Geo 303 final (hw questions)
Order the composition of magmas by their complete melting temperatures, from lowest temperature to highest.
1(highest) - ultramafic 2- mafic 3- intermediate 4- felsic
Refer to the mathematical formula in the previous question. If the gravitational force between two meteorites in outer space is 1 unit when they are 1 km apart, what is the gravitational force if the same meteorites are separated by 3 km?
1/9 unit
How much stronger is a magnitude 6 earthquake compared with a magnitude 4?
100
What is the age of the oldest intact rocks that have been found on Earth?
4 Ga (billion years)
Over the past 30 thousand years, what has been the relationship between the North magnetic pole and North geographic (rotational) pole?
Although the magnetic pole is constantly moving in random directions, it always stays near to the rotational pole.
The force of gravity is proportional to (m1 x m2) / r2, where m is mass and r is distance. Suppose that you weighed yourself at the Equator, and again at the North Pole. You would weigh less at the Equator because:
At the North Pole, the distance r between your center of gravity and the earth's center of gravity is shorter than at the Equator
Why do atoms naturally arrange themselves into crystal structures?
Because crystal structures represent a low-energy arrangement for atoms
Why is amphibole considered a "garbage can" mineral?
Because it can take in a lot of cations with odd sizes and charges that other minerals don't want
What type of stress is primarily responsible for the growth of the Himalayas?
Compression
Which of following lists the features in increasing order of the amount of magma that would be required to form them?
Dike, laccolith, pluton, batholith
What type of magma is best for generating a caldera-forming eruption?
Felsic
. Which statement best agrees with the Airy model for isostasy?
High topography regions have thicker crust than lower relief areas
Which statement best agrees with the isostasy model of G.H. Pratt?
High-elevation regions have lower-density crust than lower elevation areas.
Match the type of silicate with its relative temperature of crystallization in the discontinuous part of Bowen's Reaction Series.
Highest temperature (~1400 °C) isolated tetrahedra High temperature (~1200 °C) single chain Intermediate temperature (~1050 °C) double chain Low temperature (~900 °C) sheet
Darwin's Theory of Evolution tries to provide an explanation for:
How life diversified after it originated
In which setting is one most likely to find a gabbro?
In an ophiolite complex (oceanic crust pushed onto a continent)
Why does the mineral olivine take in either Fe or Mg into the same location in its crystal structure?
Iron and magnesium have about the same ionic radius
Which of the following is true of a batholith?
It cools slowly and contains relatively large crystals
How do we know that Enchanted Rock in Central Texas was formed at depth?
It is made of granite containing large crystals
. How does the Doppler Effect tell us about the motion of galaxies?
Light from galaxies moving away from us has a lower frequency (i.e. looks redder) than light from galaxies that are moving toward us.
Imagine a mountain range supported by a low-density root zone (Airy's hypothesis). What is the isostatic response as rivers erode the mountain away?
The mountains and root zone rise, and the mountains become lower as the root zone also diminishes.
Which of these factors are involved in determining whether X-rays will reflect off of parallel internal planes in a crystal structure (i.e. Bragg's Law) to create a dot in a diffraction pattern? Select all that apply.
The spacing between the planes The wavelength of the X-rays The angle between the incoming X-rays and the planes
Which of the following are forms of deformation?
Tilting Folding Faulting
Wegener's proposal that the continents had once fit together as a single supercontinent was criticized for many reasons, but in the end it was rejected by scientists at the time because
Wegener could not provide a driving force strong enough for continental drift.
The low seismic velocity zone is caused by
a change in rigidity of the mantle in the asthenosphere
The difference between a hypothesis and theory is
a hypothesis is a suggested explanation, a theory is supported by numerous lines of evidence
The asthenosphere is known from
a low velocity zone in the upper mantle
The Hawaiian Hot Spot is:
a rising mass of hot material under the Pacific plate, that is stationary while the plate moves over it, making volcanoes in whatever part of the plate happens to be over it at a given time.
