geology mid exam
Drag the appropriate labels to the geological features on the map below. Keep in mind that the darker blues represent deeper water.
left to right: - fracture zone - abyssal plain - continental shelf - mid-ocean ridge
Label the image with the features of tectonic plates.
left to right: - moho - continent - continental crust - continental shelf - lithospheric mantle - asthenosphere - abyssal plain - oceanic crust
Label each target on the map below with the name of the appropriate geological feature.
left to right: - mountain belt - ice sheet - continental shelf - plain
The lithosphere and asthenosphere are known as physically different layers of the Earth because they behave very differently when deformed. Sort the items below into the correct boxes based on characteristics of the lithosphere and asthenosphere.
lithosphere: - mantle and crust - brittle - colder asthenosphere: - mantle only - ductile - warmer
Which of the following traps cosmic rays and shields life on the Earth from excessive radiation?
magnetosphere
Which of the Earth's layers accounts for most of the volume of the Earth?
mantle
Label the atoms in the silica-oxygen tetrahedron shown in the image below
middle: silicon red balls: oxygen
Identify outcomes of physical weathering. Choose one or more: A. clay minerals B. more rounded fragments C. chemically altered minerals D. smaller fragments
more rounded fragments smaller fragments
The center of a mid-ocean ridge is where
new oceanic lithosphere is created.
The two most common gases of the Earth's atmosphere, and their percentages, are
nitrogen (N2) at 78%, and oxygen (O2) at 21%.
According to current plate tectonics theory,
plates are composed of the crust and the uppermost part of the mantle.
After an explosive volcanic eruption on an island, the surrounding sea is full of light-gray, floating rock. What must it be?
pumice
Which of the following terms has to do with extrusive igneous activity?
pyroclastic
An unknown mineral scratches glass, has only average specific gravity, and shows no cleavage but does show conchoidal fracture. Which of the following could it be?
quartz
Which of the following variables could influence the width of marine magnetic anomalies on the floor of the ocean?
rate at which the plates are moving away from the mid-ocean ridge duration of the magnetic polarity event
Which of the following fits the definition of a mineral?
salt, because it's crystalline
Bowen's reaction series
shows that minerals in a cooling magma crystallize in a predictable order.
The silica-oxygen tetrahedra is the building block of which chemical class of minerals?
silicates
Which of the following classes of minerals are most abundant in the Earth's crust and mantle?
silicates
Which of the following pairs of elements composes most of the Earth's crust?
silicon and oxygen
During World War II, the military imaged the seafloor by sending pulses of sound waves down through the water and measuring the time it took for the sound to bounce off the seafloor and return to the receiver. This method is called
sonar.
When you scrape a mineral along a ceramic plate to observe the color of its powder, you are checking the physical property known as
streak
The Earth's magnetic field is created by
the flow of liquid iron in the Earth's molten outer core.
The great varieties of minerals on the Earth are classified by mineralogists into a small number of groups on the basis of
the negative ion or ionic group in their chemical composition.
The genetic scheme for classifying rocks is based on
the origin of formation.
The global occurrence of earthquakes reveals that
they usually occur on the boundaries of plates or at hot spots.
This figure shows air temperature values in the layers of the Earth's atmosphere. Identify each layer by dragging the labels to the correct spot on the figure.
top to bottom: - thermosphere - mesosphere - stratosphere - trophosphere
Identify the statement that is true about the Big Bang.
It began with all matter and energy concentrated in an infinitesimally small point.
What would be the significance of finding a precipitated mineral on another planet?
The planet may have or have had liquid water on it.
Why are there so many different types of magma?
The source rock from which magmas form may differ. Different magmas may mix to form a new magma.
Which of the following is a characteristic of all rocks?
They are a collection of minerals or a body of glass
The Himalayas are growing because
a continental plate is colliding with another continental plate there.
A mineral, as geologists understand the term, is a naturally occurring solid substance with a definable chemical composition and
a fixed crystalline structure.
The island of Hawaii is the youngest, and the islands get progressively older to the northwest. Plate tectonic theory explains this as
a hot spot currently sitting under Hawaii and the Pacific Plate moving across it in a northwesterly direction.
graphite is
a polymorph of diamond.
