1.
Which of the following features only forms underwater?
Correct Answer
D. Pillow basalt
Explanation
Pillow basalt is the correct answer because it is a type of basaltic lava that forms underwater. When lava erupts into water, it cools rapidly and forms rounded, pillow-like structures. This process occurs in submarine volcanic eruptions or when lava flows into bodies of water such as oceans or lakes. The other options mentioned in the question, such as pyroclasts, pahoehoe, and volcanic breccia, can form both underwater and on land during volcanic eruptions.
2.
Ductile rocks deform by faulting
Correct Answer
B. False
Explanation
ductile deform by folding
3.
What types of plate boundaries can be found along the western coast of the US
Correct Answer(s)
D. O-C convergent
G. C-C transform
Explanation
The western coast of the US is characterized by two types of plate boundaries. One is an O-C convergent boundary, where an oceanic plate (O) is colliding with a continental plate (C). This collision causes the oceanic plate to subduct beneath the continental plate, leading to the formation of mountain ranges and volcanic activity. The other type is a C-C transform boundary, where two continental plates (C) are sliding past each other horizontally. This type of boundary is responsible for the San Andreas Fault and the frequent earthquakes in the region.
4.
Where would you expect to find earthquakes and volcanism occurring together?
Correct Answer(s)
A. O-O divergent
B. C-C divergent
C. O-O convergent
D. O-C convergent
Explanation
Earthquakes and volcanism are commonly found in areas where tectonic plates interact. Divergent boundaries occur when two plates move away from each other, creating a gap where magma rises to the surface, resulting in volcanic activity. Convergent boundaries occur when two plates collide, and depending on the type of plates involved, can lead to either subduction (O-C convergent) or collision (O-O convergent). Both types of convergent boundaries can create conditions for earthquakes and volcanism. Transform boundaries (O-O transform and C-C transform) involve plates sliding past each other horizontally, and while they can cause earthquakes, they are not typically associated with volcanic activity.
5.
Where would you expect to find only earthquakes?
Correct Answer(s)
E. C-C convergent
F. O-O transform
G. C-C transform
Explanation
In convergent plate boundaries, where two plates collide, earthquakes are expected to occur. This is because the collision of plates creates intense pressure and friction, leading to the release of energy in the form of seismic activity. Transform plate boundaries, on the other hand, are characterized by plates sliding past each other horizontally. While earthquakes can also occur at transform boundaries, they are typically less frequent and less intense compared to convergent boundaries. Therefore, in C-C convergent, O-O transform, and C-C transform plate boundaries, one would expect to find earthquakes.
6.
What type of volcano has alternating layers of lava and pyroclastic materials
Correct Answer
C. Stratovolcano
Explanation
A stratovolcano is a type of volcano that has alternating layers of lava and pyroclastic materials. These volcanoes are characterized by their steep sides and cone-shaped appearance. The alternating layers are formed as a result of repeated eruptions, where lava flows and pyroclastic materials such as ash, rocks, and gases are ejected from the volcano. Over time, these layers build up and create the distinct structure of a stratovolcano. This type of volcano is known for its explosive eruptions and can be found in various locations around the world.
7.
A (an) ____ eruption is characterized by lava flows through long, nearly vertical cracks in Earth's surface.
Correct Answer
A. Fissure
Explanation
A fissure eruption is characterized by lava flows through long, nearly vertical cracks in Earth's surface. This type of eruption occurs when molten rock, or magma, rises to the surface and erupts through a long, narrow fissure rather than a single vent. The lava flows from these eruptions can be extensive and cover large areas. Fissure eruptions are commonly associated with basaltic lava, which is low in viscosity and can easily flow through the cracks in the Earth's crust.
8.
Calderas are larger features than craters
Correct Answer
A. True
Explanation
Calderas are indeed larger features than craters. A caldera is a large volcanic crater formed by the collapse of a volcano's summit area. It is typically much larger in size compared to a crater, which is a smaller, bowl-shaped depression typically caused by the impact of a meteorite or the explosion of a volcanic vent. Therefore, the statement that calderas are larger features than craters is true.
