Geology SB chapter 14

Glacial Lake Bonneville was extensive during the Ice Age. It has since shrunk in size; what remains are the Bonneville salt flats and the Lake in Utah.

-Great -Salt

Which of the following control the Milankovitch cycles that influence global climate?

-Obliquity (varying tilt angles of the Earth) -Precession (the wobble of Earth's rotational axis) -Eccentricity (the varying shape of Earth's orbit)

Which are true of the ice in West Antarctica?

-The ice sheet carries massive amounts of ice toward the sea and ice shelves. -The ice shelves are losing large volumes of ice every year. -The base of the ice sheet is below sea level. -The central part is as thick as 3,500 m.

Look at the accompanying photograph. The dark gray material covering the sides and head of the glacier is ______.

rocky debris plucked from the bedrock as the glacier passed over it

The largest accumulations of ice are in glaciers we call ice . Glaciers that flow down valleys in mountainous regions are , cirque, or valley glaciers. When either of these two glacial types spread out in less confined topography, they are glaciers. (Use just one word for each answer.)

sheets alpine piedmont

The principle behind the saying "the present is the key to the past" can be applied to glaciers by ______.

studying the deposits of modern glaciers in order to understand the processes that formed ancient glacial deposits

The Channeled Scablands in eastern Washington were formed during the last ice age ______.

-when floodwater caused rapid and large-scale erosion -when ice dam failures created enormous floods

Match the type of glacier with its description. Instructions 1. Ice sheets 2. 3.

1. Choice, Large, regionally continuous masses of ice more than 50,000 km2 in area Large, regionally continuous masses of ice more than 50,000 km2 in area 2. Choice, Glaciers that begin in mountainous terrain and flow down valleys Glaciers that begin in mountainous terrain and flow down valleys 3. Choice, Broad glaciers that form when a more restricted glacier spreads out as it moves into less confined topography Broad glaciers that form when a more restricted glacier spreads out as it moves into less confined topography

If global sea levels rise, what could happen to West Antarctica?

More of the ice sheet could float and detach; collapsed parts would melt and raise sea level more.

Huge ice dams broke numerous times during the Ice Age to create enormous floods that carved the Channeled in Washington.

Scablands

Which of the following statements accurately compares the average relative length of glacial and interglacial periods over the past 2.5 to 3 million years?

Glacial periods last longer than interglacial periods.

How are till and tillite related?

Glacial sediment called till hardens into the rock called tillite.

What are the two names of the scratches and gouges created by sediments and rocks that glaciers carry at their bases?

Glacial striations Glacial grooves

The were created by the combined action of the Laurentide Ice Sheet carving the land surface, depositing moraines, leaving meltwater, directing drainage, and finally the land surface rebounding as the ice receded.

Great Lakes

In what ways do glaciers lose mass?

Ice breaking off the glacier Via sublimation Via glacial meltwater

All of these are large masses of ice. Choose those that are not technically glaciers.

Ice fields Sea ice

East and West Antarctica each have their own ice sheet and are separated by the Transantarctic .

Mountains

Which of the following best describes the amount of energy given off by the Sun and the composition of the atmosphere, both of which affect Earth's global climate?

Neither one is constant over time.

The ____ Epoch ended about 10,000 years ago with the most recent retreat of the expansive glaciers of the Ice Age.

Pleistocene

What is the name of the time period that started approximately 2 million years ago and ended about 10,000 years ago, and is also marked by a large number of glacial periods?

Pleistocene Epoch

What is till?

Sediment deposited directly by ice

Which of the following statements is true regarding the internal flow within an ice sheet that is retreating?

The ice within the ice sheet flows forward but the rate of forward flow is slower than the rate of melting at the front.

Based on the image and your knowledge of the relationship between melting ice and sea level, what is true?

The melting of block A will raise the level of water in the tub.

How can a terminal moraine be distinguished from a recessional moraine?

The only difference between them is geographic. A terminal moraine is the forwardmost moraine created by glacial deposition.

When sunspot activity is at a low, it causes Earth's climate to ______.

cool by a tiny amount

During an ice age, when most glaciers and ice sheets are advancing, the time is a(n) ______ period, but when they are retreating, the time is a(n) ______ period.

glacial; interglacial

The deposition of sediment by glacial streams is ______ deposition.

glaciofluvial

The rocks that glaciers transport at their base scratch the underlying surface and create striations and deeper gouge marks that we call glacial .

grooves

The creation of large amounts of glacial ice during ice ages preferentially leaves behind ______ oxygen isotopes in seawater and enriches the ice with the ______ isotopes.

heavier; lighter

Glaciers in Asia currently exist ______.

in high latitudes

Glacial lakes, or , commonly form in a series we call paternoster lakes.