Biogenic minerals are minerals produced by living organisms. Two commonly seen biogenic minerals are _____________, which is often produced by coral and other invertebrates, and ____________, which often makes up the shell material of mollusks such as clams.
aragonite calcite
Pillow basalts
are formed in a submarine environment.
The classification of igneous rocks depends on both grain size and silica composition. Using your knowledge of this information for the igneous rocks listed, place the rock names in the correct positions on the chart.
basalt: fine, mafic diorite: fine, intermediate gabbro: fine, mafic peridotite: coarse, ultramafic rhyolite: fine, felsic
Wegener's theory of continental drift took decades to be accepted
because Wegener couldn't explain how continents moved.
Humans are part of the
biosphere.
Label the block diagram of the lithosphere appropriately.
bottom to top: - asthenospheric mantle - lithosphere - moho - continental crust - oceanic crust
Place the label that identifies the correct layer of the Earth on the following diagram.
bottom to top: - inner core - outer mantle - lower mantle - upper mantle - crust
Label the polarity chrons with the appropriate title and polarity. Note that some of the chrons contain short-duration subchrons. The boundaries between the chrons are indicated by the heavy black lines. The thickness of layers on this diagram represents the duration of time during which the layer accumulated.
bottom to top: - oldest reversed polarity interval - oldest normal polarity layer - reversed polarity chron that lasted the longest - youngest normal polarity layer
Identify outcomes of chemical weathering. Choose one or more: A. more rounded fragments B. smaller fragments C. chemically altered minerals D. clay minerals
chemically altered minerals clay minerals
The tendency of a mineral to break and produce smooth, curving, shell-shaped surfaces is termed
conchoidal fracture.
Sort outcomes of continental collision versus those related to ocean-ocean (oceanic) convergence.
continental collision: - crustal thickening - mountain building oceanic convergence: - subduction - volcanism
Identify the four tectonic settings of igneous activity.
continental rift, hot-spot volcano, mid-ocean ridge, subduction zone
Modern plate tectonic theory was developed in what decade?
1960s
The early view of the Earth's interior layers resembled a hard-boiled egg. Identify the correct labels for this simplified view.
1: crust, 2: mantle, 3: core
Which of the following statements about hardness is true?
A copper penny will scratch gypsum.
Which of the following methods of heat transfer occurs when an increase in temperature creates a decrease in density, causing the warm, less dense material to rise, as shown in this diagram?
convection
Intrusive igneous rocks
cool slowly and are coarse-grained.
Which type of chemical bond occurs when atoms share electrons, as shown in this diagram?
covalent
Drag and drop the mineral names to the correct position on this graph of the Mohs hardness scale. (Note that in this graph the actual hardness is plotted on the vertical axis.)
diamond: highest talc: lowest
According to the theory of plate tectonics, the plates are: Choose one or more:
discrete pieces of lithosphere which move with respect to one another. moved by the creation of new crust and subduction of old crust.
Determine whether the rock is felsic, intermediate, mafic, or ultramafic.
felsic
As magma cools and minerals begin to form, the composition of the resulting magma becomes more
felsic.
The earliest nebulae to form in the Universe were made almost entirely of
hydrogen and helium.
When magma or melt solidifies it forms _______ rocks. If a pre-existing rock is exposed to extreme heat or pressure its physical properties can change, forming a(n) ___________ rock. Rocks derived from the weathered grains of other pre-existing rocks through lithification are _________ rocks.
igneous metamorphic sedimentary
The crystallization of salt from evaporating seawater
is an example of precipitation from a solution.
A crystalline rock
is composed of interlocking minerals that grew together.
Granite
is felsic in composition.
Felsic (or silicic) magma
is more viscous than mafic magma.
The boundary between the lithosphere and the asthenosphere
is the boundary between rigid mantle and plastic mantle.
Classify the silicate groups based on how many oxygen atoms are shared by each silicon-oxygen tetrahedron with a neighboring silicon-oxygen tetrahedron. To see a larger version of the image, scroll down.
isolated tetrahedra: 0 single chain: 2 double chain: 2 or 3 two-dimensional sheet: 3 three dimensional framework: 4
The hardness of a mineral is determined by
its ability to resist being scratched by other substances.
The Earth is round because
its interior rock is warm enough to flow slowly in response to gravity.