A steinkern (German: "stony heart") of a snail is:
a solid object that has the form of the interior of the snail shell
What is isostasy?
a state of gravitational equilibrium maintained by a block of lithosphere that "floats" in the underlying mantle at a level determined by both its density and its thickness;
what the heck is a Wadati-Bennioff zone?
a zone of earthquakes occurring with depth in the subducting lithospheric plate
According to current scientific understanding, the age of our universe is:
about three times older than the age of the Earth
Choose the one statement that best describes foliation.
an alignment of mineral grains perpendicular to the direction of compression
In a typical granite, the crystals usually don't have nice facets because they grow into and interfere with each other, resulting in them being:
anhedral
If a sedimentary rock consists of the shells of an organism, which of the following type of sedimentary rock is it?
biochemical
Pure marble and quartzite are nonfoliated metamorphic rocks because
both are dominated by minerals that produce equant grains.
The two types of chemical sedimentary rocks are
carbonate, silicate
The two main types of sedimentary rocks are:
clastic and chemical
Wegener saw Pangaea as a jigsaw puzzle, where the puzzle pieces were
continents
Of the bonds discussed in class, the strongest in minerals is the
covalent
Identify the factors that cause melting and magma formation Choose one or more
decompression addition of volatiles crystallization heat transfer
What factors control the cooling time of magma within the crust? Choose as many as are correct.
depth at which the magma cools the heat difference between the magma and the surrounding rock the volume of the intruded magma
The earth is referred to as a layered planet because:
differentiation during and following planetary accretion allowed the materials making up the early Earth to separate based upon their density;
the elastic rebound theory states that
earthquakes occur when the rock strength is exceeded, releasing elastic energy stored during elastic deformation
The Moho and the base of the lithosphere are the same
false
The smallest structural unit describing the repeating pattern in a minerals crystal structure is the unit cell. True or false?: the chemical formula for the unit cell is the same as that of the mineral.
false
Choose the most likely product of partially melting a rock of intermediate composition? hint: think about what components melt first and what the melt composition will look like
felsic magma
select all of the following that are a mineral
graphite and diamond
in volcanic island arcs (e.g., associated with ocean-ocean collisions), the magma for volcanism comes from where?
hydration melting of the upper mantle
The earliest matter in the universe was composed of mostly:
hydrogen and helium
the deepest earthquakes occur?
in subducting plates
The youngest oceanic crust in the Atlantic is located
in the center - at the mid ocean ridge
Mafic minerals are defined as such by having which elements in them?
iron and magnesium
Within the eroded remains of a single mountain range,
it is possible to find a variety of metamorphic rocks produced in distinct facies, including high-, intermediate-, and low-grade rocks.
The polarity of the Earth's magnetic field in the geologic past is
known to have experienced numerous reversals, as shown by remnant magnetization of iron-rich minerals in rocks.
What does grain size generally indicate about the cooling of a melt. Choose one
larger crystals indicate that the melt cooled gradually
Compared to the average density of the mantle, the average density of the continental crust is:
less
Earthquakes don't always recur on the same interval because of which of the following (select all that apply)
local rock strength can change the rate of buildup of stress on a rock may evolve differently an earthquake may release variable amounts of accumulated stress
In Wegener's evidence for continental drift, continents were proposed to fit together, such as the east coast of South America with the
lower west coast of Africa.
If you were using both a compass and a map marked with latitude and longitude to navigate, you might note the angle difference between your compass and what is marked as North on the map, called
magnetic declination.
Plate movement is influenced by each of the following EXCEPT
mantle plumes, which are created when hot rock rises up from the deep mantle and creates melting at the base of the lithosphere.
The way atoms are arranged in a crystal depends on all of the following except:
mass of the ions
Evidence that the South American and African continents were once joined includes evidence from their coastlines such as
matching fossil distributions.
Earthquake intensity is measured on what scale
mercali scale
Marine magnetic anomaly belts run parallel to
mid-ocean ridges.
