GEOL EXAM 2
hale is metamorphosed into three rock types: (1) a banded gneissic rock; (2) a rock with small mica crystals with a shiny aspect; (3) a very shiny rock with large mica crystals; and (4) a dull slate with cleavage. Which of the following lists these rocks in order of increasing metamorphic grade?
4, 2, 3, 1
Which of the following sites has volcanoes related to subduction? A is on an island arc, B is in the Andes, C is near Hawaii, D is along a mid-ocean ridge.
A and B
What event triggered the main eruption of Mount St. Helens May 1980?
A landslide removed rocks and released pressure on the magma.
What are some factors that could allow flood basalts to have high-volume eruptions?
A large amount of magma is generated in the mantle, magma rises to the surface along thick dikes, and the magma is hot and has a low viscosity.
Which are true of faults?
A lateral fault may result from horizontal compression, orientation of a fault depends on directions of stresses, vertical compression may result in a more vertically oriented fault.
This photograph shows chalk. How is it formed?
Accumulation of microscopic organisms composed of calcium carbonate.
Which of the following activities is NOT used to monitor volcanoes?
All of these are used to monitor volcanoes.
A fold in which rock layers warp up in the shape of an A is an...
Anticline.
Which of the following are locations where flood basalts are known to have occurred?
Brazil, India, Siberia, and ocean plateaus.
Which of the following is a location in which flood basalts erupted?
Columbia Plateau
Which of the following is a valid statement about how rocks respond to stress?
If a rock has strained, then it has changed its size or shape.
What is the geologic setting of Vancouver, British Columbia?
It is along the Fraser River and its delta.
Which of the following is a good interpretation of the environmental significance of an attribute of a sedimentary rock?
Large cross beds in well-sorted sandstone usually indicate deposition by wind.
Which of the following are NOT differences between an eruption column and pyroclastic flow?
Pyroclastic flows form from a higher gas flux
Which of the following is common in lava flows associated with scoria cones?
Some scoria cones are not accompanied by a lava flow and vice versa and some lava flows squeeze out near the base of the scoria cone.
Which of the following occurs in a lava tube?
The surface of the lava flow solidifies to form a roof over the moving lava, lava tubes insulate a lava flow, allowing it to flow farther, and if a lava tube drains, it becomes a tube-shaped cave.
Which of the following is NOT true of calderas?
They are produced by removal of easily eroded pyroclastic materials.
Which of the following is a common characteristic of carbonate rocks?
They commonly have a dissolved appearance.
Which of the following are true for horsts and grabens?
They may form associated with multiple normal faults, a graben is a block that is dropped down relative to blocks on either side, and a horst is a block that is uplifted relative to blocks on either side.
Lahar
a destructive mudflow on the slopes of a volcano.
The eruption that occurred on Mount St. Helens was triggered by...
a huge landslide, caused a lateral blast that knocked down trees and buildings.
A formation is defined as...
a rock unit that is distinct and laterally traceable
High fluid pressure in a rock body will...
act to decrease the confining pressure
What types of rocks would be common in a composite volcano?
all of the above
Which of the following is a typical way in which siltstone and shale are expressed in the landscape?
all of the above
How many people were killed by the 1883 eruption of Krakatau, Indonesia?
almost 40,000
If bubbles cannot escape easily from a magma, the resulting eruption is likely to...
be explosive.
Determine the possible environments of deposition for the yellowish-tan sandstone.
beach and a river system
A single volcano may produce...
both explosive and nonexplosive eruptions
Which of the following is most likely to deposit a conglomerate?
braided river
Which of the following is most likely to occur at shallow crustal levels?
brittle deformation
Volcanic mudflows can be detected remotely by monitoring...
characteristic rumbling produced as they rush down valleys.
What type of rock would you form in this plant-rich swamp?
coal
Which of the following does NOT correctly match a rock with a possible environment in which that rock forms?
coal-deep-sea organic-rich black shale
The crater at Crater Lake was formed by...
collapse of overlying rocks into an emptied magma chamber.
The classic volcano shape is displayed by...
composite volcano
This relatively large, symmetrical volcano contains interlayered lava flow, pyroclastic deposits, and volcanic mudflows. What kind of volcano is it?
composite volcano
Folds are most often created through what type of stress?
compression
Which of the following characterizes a continental rift?
contact metamorphism near magma chambers, normal faults, tension, and metamorphism associated with shearing.
Which of the following plate boundaries is least likely to produce composite volcanoes?
continent-continent convergent boundary with a high mountain range (Himalayas)
Above which type of plate tectonic boundary is Mount Rainier located?
convergent
Which environment is most likely to deposit a breccia?
debris flow
Which of the following sites would most likely have turbidity currents?
deep seafloor at D
These sandstone beds are interlayered with dark marine shales. What is the most likely environment in which the sandstone formed?
deep-water turbidity currents
A sandstone with a pinkish or reddish color that is the result of oxidation of iron-bearing minerals indicates the sand was...
deposited on land and exposed to air.
