Earth Science Lecture Exam 2

Examine the diagram of the glacier movement experiment again. Can you determine how fast the center of the glacier was moving per day?

0.4 meter per day

What was the average yearly rate of ice advance in the center of the glacier?

115 meters per year

What is the natural angle of repose for sand?

34 degrees

If the data was collected over an 8-year time period, what was the average rate at which the ice advanced along the sides of the glacier in meters per year?

40 meters per year

Why is wind less effective than moving water at picking up and moving materials?

Air is less dense than water.

What is the relationship between the mantle and the asthenosphere?

All of the asthenosphere is contained within a larger layer called the mantle

What is the relationship between the crust and the lithosphere?

All of the crust is contained within a larger layer called the lithosphere.

________ are erosional features produced by valley/alpine glaciers.

Cirques

What are crevasses, and where do they form?

Crevasses are cracks that form in the zone of fracture at the top of the glacier. They form when tension is created as a result of the glacier moving over irregular terrain.

What is the relationship between water currents and cross beds?

Cross beds sit at an angle to current direction.

How does the rate of rock weathering in dry climates compare with the rate in humid regions?

Dry climates have much lower rates of chemical weathering and mechanical weathering than humid climates.

Which of the following is true about sand dunes?

Dunes move over time.

Which of the following statements characterizes ephemeral streams?

Ephemeral streams flow only at certain times of the year.

Under what conditions will the front of a glacier remain stationary?

Glacial fronts remain stationary when melting and snow accumulation are equal.

Glacial ice sheets are the largest of the types of glaciers and currently cover ________.

Greenland and Antarctica

How does an end moraine form?

Pieces of rock are transported to the front of a glacier as ice within the glacier moves.

What does saltating mean?

Sand grains are lifted by the wind, leap a short distance, and then fall back to the ground.

How do glaciers acquire their load of sediment?

Sediments and rocks are plucked off the ground surface at the base and sides of the glacier.

What is the relationship between the mantle and the lithosphere?

Some of the mantle is contained within a smaller layer called the lithosphere.

Can you identify the best reason why the rate of ice movement at the center of the glacier was larger than the rate of ice movement along its sides?

The center of the glacier is not in contact with the valley walls, and the edge of the glacier is.

What can you conclude about how this landscape has changed during that time period?

The glacier retreated greatly between 1935 and 2013.

An ice skater's blade pushes down onto the ice very hard, creating water as a result of the pressure from the weight of the skater. How is her skate acting like a glacier?

The weight of the ice in the top part of the glacier melts some of the ice at the bottom of the glacier, allowing for of plastic flow.

Which one of the following is not true of glaciers?

They exist only in the Northern Hemisphere.

Which of the following features is not created by glacial erosion?

V-shaped valleys

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.

What is the most important erosional agent in deserts?

Water

Why do desert dunes migrate?

Wind erodes material on the back side of the dune and deposits it on the front side of the dune.

Select the statements that are true about wind erosion.

Wind is most effective as an erosional agent in dry places An important erosion-related role of wind in a desert is abrasion of rock surfaces. Sediment deposited by wind in deserts can mostly be found in the form of sand dunes and loess deposits.

Will plucking occur if a glacier is NOT advancing?

Yes, because glacial ice is still moving inside the glacier even if the glacier's front is not advancing.

What is convection?

a cycle of moving material formed by the rise of less-dense material and the sinking of denser material

What is an end moraine?

a ridge of debris deposited at the end of a glacier

What surface feature would you expect to form if both a hot spot and a tectonic plate are stationary?

a single volcano

Which one of the following applies to a valley glacier that lengthens (extends the position of its terminus downslope over a period of many years?

accumulation exceeds wastage

What is a playa commonly occupied by?

an ephemeral lake

Crevasses (deep fractures or cracks) form in glaciers because ________.

as the glacier moves over irregular topography, the brittle upper layer or zone of fracture is subject to tension and cracks above the ductile layer

A cirque represents an erosional feature formed ________.

at the head of a glacier

Inselbergs are ________.

bedrock hills in a highly eroded desert landscape

Bajadas develop from ________.

coalescence of alluvial fans

What is the name used for cracks in the upper portion of a glacier?

crevasses

Which feature is labeled W in the diagram and shown in photograph B?

drumlin

Arêtes, horns, and U-shaped valleys are ________ features of ________ glaciers.

erosional; alpine

What is the name used for random boulders left behind by a glacier?

erratics

A(n) ________ is a deposit created by a former meltwater channel or tunnel in glacial ice that was filled with sand and gravel.

esker

Which feature is labeled Y in the diagram and shown in photograph A?