tarns

The rock shown in this image is called tillite. It formed from glacial sediment called

till

This is the (single) word we use to describe the unsorted and unstratified sediment deposited directly by ice.

till

As a continental glacier passes over the land, it tends to erode the topographic highs and deposits sediment in topographic lows. This results in land with a ______ relief than existed prior to the glaciation.

lower

aciation in Euro

was extensive during the Pleistocene is now limited to alpine glaciers that are receding

Geologists use all of the following except ______ to investigate the where and when of glaciations.

magnetic reversals

Sunspot activity has a ______ effect on Earth's climate.

measurable but small

Glaciofluvial deposits are associated with glacial .

meltwaters or outwash

This bit of bedrock sticking up out of the ice sheet in Antarctica is a(n)

nunatak

Continents move over geologic time and affect climate by both their latitudinal position and how they influence the flow of currents.

ocean

Rivers and streams flowing away from glaciers deposit ______.

outwash plains

In high-latitude locations where trees are short and leaning in random directions, ______ is most likely preventing the trees from developing a deep root structure.

permafrost

Northern Canada and Alaska are the only locations in North America where ______ exists in large continuous areas.

permafrost

The melting of continental glaciers in Antarctica would cause global sea levels to , and would effect coastal areas of the eastern US.

rise

Which of the following describe the role of ocean currents and continental positions on glaciations and global climate?

-Cold ocean currents may inhibit the growth of glaciers by putting less moisture into the atmosphere. -Upwelling ocean currents may bring cold water to the surface, helping to cool the land.

Select all that apply Identify effects of permafrost.

-Geometric patterns can develop at the surface. -it prevents or limits the growth of trees.

Match the feature with its description and how it may indicate the past presence of glaciers. Instructions - Erratic - Dropstone - Tillite - Polished and scratched bedrock

- Bedrock that has been smoothed and grooved; glacially carried sediment erodes away at the bedrock below. - A huge out-of-place block deposited on a landscape; glaciers transport huge rocks to places where such rock types are not present in the bedrock. - A larger stone that is deposited in otherwise fine-grained marine and lake sediment; floating icebergs dropped the stone. - Consolidated till; poorly sorted, glacially deposited sediment that has now become a sedimentary rock.

Match the activity to its climatic effect. Instructions - Decreased sunspot activity - Increased snow and ice cover on Earth - Release of CO2 and CH4 into atmosphere - Large volcanic eruptions

- Climate cools slightly. - Increased albedo makes a cooler climate. - More greenhouse gases tend to warm the planet. - Ash and dust block sunlight, resulting in cooling.

Match the name of the moraine with its description. Instructions - Lateral moraine - Medial moraine - Terminal moraine

- Forms along the sides of a glacier - Forms down the center of a glacier when two tributary glaciers meet - Forms at the farthest extent of a glacier advance

Match the names of lakes that existed in glacial times with the features that remain today. Instructions -Lake Bonneville -Lake Missoula

- Great Salt Lake; salt flats - Channeled Scablands

Match the Milankovitch cycle change with its description. Instructions - Maximum tilt angle of the Earth - Minimum tilt angle of the Earth - Precession - More eccentricity - Less eccentricity

- Increases the effects of the seasons; warmer summer temperatures melt more polar ice; cycles about every 40,000 years. - Decreases the effect of the seasons; cooler summers lead to an increase in glaciation; cycles about every 40,000 years. - Each cycle lasts about 23,000 years; this "wobble" may affect global climate. - Earth's orbit is slightly more elliptical; cycles last about 100,000 years. - Earth's orbit is slightly more circular; cycles last about 100,000 years.

Match the glacial features with their descriptions. Instructions - Eskers - Kettle lake - Glacial outwash - Recessional moraine - Till - Drumlins

- Long, sinuous ridges deposited by meltwater stream beneath a glacier as it retreats - Formed as a block of ice left behind by a glacier melts, leaving a depression that fills with water - River-carried sediment that may either be deposited near or distant to a retreating glacier - Forms as the front of a glacier melts back and stagnates for some period of time in one location, depositing a pile of sediment - The general name given to deposited glacial sediment - Streamlined hills formed as a moving glacier sculpts material into this shape

Match the term on the left to its definition regarding the relative location of transport of sediment by a glacier. Instructions - Englacially - Supraglacially - Subglacially

- Sediment is transported within the glacier. - Sediment is transported on top of the glacier. - Sediment is transported at the base of the glacier.

Match the erosional glacial landform with its description. - Aréte - Tarn - Hanging valley - U-shaped valley - Cirque

- This is a jagged ridge formed between two glaciers, as they eroded from both sides. - This is a small lake in a glacially scoured depression. - The side valley is higher than the main valley; created because larger glaciers scour deeper into bedrock than smaller, side valley glaciers. - Smoothing action of a glacier creates this large-scale feature. - A bowl-shaped depression is created as ice plucks pieces from the bedrock at the uppermost end of a mountain glacier.