9.
Phenocrysts are solidified fragments of volcanic material that are ejected into the air
Correct Answer
B. False
Explanation
Phenocrysts are not solidified fragments of volcanic material that are ejected into the air. They are actually large crystals that form in the magma chamber beneath a volcano before an eruption. These crystals can be carried to the surface during an eruption, but they are not fragments that are ejected into the air. Therefore, the correct answer is false.
10.
Fumaroles are hot water fountains that spout intermittently
Correct Answer
B. False
Explanation
Fumaroles are not hot water fountains that spout intermittently. Fumaroles are actually openings in the Earth's crust, often found near volcanoes, that release steam and gases such as sulfur dioxide and hydrogen sulfide. They do not typically spout water, but rather emit gases and steam due to the heat from magma beneath the surface. Therefore, the correct answer is False.
11.
Which of the following settings is LEAST likely to erupt basaltic lavas
Correct Answer
D. Oceanic plate subducting underneath continental plate
Explanation
When an oceanic plate subducts underneath a continental plate, the oceanic crust is forced into the mantle where it melts and forms magma. This magma is typically more silica-rich and less likely to erupt as basaltic lavas. Basaltic lavas are associated with oceanic plate diverging from oceanic plate and hot spot volcanism, where the magma is derived from the mantle and is more basaltic in composition. Therefore, the setting of an oceanic plate subducting underneath a continental plate is least likely to erupt basaltic lavas.
12.
A (an) ___ is a torrential flow of wet volcanic debris
Correct Answer
E. Lahar
Explanation
A lahar is a torrential flow of wet volcanic debris. This can occur when volcanic material, such as ash and rock fragments, mixes with water, either from melting snow and ice or heavy rainfall. The resulting mixture becomes a fast-moving mudflow that can travel down the slopes of a volcano, often following existing river valleys. Lahars can be extremely destructive, as they can carry large boulders and debris, causing significant damage to infrastructure and posing a threat to human settlements downstream.
13.
Which of the following items causes the most volcanic related fatalities
Correct Answer
C. Pyroclastic flows
Explanation
Pyroclastic flows cause the most volcanic-related fatalities because they are fast-moving, extremely hot currents of gas, ash, and volcanic debris that can reach speeds of up to 700 km/h. These flows can travel down the slopes of a volcano, engulfing everything in their path and causing severe burns, asphyxiation, and physical trauma. Tsunamis, lahars, ash, and floods can also be deadly during volcanic eruptions, but pyroclastic flows are particularly destructive and pose the greatest risk to human life.
14.
Volcanically active areas can be good sources of heat energy for geothermal power
Correct Answer
A. True
Explanation
Volcanically active areas can be good sources of heat energy for geothermal power because the intense heat generated by volcanic activity can be harnessed to produce steam, which in turn can be used to drive turbines and generate electricity. The heat from the volcanic activity is transferred to underground reservoirs of hot water or steam, known as geothermal reservoirs, which can be tapped into through wells. This makes volcanically active areas ideal locations for geothermal power plants, as they provide a constant and renewable source of heat energy.
15.
If all the rocks in a mountain are basalt where would this mountain be
Correct Answer
E. A large igneous province area
Explanation
A large igneous province area is the correct answer because basalt is a type of igneous rock that is commonly found in large igneous provinces. These provinces are characterized by extensive volcanic activity that results in the formation of massive amounts of igneous rocks, including basalt. Therefore, if all the rocks in a mountain are basalt, it suggests that the mountain is located in an area with a large igneous province.
16.
A granite formed with 1000 atoms of uranium-238 (a radioactive isotope). The rock now contains 500 atoms of uranium-237. How many half lives of uranium-238 have passed since the rock formed
Correct Answer
B. 1
Explanation
Since uranium-238 has a half-life of 4.5 billion years, it means that after 4.5 billion years, half of the original atoms would have decayed into uranium-237. In this case, the rock started with 1000 atoms of uranium-238 and now contains 500 atoms of uranium-237. This implies that half of the original uranium-238 atoms have decayed into uranium-237, indicating that one half-life has passed since the rock formed. Therefore, the correct answer is 1.