In which tectonic setting would you most expect to find igneous activity?
landward of oceanic trenches
Order the steps that lead to assimilation.
1) A magma forms and begins to migrate through the crust. 2) Blocks of the surrounding silica-rich crust break off and become incorporated into the magma. 3) Incorporated crustal blocks within the magma melt, mixing with the magma. 4) The amount of silica in the magma increases and the magma composition changes accordingly.
Order the events chronologically that occurred in the formation of our Solar System.
1) An accretionary disk formed. 2) A protosun formed. 3) Rings formed in the protoplanetary disk. 4) Planetesimals collected to the protoplanets.
Order the steps involved in fractional crystallization.
1) Magma, after entering through the bottom of the magma chamber, reaches the top of the chamber where temperatures are lower. 2) Magnesium- and iron-rich minerals begin to crystallize. 3) Mineral crystals, having a higher density than liquid magma, sink to the bottom of the magma chamber. 4) The magma shifts toward a more intermediate composition.
Place in chronological order the events that led to the formation of the Earth.
1) The Earth cleared its orbit of all other matter, making it a true planet. 2) The Moon formed. 3) Volcanic activity occurred, releasing gases. 4) An atmosphere formed.
Place in chronological order the events that led to life as we know it on Earth.
1) The oceans formed. 2) Photosynthetic organisms appeared on Earth. 3) Oxygen (O2) accumulated in the atmosphere. 4) Multicellular life developed rapidly on Earth.
Order the compositions of magmas produced via melting from lowest temperature to highest. What composition of magma is produced by melting at lower temperatures? At higher temperatures?
1) felsic 2) intermediate 3) mafic 4) ultramafic
Rank the following steps describing how a clastic sedimentary rock forms from its pre-existing parent rock.
1) weathering 2) erosion 3) transportation 4) deposition 5) lithification
As the map below shows, the oldest seafloor is generally less than 200 million years old. Why?
All oceanic lithosphere eventually gets subducted beneath the continents by the time it is 200 million years old.
Magmas can have a variety of chemical compositions for which of the following reasons? Choose one: A. All of the possible answers are correct. B. Two magmas may mix together to form a third of differing composition. C. Source rocks undergo varying degrees of partial melting, producing magmas of a different composition than the rock. D. Melts may come from different source rocks.
All of the possible answers are correct.
What physical characteristics can be used to distinguish individual rock types? Choose one: A. the size and shape of grains that compose the rock B. texture C. All of the possible answers are correct. D. composition
All of the possible answers are correct.
Which statement(s) is true about igneous rocks? Choose one: A. They were molten and have frozen into a solid form. B. They may form from lava. C. They may form around volcanoes. D. All of the possible answers are correct.
All of the possible answers are correct.
Sort the following rock examples into their appropriate rock group based on texture.
Amorphous - a rock with no crystal or grain structure Clastic - a rock derived from weathered sediments - a rock formed by lithification Crystalline - a rock with identifiable mineral crystals - a rock formed by the slow cooling of magma - a rock formed by the precipitation of water
Which of the following statements are true about partial melting?Choose one or more: A. Mafic components of the parent rock tend to go into the liquid state first during partial melting. B. As more of the rock melts during partial melting, the magma becomes more mafic than the original melt that formed. C. Felsic components of the parent rock tend to go into the liquid state first during partial melting. D. Partial melting results in magmas that are more felsic in composition than the parent rock.
As more of the rock melts during partial melting, the magma becomes more mafic than the original melt that formed. Felsic components of the parent rock tend to go into the liquid state first during partial melting. Partial melting results in magmas that are more felsic in composition than the parent rock.
Which statement accurately describes the relationship between air pressure and altitude, as illustrated in this figure?
At the top of Mt. Everest, air pressure is 30% of what it is at sea level (altitude of zero).
Identify the true statement. Choose one: A. The series of rock stripes perpendicular to and bilaterally symmetric across the mid-ocean ridge records the sequence of the Earth's magnetic reversals over time. B. Positive magnetic anomalies occur where seafloor basalt has the same polarity as Earth's present-day magnetic field. C. All polarity chrons are the same length of time; they differ only in the magnetic strengths they represent. D. The width of each rock stripe is a measure of how long the polar direction took to change.
