Geology Exam 2
________ are steep-sided hills composed mostly of stratified drift
Kames
How is the thickness of the lithosphere going to change as it moves away from a divergent plate boundary?
Lithosphere will thicken as more mantle is added.
Which of the following statements explains why the presence of Mesosaurus in both South America and Africa supports the continental drift hypothesis?
Mesosaurus was a freshwater aquatic reptile with fossil remains in both South America and Africa.
How do plates move at convergent plate boundaries?
Plates move towards each other.
Playa lake
center of basin where streams flow and briefly accumulate before evaporating or infiltrating bedrock
Course-grained sediments such as pebbles and cobbles often comprise the ________ in desert environments.
desert pavement
Salt flat
encrusted salt layer left behind once water evaporates
Identify the depositional glacial feature indicated by the letter E in the above block diagram.
end moraine
Which of the following is NOT a variety of moraine?
hanging
What are cross beds?
inclined layers in sediment or sedimentary rocks that reveal the direction of wave or wind transport
Identify the depositional glacial feature indicated by the letter D in the above block diagram.
kettle lakes
Which glacial feature indicates the maximum extent of a glacier?
terminal end moraine
What evidence first indicated to scientists that the continents were once connected?
the apparent jigsaw-like fit of continents together, as in the case of South America and Africa
Which glacier deposit are drumlins mainly composed of?
till
Which one of the following most accurately describes the volcanoes of the Hawaiian Islands?
volcanoes fed by a long-lived hot spot below the Pacific lithospheric plate
What is the most important erosional agent in deserts?
water
Where is the world's largest ice sheet located today?
Antarctica
Which of the following is a layer of the Earth that is classified NOT by composition, but by physical properties?
Asthenosphere
How did core samples drilled from various locations in the ocean floor support the concept of seafloor spreading?
Cores containing younger sediment were located closer to the ridge crest than were cores containing older sediment, meaning that older material is continuously being pushed away from the ridge.
Define dry climate. How extensive are the desert and steppe regions of Earth?
Dry climate is a climate in which yearly precipitation is less than the potential loss of water by evaporation. Desert and steppe regions cover about 30 percent of Earth's land surface.
Which of the following statements characterizes ephemeral streams?
Ephemeral streams flow only at certain times of the year.
The cross bedding in a preserved layer of sandstone dips (tilts downward) to the East. What can be inferred about the wind direction at the time of deposition?
From West to East
Which of the following responses best defines the movement of ice within a glacier?
Glacial movement is always in a downslope direction.
_______ are long, linear scratch marks carved onto bedrock by glacial abrasion.
Glacial striations
What is the main material being subducted at an ocean-continent convergent boundary?
Oceanic lithosphere
________ was a supercontinent that existed in the late Paleozoic era of geologic time.
Pangaea
__________ are defined as a chain of glacial lakes where each lake flows into the next.
Pater noster lakes
How do plates move at divergent plate boundaries?
Plates away from each other.
How do plates move at transform plate boundaries?
Plates move side-by-side in opposite directions.
Before the 1960s, how did geologists view the ocean basins and continents of the Earth?
Scientists believed that all ocean basins and landmasses were permanently fixed in their positions.
What were two aspects of Wegener's continental drift hypothesis that were objectionable to most Earth scientists?
Scientists objected to the driving force behind plate tectonics, which Wegener claimed to be the gravitational forces of the Sun and Moon, and his claim that continents traveled by plowing through oceanic crust.
How is desert different from steppe?
Steppe is more humid than desert.
Which of the following pieces of evidence supports the plate tectonic theory?
The stripe patterns of high- and low-intensity magnetism are mirror images on both sides of an oceanic ridge.
When a valley glacier leaves the mountains and enters the relative flat lands below, it may spread out to form ________.
a piedmont glacier
When desert pavement is produced in a desert, why do the larger particles accumulate on the surface?
The wind can move particles of only a very specific size and it takes away these small particles, concentrating the larger ones
A(n) ________ is a cone of debris that forms where an ephemeral stream emerges from the confines of the canyon. Its runoff spreads over the gentler slopes at the base of the mountains and quickly loses velocity, dumping most of its sediment load within a short distance.
alluvial fan
Bajada
an apron of sediment along a mountain front created by the coalescence of alluvial fans
What is the largest type of glacier?
an ice sheet
What is an ephemeral stream?
an intermittent stream that carries water only in response to specific episodes of rainfall
With regards to ancient climates, Wegener's continental drift hypothesis states that 300 million years ago,
areas in North America, northern Africa, Europe, and Asia produced tropical swamps along the equator while areas in South America, Africa, India, Australia, and Antarctica were glaciated at the South Pole.
Identify the alpine glacial features indicated by the letter C in the above block diagram.
arête
What glacial feature is circled in Figure 1?
arête
What is the difference between till and stratified drift?
Till is an unsorted type of glacial drift, whereas stratified drift is sediment that is sorted according to the size and weight of particles.
In an area of alpine glaciation, sinuous, sharp-edged ridges called ________ and sharp, pyramid-like peaks called ________ are common features.
arêtes; horns
The ________ is weaker and less rigid than the overlying lithosphere.
asthenosphere
Compared to the Earth's asthenosphere, the Earth's lithosphere is
cooler and more rigid.