17.
The relative age of the granite can be calculated knowing the half life of uranium-238 is 4.5 billion years
Correct Answer
B. False
Explanation
The explanation for the answer "False" is that the relative age of the granite cannot be calculated solely based on the half-life of uranium-238. While the half-life of uranium-238 can be used to determine the age of certain rocks and minerals, it is not the only factor that needs to be considered. Other dating methods, such as radiocarbon dating or potassium-argon dating, may also be necessary to accurately determine the age of the granite. Therefore, it is incorrect to say that the relative age of the granite can be calculated solely based on the half-life of uranium-238.
18.
In which eon did humans evolve
Correct Answer
C. pHanerozoic
Explanation
The Phanerozoic eon is the correct answer because it is the eon during which humans evolved. The Phanerozoic eon spans from about 541 million years ago to the present day and is characterized by the diversification and proliferation of complex life forms, including humans. The Archean, Hadean, and Proterozoic eons precede the Phanerozoic eon and do not encompass the time period in which humans evolved.
19.
All eons encompass different amounts of geologic time
Correct Answer
A. True
Explanation
The statement is true because eons are the largest divisions of geologic time and each eon represents a significant amount of time. They are divided into smaller units such as eras, periods, and epochs, which represent shorter periods of time. Therefore, it can be concluded that all eons encompass different amounts of geologic time.
20.
You have identified an erosional surface located between gneiss (below the surface) and limestone (above the surface). What name BEST describes the erosional surface?
Correct Answer
D. Nonconformity
Explanation
A nonconformity is the best term to describe an erosional surface located between gneiss (below the surface) and limestone (above the surface). A nonconformity occurs when an erosional surface separates older igneous or metamorphic rocks from younger sedimentary rocks. In this case, the gneiss represents the older rock type, while the limestone represents the younger rock type. Therefore, the term nonconformity accurately describes the erosional surface between these two rock types.
21.
You have identified a basaltic dike in horizontal layers of a regionally extensive sandstone. what statement best describes the relationship between the dike and the sandstone?
Correct Answer
A. The dike is younger than the sandstone
Explanation
The correct answer is that the dike is younger than the sandstone. This is because a dike is an intrusive igneous rock that cuts across existing rock layers, indicating that it formed after the sandstone. The sandstone, on the other hand, is a sedimentary rock that formed from the accumulation of sediment over time. Therefore, the dike must be younger than the sandstone.
22.
What statement best describes the principle of superposition
Correct Answer
D. Undisturbed sedimentary layers get younger from bottom to top
Explanation
The principle of superposition states that in an undisturbed sequence of sedimentary rock layers, the youngest rocks are found at the top, while the oldest rocks are found at the bottom. This is because each new layer of sediment is deposited on top of the previous layers, causing the older layers to be buried deeper over time. Therefore, the correct answer is that undisturbed sedimentary layers get younger from bottom to top.
23.
Which of the following represents the smallest division of geologic time
Correct Answer
B. Epoch
Explanation
The smallest division of geologic time is an epoch. Geologic time is divided into larger units called eons, which are further divided into eras, then periods, and finally epochs. An epoch represents a relatively short period of time, usually characterized by distinct changes in the Earth's environment or the appearance or extinction of specific species. Therefore, an epoch is the smallest division of geologic time.
24.
A mass extinction is a short period in time in which a small percentage of species dies
Correct Answer
B. False
Explanation
The explanation for the given correct answer, which is False, is that a mass extinction is not a short period in time but rather a prolonged event that leads to the extinction of a significant number of species. It is not limited to a small percentage of species dying, but rather involves a substantial loss of biodiversity on a global scale.
25.