esker

What is the name used for steep-sided inlets of the sea created when a glacial valley was flooded as sea level rose?

fjord

What accounts for most tectonic plate motion?

forces at subduction zones

Fiords ________.

glacier-cut valleys that flooded as sea level rose in post-glacial times

The force of _______ allows particles to slide down the _____ slope of a dune as it moves.

gravity; leeward

Which one of the following is an evaporite mineral?

gypsum

A(n) ________ is likely to host a waterfall or steep rapids today.

hanging valley

What is the name used for pyramid-like peaks sculpted by valley glaciers?

horns

Glaciers are part of two of Earth's basic cycles: the ____________ cycle and the ____________ cycle.

hydrologic; rock

As an erosional agent, running water in arid regions is ________.

important because there is relatively little vegetation to anchor the sediment

Where do glaciers form?

in places where more snow falls in the winter than melts away in the summer

What are cross beds?

inclined layers in sediment or sedimentary rocks that reveal the direction of wave or wind transport

A playa is a(n) ________.

intermittent lake on the floor of a desert valley

A ________ lake forms when a block of ice is buried in drift and subsequently melts, creating a pit.

kettle

Which feature is labeled T in the diagram and shown in photograph E?

kettle lake

The __________ of a dune is characterized by a decrease in energy and sand avalanches, which occur due to oversteepening.

leeward side

Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern.

loess

The term drift ________.

means any sediments of glacial origin

Which of the following dune types would you expect to exhibit an arced shape that opens in the upwind direction, but where the slip face occurs on the downwind side of the dune?

parabolic

Which of the following is a lake that forms in a cirque?

tarn

Abrasion and plucking generally involve what part of a glacier?

the bottom or base

What is the snowline?

the elevation above which snow persists throughout the year

What do cross beds represent?

the moving front of a ripple or dune

What is the zone of wastage?

the part of a glacier where snow melting exceeds snow accumulation

What is dust?

the particles carried in suspension by wind

If the glacial budget is balanced (accumulation equals wastage), then ________.

the terminus of the glacier is stationary

Moraines are glacial deposits composed of ________.

till

What surface feature provides evidence for the location of hot spots?

volcanoes within tectonic plates

The loess deposited in many parts of the Midwest ________.

was once glacial outwash deposits

When will a hot spot volcano become extinct?

when the volcano is carried away from the hot spot by the tectonic plate

Glacial sediments or tills are characterized by ________.

wide variations in sizes of clasts

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

The force of the _____ pushes particles up the _______ slope of the dune as it moves.

wind; windward

Which of the following statements about deserts is true?

Water is the most significant agent of erosion in deserts.

Fan-shaped cones deposited at the mouth of a canyon in a desert are known as _____________.

alluvial fans

Which glacier deposit are drumlins mainly composed of?

till

Which of the following terms best describes long, sinuous bed forms that develop perpendicular to the prevailing wind direction in desert environments?

transverse dunes

Till is ________ glacial sediment.

unsorted

Which of the following is considered to be the most likely cause of the Quaternary Ice ages?

variations in the earth's orbit (Milankovitch cycles)

Milankovitch cycles refer to ________.

variations in the earth's orbit about the sun and precession of the earth's axis

. Sediment carried by the wind will drop to the ground when the wind's _______ decreases.

velocity

What is the relationship between temperature and density?

In general, warmer materials are less dense, and colder materials are denser.

What is cross bedding?

Layers deposited on a dune slip face that are inclined in the direction of wind transport.

What condition is most necessary to build a glacier?

More snow must fall in the winter than melts in the summer.

How do pieces of rock move under the influence of wind?

rolling, sliding, bouncing, suspension

What is the term for the rolling and bouncing of sand grains during transport?

saltation

Wind bounces and rolls sand along the ground, a process called ______

saltation

The North Pole is covered by ________.

sea ice

Most of an iceberg is underwater but the top of the iceberg sticks out because ________.

seawater is more dense than ice so ice floats in water

Ice sheets can be up ________.

several kilometers thick

What property of a piece of material will most directly determine how it is carried by wind?

size

At the base of a glacier, the ice moves by ________.

sliding and ductile flow

Which terms best describe the movement of a glacier?

slip plastic flow

Cross-bedded sandstone shows inclined beds in a downward direction. What part of the ancient dune do these features represent?

slip face

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.

Why are ice sheets primarily found in these regions? ( Greenland and Antarctica)

They are the coldest regions of the globe.

Where are glaciers found today, and what percentage of the Earth's surface do they cover?

Today, glaciers are generally found near Earth's poles and in high mountains. They cover nearly 10 percent of Earth's land surface.