Identify which statements are true about earthquakes (select all that apply).
most earthquakes occur along plate boundaries most earthquakes are the consequence of plate tectonics an estimated one million earthquakes occur each year, but most are small
New lithosphere is created in which of the following settings
nowhere - mass balance says that crust cannot be created or destroyed
deep (>100km) earthquakes can occur in which of the following environments (select all the correct answers)
ocean-continent collisions ocean-ocean collisions
Which of the following processes is LEAST important in generating the components necessary for the formation of sedimentary rocks
photosynthesis
which tectonic processes are likely to be associated with very deep earthquakes? choose all that apply
plate subduction
The apparent tendency of the north (or south) magnetic pole to vary in position over time is termed
polar wander.
With increasing metamorphic grade, rocks from a given protolith will tend to become
poorer in water
Which of the following minerals are you most likely to find in a mature sediment eroded from a continental landmass?
quartz
Select all answers that are correct about the lithosphere
rigid outermost tectonic plates comprised of the crust and uppermost mantle
Chemical weathering would be expected to be highest in which of the following?
rocks that have been broken up by intense physical weathering
Which of the following is NOT an example of a chemical sedimentary rock
sandstone
Which of the following silicate groups may be hydrous (include the hydroxyl ion in their crystal structure)? Check all that apply.
sheet silicates double-chain silicates
Which of the following classes of minerals are most abundant in the Earth's crust and mantle?
silicates
Which of these locations is an example of a continental rift
the East African Rift
Obsidian is a volcanic glass that forms when lava cools very quickly to a solid. Why is it not classified as a mineral?
the atoms in obsidian are not arranged in a crystal structure
What information can meteorites provide about Earth? (select all that are correct)
the average composition of the whole Earth an upper boundary for the Earth's age the composition of Earth's core Which two discoveries are attributed to Edwin Hubble
Which correctly described the aesthenosphere?
the ductile part of the mantle
The surface location of an earthquake is called
the epicenter
Glacial isostatic rebound refers to
the isostatic rebound associated with the retreat of large ice sheets since the last glacial maximum
The Moho is:
the observation that seismic waves speed up below the crust mantle boundary in association with a compositional change
The fact that the outer core is liquid is known from
the s-wave shadow
Archaeopteryx, a Jurassic fossil that is the earliest known bird, retained many characteristics inherited from its immediate ancestors, which were:
theropod dinosaurs
An ultramafic rock is most likely to represent which geological environment?
The mantle
The Earth's layers are composed of which of the following, from outside to inside:
(Si,Al,O); (Mg,Fe,Si,O); (Fe,Ni)
All of these things are believed to be true of pegmatites, except one. Which is the exception?
Required millions of years for crystals to grow so big
Sulfate minerals are those that are organized around which ion?
SO42-
5. What is the most probable origin of Earth's moon?
The Moon condensed from material expelled from a gigantic collision between the proto-earth and a Mars-size impacting body
Why do the minerals in a geode form euhedral crystals rather than anhedral grains?
The crystals have abundant room to grow within a rock cavity
All of the following statements about the atmosphere of the early Earth are correct, except one. Which statement is incorrect?
The development of Earth's magnetic field caused the atmosphere at that time to be driven off.
Which of the following is true of effusive eruptions as compared with explosive eruptions?
The magma in effusive eruptions contains less silica than in explosive eruptions
This satellite image shows the Himalaya Mountains, the tallest mountain range on Earth, and the Tibet Plateau. Which of the following processes is responsible for the formation of the mountains in this region?
thickening of the crust caused by deformation during collision
The severity of shaking during an earthquake depends upon all of the following except
time of day of the earthquake
Particle size is used as an indicator of maturity (or the distance its constituent parts have traveled since being eroded out of their host rocks) in clastic sediments and rocks. This is because:
water tends to both break down particles, making them smaller, and sort them by size based on their transportability
Which of the following correctly lists the steps describing how a clastic sedimentary rock forms from its pre-existing parent rock from first to last?
weathering, erosion, transportation, deposition, lithification
The presence or absence of cleavage in a mineral indicates
whether there are planes through the crystal structure with relatively sparse and/or weak atomic bonds;