Which of the following can change the rate of radioactive decay
Correct Answer
D. Nothing changes decay rates
Explanation
Radioactive decay is a spontaneous process that occurs at a constant rate and is not influenced by external factors such as temperature, chemical reactions, or pressure. The rate of radioactive decay is determined solely by the inherent properties of the radioactive material itself and is not affected by any external conditions. Therefore, nothing can change the rate of radioactive decay.
26.
Hanging wall goes up while the foot wall goes down at a 20 degree angle, what kind of fault is this
Correct Answer
D. Thrust fault
Explanation
This fault is a thrust fault because it involves the hanging wall moving up and the foot wall moving down at an angle. In a thrust fault, the rocks on one side of the fault are pushed up and over the rocks on the other side. This type of fault is commonly associated with compressional forces in the Earth's crust.
27.
A basin is a synclinal structure with strata that dip toward a central point
Correct Answer
A. True
Explanation
A basin is a geological structure that is characterized by strata that dip towards a central point. This means that the layers of rock or sediment within the basin slope downwards towards the center of the basin. This is typically caused by the process of sedimentation over time, where material accumulates in a central area, creating a depression or low-lying region. Therefore, the statement that a basin is a synclinal structure with strata that dip toward a central point is true.
28.
In what large scale tectonic setting do fold and thrust belts form
Correct Answer
D. C-C convergence
Explanation
Fold and thrust belts form in a large-scale tectonic setting known as C-C convergence. This refers to the collision of two continental plates, where the leading edge of one plate is forced up and over the other, resulting in the formation of folds and thrust faults. The compressional forces generated during this convergence cause the rocks to deform and create these distinctive geological structures. This process is commonly observed in areas such as the Himalayas, where the collision between the Indian and Eurasian plates has led to the formation of the Himalayan fold and thrust belt.
29.
Strike describes the angle at which rocks dive into the ground
Correct Answer
A. True
Explanation
The statement "strike describes the angle at which rocks dive into the ground" is true. In geology, the term "strike" refers to the orientation or direction of a rock layer or fault line on the Earth's surface. It is measured as the angle between the line formed by the intersection of the rock layer or fault with a horizontal plane. The strike provides important information about the geological structures and helps in understanding the formation and movement of rocks.
30.
What type of deformation texture best describes a myloniite?
Correct Answer
E. Cataclastic
Explanation
A mylonite is a type of rock that forms through cataclastic deformation, which involves the crushing and grinding of rocks along a fault zone. This type of deformation texture is characterized by the presence of finely crushed and fragmented rock fragments, giving the rock a granulated appearance. Therefore, cataclastic is the best type of deformation texture that describes a mylonite.
31.
Which of the following structures has the youngest rocks at its edges
Correct Answer
C. Dome
Explanation
A dome is a geological structure where the rocks are folded upward, forming a circular or elongated feature. The youngest rocks are found at the edges of a dome because they are the most recently uplifted and exposed to erosion. Over time, erosion wears away the older rocks, leaving the younger rocks exposed at the edges of the dome. This is why a dome has the youngest rocks at its edges.
32.
Which of the following is not evidence for continental drift
Correct Answer
D. Earthquakes at transform plates
Explanation
Earthquakes at transform plates are not evidence for continental drift. While earthquakes do occur at transform plate boundaries, they are a result of the movement of tectonic plates along these boundaries, rather than evidence for the concept of continental drift. Continental drift is supported by evidence such as fossil distribution, rock assemblage distribution, and the jig saw puzzle fit of continents, which provide geological and biological evidence for the movement of continents over time.
33.
Geologic maps are color maps that represent rock formations exposed at earth's surface
Correct Answer
A. True
Explanation
Geologic maps are color maps that represent rock formations exposed at the Earth's surface. This means that they provide a visual representation of the different types of rocks and their distribution in a particular area. By using different colors and patterns, geologists can identify and classify the various rock formations, helping to understand the geological history and processes that have shaped the Earth's surface. Therefore, the statement "geologic maps are color maps that represent rock formations exposed at Earth's surface" is true.