Which of the following features is probably the same age as fault 2?
deposits along the fault
Carbonate rocks exposed at the surface in wet environments will...
dissolve and weather readily.
Which of the following types of volcanic eruption have occurred on Mount St. Helens since it began erupting in 1980?
eruption column, pyroclastic flow, and volcanic dome.
This igneous rock contains flattened pieces of pumice and small crystals of quartz and feldspar. What type of eruption probably formed this rock?
eruption of a pyroclastic flow that forms a thick and hot deposit
Fractures along which the rock has slipped relative to the other side are called...
faults
The deep-sea floor is characterized by sediment dominated by...
fine dust and the remains of single-celled organisms.
Which of the following is NOT a typical characteristic of a volcano?
flat-topped mesa with eroded volcanic rock cliffs at that top
Which represents the largest igneous eruptions on Earth?
flood basalts
Which of the following processes produce sedimentary clasts?
fracturing of bedrock that results in angular pieces, breaking of round cobbles as they are transported, scouring and abrasion of bedrock along rivers, decomposition of granite into quartz grains and clay.
Which of the following is NOT a rock typically found within calderas?
gabbro
Choose those statements that correctly describe limestone.
gray or yellowish in color, commonly includes shells, is known as a carbonate, and forms in water from various processes.
In what environments does high pressure/low temperature metamorphism occur?
in a subduction zone or accretionary prism
Which of the following commonly precede a volcanic eruption?
increased gas flow from a volcano, steam eruptions from the volcanic crater, and increased heat flow from the volcano.
Fractures that are simple cracks where the rock has pulled apart by a small amount are...
joints
Which of the following structures can be related to or can occur close to faults?
joints, tilted blocks, anticlines, and synclines.
Volcanic mudflows (lahars) are common on composite volcanoes because...
large amounts of rain and snowmelt mix with loose ash on steep slopes.
Which of the following features is younger than fault 1?
lava flow and granite
Lithifies can be defined as...
loose sediment hardens into sedimentary rock.
Long, thin lava flows are typically produced by...
low-viscosity lavas
Which of the following might a geologist look for in a rock hand sample to make interpretations regarding deformation and metamorphism?
mineral chemistry, minerals that are present, and observed sequence of minerals.
Compared to a younger scoria cone, an older scoria cone would have...
more soil and plants.
What tectonic setting is interpreted to be the cause of volcanism at Yellowstone?
movement of North America over a mantle plume
Which of these volcanic hazards associated with Mount Rainier is the most dangerous to nearby population centers?
mudflows
This relatively small volcanic feature consists of solidified lava and some volcanic ash. What kind of volcano is it?
none of the above
Shield volcanoes are built up primarily by relatively...
nonexplosive outpourings of lava.
The two main processes by which sediment is produced are...
physical and chemical weathering.
Peat forms from the accumulation of...
plant material
Which of the following resources do sedimentary deposits or rocks NOT commonly host?
platinum
Which of the following is NOT a typical match between the type of eruption and resulting rock type?
pyroclastic flow-scoria
Which of the following is NOT a common type of cement in sedimentary rocks?
pyroxene
Rocks rich in what mineral tend to have a poor solubility during weathering?
quartz
The most likely cause of graded bedding found in sedimentary rocks is...
reduction in water current velocity.
This dark gray igneous rock is glassy and elsewhere contains small vesicles and flow bands. What type of rock is this?
rhyolite or obsidian
Determine the possible environments of deposition for the upper sandstone and mudstone unit.
sandy beach or delta
This volcano is relatively small and composed of volcanic cinders. What kind of volcano is it?
scoria cone
Which of the following lists the four types of volcanoes shaped like hills and mountains?
scoria cone, shield, composite, dome
Which of the following rocks is composed of the smallest sedimentary clasts?
shale
Which of the following matches a sedimentary rock with a possible metamorphic equivalent?
shale-slate
Which of the following are forms of differential stress?
shear, compression, and tension.
common in landscapes formed by carbonate rocks...
sinkholes, fractures widened by dissolution, well-defined layers (beds), and outcrops with pits or holes.
When lava flows reach the ocean, they...
solidify and add land to an island
Mountain streams and rivers typically are characterized by...
steep gradients and are confined by bedrock canyons.
Which of the following situations would result in angular clasts?
steep slopes in a mountain
The typical form for a composite volcano is a...
steep-sided cone
Loose debris on a rock-exposed landscape is known as...
talus.
Some scientists think that Yellowstone could cause a future disaster because...
the area is part of a caldera, scientists think that magma is still present at depth, past eruptions from Yellowstone carried ash over a huge area of western North America, and land near Yellowstone is uplifting in some places and subsiding in others.
Sedimentary environments on land differ because of variations in...
topography, local geology, amount of water
Sedimentary environments on land differ because of variations in...
topography, local geology, and amount of water.
Changes in topography, water chemistry, and gas output all are used to help predict...
volcanic eruptions
The uniformly sized sand shown here would be described as...
well sorted