B. Positive magnetic anomalies occur where seafloor basalt has the same polarity as Earth's present-day magnetic field.
Identify the true statement. Choose one: A. The only two planets with moons are the Earth and Jupiter. B. Our Sun is the only star we know of that has planets associated with it. C. The composition of the giant (Jovian) planets is mainly gas and "ice." D. The Sun accounts for almost 50% of the Solar System's mass.
C. The composition of the giant (Jovian) planets is mainly gas and "ice."
Order the steps of continental volcanic arc formation.
Convergence begins 1) A subduction trench forms where the subducting plate bends downward into the mantle. 2) An accretionary prism begins to form. 3) Magma, created by flux melting of the mantle, rises through the continental lithosphere. 4) Lava erupts onto the surface, forming volcanoes.
Order the steps of volcanic island arc formation.
Convergence begins 1) A subduction trench forms where the subducting plate bends downward into the mantle. 2) An accretionary prism begins to form. 3) Magma, created by flux melting of the mantle, rises through the overriding plate. 4) Lava erupts onto the surface, forming volcanoes.
Silicate minerals Choose one: A. are the most common minerals on the Earth. B. have a silicon-oxygen tetrahedron as their structural unit. C. are classified by the manner in which the silica tetrahedra are arranged. D. All of the possible answers are correct.
D. All of the possible answers are correct.
What does grain size generally indicate about the cooling of a melt?
Larger crystals indicate the melt cooled gradually
Which statements are true about lava? Choose one or more: A.Lava is molten rock that has been erupted onto the surface of the Earth. B.Lava composition can vary greatly among different types of volcanoes. C.Lava is molten rock beneath the surface of the Earth. D.All lavas originate with the same composition that is then changed over time.
Lava is molten rock that has been erupted onto the surface of the Earth. Lava composition can vary greatly among different types of volcanoes.
Which of the following statements about lithosphere and asthenosphere is true?
Lithosphere consists of the crust and the upper mantle and behaves like a rigid layer that breaks or bends rather than flowing like the asthenosphere.
Compare and contrast the melting of water and rock by matching each statement to the appropriate category below.
Melting of Water - The composition stays the same. Melting of Rock - Partial melting can take place. Applies to Both - A change of state takes place. Applies to Neither - This phase change takes place at 100°C.
Identify statements true of Pangaea. Choose one or more:
Pangaea was one of several supercontinents that have formed and broken up during Earth's history. Rates of seafloor spreading in the Atlantic Ocean are compatible with what is known about the breakup of Pangaea. The regional-scale folds visible in the Appalachian Mountains are remnants of Pangaea's formation.
Order the steps in continental rift formation.
Rifting Initiates 1) The lithospheric mantle begins to stretch horizontally and thin vertically. 2) The crust fractures, and faults develop. 3) Large fault blocks of crust slide down into the widening rift. 4) Magma erupts as lava, creating volcanoes along and near the center of the rift.
Order the steps that lead to seafloor spreading.
Rifting initiates 1) The asthenosphere beneath diverging plates rises and melts. 2) A magma chamber forms beneath the ridge axis. 3) Magma rises to the surface and erupts via submarine volcanoes. 4) Newly formed crust is moved laterally away from the ridge.
Label each of the following minerals with the correct mineral class.
Silicate (SiO44-): quartz Sulfide (S2-): pyrite Oxide (O2-): magnetite Halide (Cl-): halite Carbonate (CO32-): calcite Native metal: copper Sulfate (SO42-): gypsum
Which of the following statements regarding the Big Bang theory are true?
The Universe is considerably older than Earth. All matter in the Universe was once confined to a single point.
Obsidian is a volcanic glass that forms when lava cools very quickly and consists of a solid mass of glass through and through. Why is obsidian not classified as a mineral? Choose one:
The atoms or molecules in obsidian do not have a crystalline structure.
Which of the following statements about differentiation are true?
The mantle formed as a result of differentiation. The core formed as a result of differentiation.
Categorize processes related to transform boundaries. Sort the following processes those likely to be related to a transform boundary or those likely associated with other boundary types.
transform boundary: - earthquakes other boundary: - divergence - convergence - subduction
The heavier elements on the Earth (those with atomic numbers greater than 5)
were formed by stellar nucleosynthesis during the life cycles of older stars and supernovae.