34.
In which of the following settings would you expect to find volcanism and earthquakes
Correct Answer
C. O-O Divergence
Explanation
O-O Divergence refers to the boundary where two oceanic plates move away from each other. This setting is commonly associated with volcanism and earthquakes as the separation of the plates allows magma from the mantle to rise and create new crust. This process leads to the formation of mid-ocean ridges and volcanic activity. The movement of the plates also generates stress and friction, resulting in earthquakes along the divergent boundary. Therefore, it is expected to find volcanism and earthquakes in the O-O Divergence setting.
35.
Which of the following statements about supercontinents is false
Correct Answer
A. The supercontinent Columbia formed more recently than the supercontinent Rodinia
Explanation
The statement that the supercontinent Columbia formed more recently than the supercontinent Rodinia is false. Rodinia existed between 1.3 billion and 750 million years ago, while Columbia existed between 1.8 billion and 1.5 billion years ago. Therefore, Rodinia formed more recently than Columbia.
36.
Plate area decreases at divergent plate boundaries
Correct Answer
B. False
Explanation
At divergent plate boundaries, the plates move away from each other, creating a gap. As the plates separate, magma rises from the mantle and fills the gap, forming new crust. This process is known as seafloor spreading. The creation of new crust at divergent boundaries actually leads to an increase in plate area, rather than a decrease. Therefore, the given statement is false.
37.
Which rocks do scientists look at to study magnetic anomalies
Correct Answer
C. Basalt found on the seafloor
Explanation
Basalt found on the seafloor is the correct answer because scientists study magnetic anomalies using a method called paleomagnetism. Basalt contains magnetic minerals that align with the Earth's magnetic field as it solidifies. By studying the orientation of these magnetic minerals in basalt samples, scientists can determine the past positions of the Earth's magnetic poles and track the movement of tectonic plates over time. Since basalt is commonly found on the seafloor, it provides a valuable source of information for studying magnetic anomalies and plate tectonics.
38.
All tectonic plates move across earth at the same rate
Correct Answer
B. False
Explanation
The statement "all tectonic plates move across earth at the same rate" is false. Tectonic plates are large pieces of the Earth's lithosphere that move and interact with each other. They do not move at the same rate, but rather at different speeds and directions. This movement is driven by the process of plate tectonics, which involves the motion of the underlying mantle. The rate of plate movement can vary from a few centimeters to several centimeters per year, depending on the specific plate and location.
39.
What formula is used to calculate seafloor spreading rates
Correct Answer
A. Speed= distance/time
Explanation
The formula used to calculate seafloor spreading rates is speed = distance/time. This formula calculates the speed at which the seafloor is spreading by dividing the distance it has spread by the time it took to spread that distance. By using this formula, scientists can determine how quickly the seafloor is moving and gain insight into plate tectonics and the geological processes occurring beneath the ocean's surface.
40.
In which setting will a volcanic island arc form
Correct Answer
E. O-O convergence
Explanation
A volcanic island arc forms in the setting of O-O convergence. This refers to the convergence of two oceanic plates, where one plate subducts beneath the other. As the subducting plate sinks into the mantle, it begins to melt, creating magma. This magma then rises to the surface, forming a chain of volcanic islands. This process is commonly observed in regions such as the Pacific Ring of Fire, where several volcanic island arcs exist.
41.
In which setting will the tallest mountains be created
Correct Answer
A. C-C convergence
Explanation
C-C convergence refers to the collision of two continental plates, resulting in the formation of tall mountains. When two continental plates collide, they push against each other, causing the crust to buckle and fold, leading to the formation of mountain ranges. This process is responsible for the creation of some of the tallest mountains on Earth, such as the Himalayas and the Alps. Therefore, in the setting of C-C convergence, the tallest mountains are created.
42.