What is the name used for cracks in the upper portion of a glacier?
crevasses
A rainshadow desert forms ________.
in places where mountain ranges act as barriers to the movement of water vapor
This cobble shows prominent scratches because ________.
it was scraped against other rocks in a glacier
Identify the depositional glacial feature indicated by the letter C in the above block diagram.
kames
Inselberg
large bedrock knobs projecting above a sediment-filled basin
Deflation may lead to ________.
loess dust storms desert pavement
A ________ is a long-lived, stationary, magma source deep in the mantle, well below the base of the lithosphere.
mantle plume
Which of the following is an example of a glacial deposit?
moraine
What forms at divergent plate boundaries?
new oceanic lithosphere
Linear, magnetic patterns associated with mid-ocean ridges are configured as ________.
normal and reversed magnetized strips roughly parallel to the ridge
In general, where do volcanoes form in subduction zones?
on the overriding plate, away form the convergent boundary
Oceanic lithosphere contains oceanic crust and the __________.
outermost part of mantle beneath the oceanic crust
Most of Earth's seismic activity, volcanism, and mountain building occur along ____________.
plate boundaries
A(n) ________ is defined as a semiarid climate.
steppe
Alfred Wegener included all of the following lines of evidence as supporting his "continental drift" hypothesis except one. Which was NOT part of Wegener's evidence?
stripes of reverse magnetism on either side of oceanic rides
Cirques often contain small lakes called ________.
tarns
Most of the erosion that took place during the "Dust Bowl" years of the 1930s in the Great Plains of North America was the result of which of the following processes
wind
Which of the following is the least effective agent of erosion?
wind
Where is the focal point of a glacier's growth?
in a cirque
In the early part of the twentieth century, ________ argued forcefully for the idea of continental drift.
Alfred Wegener
What is the desert land form shown in Figure 1? (Expand the window if you can't see the whole picture.)
An aluvial fan
How do glaciers fit into the hydrologic cycle, and what roles do they play in the rock cycle? PLEASE SELECT ALL THAT APPLY.
-Glaciers fit into the hydrologic cycle when precipitation that falls at high elevations does not immediately make its way toward the sea. Instead, it may become part of a glacier. Ultimately, the glacial ice will melt into water, which will continue on its path to the sea. -Glaciers play a role in the rock cycle by being dynamic erosional agents that accumulate, transport, and deposit sediment.
Why is wind erosion relatively more effective in arid regions than in humid areas? PLEASE SELECT ALL THAT APPLY.
-Moisture in humid areas binds particles together, which inhibits wind erosion. -Vegetation in humid areas anchors down the soil, which inhibits wind erosion. Submit
In general, where do earthquakes AND volcanic eruptions occur?
-divergent plate boundaries -convergent plate boundaries
Which of the below are depositional features created by glaciers? PLEASE SELECT ALL THAT APPLY.
-kames -drumlins -eskers -outwash plains
What do we call the isolated pinnacle of bedrock shown in Figure 5?
An inselberg
What do we call the gently sloping apron of sediment seen on the far side of the valley in Figure 3? It formed as alluvial fans merged.
A bajada
How does a medial moraine form?
A medial moraine is the result from the merging of two glaciers, causing their lateral moraines combining to form a medial moraine.
What do we call this flat area which is created when a desert lake dries out like the one in Figure 2?
A playa
What do we call a shallow, often temporary body of water in a desert basin like the one in Figure 4?
A playa lake
The terminus of a glacier will advance when which of the following conditions is met?
Accumulation of snow is greater than wastage
What are two differences between oceanic crust and continental crust?
The continental crust is thicker and less dense than oceanic crust.
Cross beds are a preserved record of what?
The deposition of sand on the leeward side of a dune.
Relate the glacial budget to the two zones of a glacier.
The glacial budget is the balance or lack of balance between the gain of snow in the zone of accumulation and the loss of ice in the zone of wastage.
Why is it difficult to reconstruct the glacial episodes of the Pleistocene Ice Age from the glacial record on land?
The glacial record on land is punctuated by many erosional gaps.
Working in a mountain valley that contains an alpine glacier, you discover a series of end moraines in the valley. As you move up toward the glacier, what conclusions can you expect to make about the moraines?
The moraines get younger as you get closer to the glacier.
During the Cold War, a B-52 bomber accidentally dropped an unarmed nuclear device on the Greenland Ice Sheet. Upon returning to the drop zone many years later, the device had gone missing. As a glaciologist on the project, where should you look for the missing device?
To find it you should go downslope from the drop zone, in the direction of ice flow.
Why are volcanoes NOT found at transform boundaries?
Transform boundaries do not cause changes to the pressure, temperature, or composition of the mantle.
What is the best way to describe the shape of a glacial valley?
U-shaped
In the desert environment, how are ventifacts created?
Ventifacts are produced on the surface of a rock by the continued impact of very small particles carried by the wind
Which of the following statements about deserts is true?
Water is the most significant agent of erosion in deserts.
Why do desert dunes migrate?
Wind erodes material on the windward side of the dune and deposits it on the leeward side of the dune. Submit
Playa
a dry, flat lake bed
Alluvial fan
a fan-shaped deposit formed when a stream's slope is abruptly reduced
What is the name used for random boulders left behind by a glacier?
erratics
A sinuous ridge composed of sand and gravel is a(n) ________; it is a deposit made by streams flowing in tunnels within or beneath glacial ice.
esker
When a glacial trough is "drowned" by the sea, the result is a(n) ________.
fiord
What is the name used for steep-sided inlets of the sea created when a glacial valley was flooded as sea level rose?
fjord
Identify the alpine glacial features indicated by the letter E in the above block diagram.
glacial trough
What do we call this "U-shaped valley which was created by an alpine glacier?
glacial trough
Identify the alpine glacial features indicated by the letter D in the above block diagram.
hanging valley
Identify the alpine glacial features indicated by the letter B in the above block diagram.
horn
What glacial feature is circled in Figure 2?
horn
What is the name used for pyramid-like peaks sculpted by valley glaciers?
horns
