is a global phenomenon
Why can we use radioactive decay to measure absolute ages?
rates of decay are constant and measureable
Radioactive isotopes are described in terms of parent and daughter atoms.
If the half-life of Uranium-238 is 4.5 billion years, how much of the original uranium is left in the oldest Earth rocks?
just more than half
The age of the Earth is:
4.6 billion years
Why are complex names used for the relative geologic timescale?
absolute dating was not developed until mid 20th-century, so relative names were used
Placing geologic events in a sequence based on simple rules is:
relative dating
A gap within the sequence of forming layers and rocks, that can represent a large period of time is:
To what color are all galaxies shifted due to expansion of the universe?
the continental crust grew by distillation (magmatism) and amalgamation (collision) during:
Archean era
How do we know the atmosphere became oxygen rich 3.0 billion years ago?
banded iron formations
The earth's core (inner+outer) makes up:
10-20% of the earth volume
What type of plate boundary occurs between North America and the Atlantic ocean?
passive margin
Where would you find the oldest oceanic crust?
offshore VA
Which of the following is TRUE with respect to changes with increasing distances from a mid-ocean ridge?
thickness of oceanic lithosphere
At 5cm/year on the San Andreas fault, and today 600km apart, how long before LA is adjacent to Oakland?
12 million years
An example of a place dominated by normal faulting is:
Basin and Range, USA
Which of the following was a caldera eruption?
Mt. Mazama (Crater Lake), 4700 BC
If forced to live near a volcano, which might be the most useful tool in deciding where to build a home?
topographic map
When soft, wet sediments lose strenth and shift during earthquake shaking:
During which orogeny did the African continent collide with the North American continent?
The continental crust is:
thicker than oceanic crust
What would be the best place to construct a "monumant to humanity" that would survive for hundreds of millions of years?
central Canada - a craton
Scientists' best guess of how the universe was formed is called:
big bang
Our star, the sun, is a:
at least a second generation star
Which of the following is thought to have happened in the first moments of the universe:
creation of all matter
The carbon atons that make up your body were formed:
prior to a supernova in a preexisting star
What fuels the sun and causes it to radiate energy?
Why did matter accrete to form stars, solar systems, and galaxies after the big bang?
Our best guess for the origin of the moon is that it was captured intact as an astroid into the earth's orbit
4 billion years ago, or just before the "second differentation", the earth's surface was:
covered by one ocean
The first forms of life to evolve in the Archean, more than 3 billion years ago, were:
What does K-T boundary stand for?
The Cambrian Explosion represents the most intense example of what in earth history?
biologtic diversification
Where did the heat come from for the "First Differentation"?
meteorite impacts, gravitational potential energy
Why did climate change in early earth history?
removal of CO2 from the atmosphere
4 billion years ago, the length of a day was:
How do we know the length of the day during the Archean?
stromatolite fossils
How do we know the lower (younger) age limit for the time the earth formed?
moon rocks
How do we know what was going on in the earth's crust during the first stages of plate technonics?
greenstone belts
The major difference between the outer and inner core is due to:
presure-temperature and phase
The earth's inner core is:
What evidence tells us the nature of the earth's outer core?
2 and 3
The P-Wave Shadow is due to:
refraction of seismic waves at core-mantle boundary
The earth's magnetic field changes (reverses) through time.
The base of the crust is called:
the Moho
The continents are higher than the sea floor because:
What is cyanobacteria good for?
making oxygen
Most of the new oceanic crust (sea floor) is created by magmatism at:
mid-ocean ridges
North America is a "supercontinent" like Pangea
The plates in plate tectonics are:
What forms at mid-ocean ridges?
pillow basalt
10-km deep trenches in the sea floor are due to:
what is the most important thing driving plate tectonics?
mantle convection
the emergence of plate tectonics in the 1960s was a revolution for science
how old is the oldest oceanic crust?
200 million years
Plate motions are generally:
centimeters per year
The earth is expanding volumetrically due to creation of new sea floor
Which of the following would you expect at a continental collision zone?
thrust faults, folds
Are Appalachian folds actively forming?
Which word describes mountain building?
orogeny, orogenic
What instrument was most important for the revolution of plate tectonics in the 1960s?
echo sounder
What is a paleo-pole?
past position of the north magnetic pole relative to a continent held-fixed
Strike-slip faults are a part of plate tectonics because:
geometric accidents between plates
Continental crust subducts and is recycled into the mantle
Planar features along which rocks slide against each other (brittle deformation) are:
Folding occurs:
in the lower continental crust
What type of force is exerted at a collision zone?
No earthquakes greater than Magnitude 3 has ever struck the US east of the Rock Mountains
Seismologists can forecast earthquakes based on elastic strain accumulation to within:
The source area for earthquake energy in large earthquakes is:
a fault plane
Earthquake magnitude is linear; there's a 2x increase in energy released between one-step increase in magnitude
The frequency of earthquakes of a given magnitude is related to the magnitude, and decreases exponentially as magnitude increases.
Which two things exert the most important control on earthquake hazards?
location and construction (economy)
What is a killer pulse?
high energy of seismic waves near source, exponential decay with distance away
the key to eruptive style of volcanism is:
magma viscosity
Hawaii, the Columbia flood basalts, and Yellowstone are examples of what type of volcanic province?
mantle hot-spot
How are pyroclastic flows most different from simple landslides of rock?
they are always hotter
Eruption of which of the following would affect the greatest number of people?
A lahar is made up of:
the majority of rock produced by a Plinian column is:
Which of the following is a composite volcano?
Mt. Pinatubo, Philippines
Which describes the explosion of Mt. St. Helens?
edifice collapse
Geology is almost exclusively (>99%) concerned with the study of rocks

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