In which setting will rift valleys form
Correct Answer
D. C-C divergence
Explanation
Rift valleys form in a setting of C-C divergence. This is because C-C divergence occurs when two continental plates move away from each other. As the plates separate, tensional forces cause the lithosphere to stretch and thin, resulting in the formation of a rift valley. This process is commonly observed in regions such as the East African Rift System, where the African Plate is splitting apart.
43.
What kind of force(s) is (are) responsible for strike slip faulting
Correct Answer
C. Shearing
Explanation
Shearing forces are responsible for strike-slip faulting. In strike-slip faults, the two blocks of rock move horizontally past each other, causing the rocks to slide and shear along the fault plane. This type of faulting occurs when there is a lateral or horizontal movement along the fault line, and the shearing forces acting on the rocks are responsible for this movement. Tension and compression forces are more commonly associated with other types of faulting, such as normal and reverse faults.
44.
The study of layers in sedimentary rock is known as
Correct Answer
C. StratigrapHy
Explanation
Stratigraphy is the study of layers in sedimentary rock. It involves analyzing the different layers of rock to understand the geological history and sequence of events that have occurred over time. By examining the composition, thickness, and arrangement of these layers, stratigraphy helps geologists interpret past environments, climate changes, and the formation of fossils. Geochronology, on the other hand, focuses on determining the age of rocks and fossils, while paleontology studies the fossils themselves. Sedimentation refers to the process of deposition and accumulation of sediment.
45.
Which of the following is the best statesment of the principle of original horizontality
Correct Answer
C. Sediments are deposited as horizontal layers
Explanation
The principle of original horizontality states that sediments are deposited as horizontal layers. This means that when new sediment is deposited, it tends to settle in a flat, horizontal position. Over time, these layers can become compacted and lithified to form sedimentary rocks. This principle is important in understanding the relative ages of rock layers and the processes that shape the Earth's surface.
46.
The smallest division of geologic time is the era
Correct Answer
B. False
Explanation
The statement is false because the smallest division of geologic time is not the era, but rather the epoch. The geologic time scale is divided into eons, which are further divided into eras. Each era is then divided into periods, and each period is divided into epochs. Therefore, the era is not the smallest division of geologic time.
47.
What is an unconformity
Correct Answer
A. A gap in the geologic record
Explanation
An unconformity refers to a gap in the geologic record, where there is a discontinuity in the layers of rocks or sedimentary deposits. This gap can occur due to erosion, tectonic activity, or non-deposition of sediment over a period of time. Unconformities are significant in studying the Earth's history as they represent missing periods of time and can provide insights into past geological events and changes in the environment.
48.
Which of the following is an erosion surface that separates two sets of sedimentary layers with non parallel bedding planes
Correct Answer
D. Angular unconformity
Explanation
An angular unconformity is an erosion surface that separates two sets of sedimentary layers with non-parallel bedding planes. This type of unconformity occurs when older tilted or folded sedimentary rocks are eroded and then overlain by younger, horizontally deposited sedimentary rocks. The angular unconformity represents a significant gap in the geologic record and indicates a period of deformation and erosion before the deposition of the younger sedimentary layers.
49.
Which of the following statements about radioactivity is false
Correct Answer
D. Energy is consumed during radioactivedecay
Explanation
Radioactive decay is a spontaneous process in which the nucleus of an atom undergoes disintegration, resulting in the emission of radiation. During this process, energy is released, not consumed. Therefore, the statement "energy is consumed during radioactive decay" is false.
50.
A rock formed with 1000 atoms of a radioactive parent element, but contains only 250 radioactive parent atoms today. If the half-life for the radioactive element is one million years, how old is the rock?
Correct Answer
A. 2 million years old
Explanation
The half-life of a radioactive element is the time it takes for half of the atoms of the parent element to decay into the daughter element. In this case, the rock started with 1000 atoms of the radioactive parent element and now contains only 250 radioactive parent atoms. This means that half of the original parent atoms have decayed. Since the half-life of the radioactive element is one million years, it would take two million years for half of the parent atoms to decay. Therefore, the rock is 2 million years old.