Why does continental glaciation tend to smooth the surface of the land, causing the ground topography to have relatively low relief (minor height differences between lower and higher topographic locations) once the ice sheet melts?

-The ice sheets tend to deposit sediment in topographic lows. -The ice sheets round and erode any of the higher areas over which the ice flows.

Regarding the image, and based upon your knowledge of glaciers, which of the following are true?

-The zone of accumulation is higher in elevation than the zone of ablation. -As a glacier moves downhill, it loses more and more ice by melting and sublimation. -The equilibrium line sometimes is marked by a boundary between snow-covered ice upslope and bluish ice downslope.

Which of the following are true of how proportions of oxygen isotopes are changed over interglacial and glacial periods in seawater and glacial ice?

-When glaciers accumulate on land, more oxygen-16 is locked away in glacial ice and does not make it back into seawater. -When glaciers melt, oxygen-16-rich water is released back into seawater. -Oxygen-16 is preferentially evaporated out of seawater.

A positive feedback in a climatic sense would cause ______.

-a cooling climate to become even cooler -a warming climate to become even warmer

Compared to glacial periods, interglacials are marked by ______.

-lower ratios of oxygen-18 to oxygen-16 in seawater -lower ratios of oxygen-18 to oxygen-16 in the compositions of marine shells (less heavy isotopes)

Order the steps of glacier ice formation from snowflakes, beginning with the snowfall. (Place the first step at the top.)

1. snow falls as individual flakes 2. Snowflakes are pressed together air is forced out 3. snowflakes are compressed into irregular, dense spheres 4. Snow changed into interlocking crystals and has a bluish color 5.

Which axial tilt angle would most encourage the growth of glaciers?

22.5°

Which of these situations would cause a very full glass of lemonade to spill over?

A cube of ice is melted and added to the drink

Imagine you are in a recently glaciated region and you come upon a large pile of sediment. The rocks are many different sizes, many of them are angular, and you don't see any layering. Which of the following is the correct interpretation?

A glacier deposited the sediment.

What is permafrost?

A layer of soil that remains frozen year after year

What is a nunatak?

A small area of bedrock high enough to protrude through an ice sheet

Correctly identify the features indicated on the image. Instructions A- B- C- D-

A- Cirque B- Tarn C- Hanging valley D- Aréte

Match the locations on the image with descriptions of glaciers present there. Instructions A. B. C. D. E.

A. Choice, Antarctica: it is the largest ice mass on Earth and has mostly ice sheets with some valley glaciers. Antarctica: it is the largest ice mass on Earth and has mostly ice sheets with some valley glaciers. B. Andes (especially Patagonia): glaciers occupy high peaks, mostly in the southern part of the mountain range. C. Choice, North America: glaciers present mainly in the higher peaks in the west. North America: glaciers present mainly in the higher peaks in the west. D. Greenland: large ice sheets and smaller glaciers occupy 80% of this landmass. E. Choice, Tibetan Plateau and the Himalaya: glaciers cover many of the highest parts of this area. Tibetan Plateau and the Himalaya: glaciers cover many of the highest parts of this area.

A. Ice sheets B. Alpine glaciers C. Piedmont glaciers

A. Choice, Large, regionally continuous masses of ice more than 50,000 km2 in area Large, regionally continuous masses of ice more than 50,000 km2 in area B. Glaciers that begin in mountainous terrain and flow down valleys C. Broad glaciers that form when a more restricted glacier spreads out as it moves into less confined topography

Match the features on the image with their names. Instructions A. B. C. D. E.

A. Esker B. Kettle lake C. Drumlins D. Recessional moraine E. Terminal moraine

In North America, permafrost is located in ______.

Alaska northern Canada

What is the formational history of the Great Lakes?

Ancestral lakes formed 14,000 years ago between moraines and ice fronts, then drained at spillways. The modern lakes formed about 4,000 years ago.

What is glacial drift?

Any sediment transported by glaciers, icebergs, or meltwater

Correctly identify the different types of moraines shown in the picture. Instructions -B -A

B- Lateral moraine A- Medial moraine

True or false: The movement of a glacier in retreat means that all ice is moving backwards, e.g., in the opposite direction of glacial advance.

False

Which of the following correctly describes Antarctica?

It has two sides, East and West, each with its own ice sheet. The sides are separated by the Transantarctic Mountains.

What is the active layer of permafrost?

It is the uppermost layer that thaws during the warmer periods.

What is firn?

Small, irregular spheres of ice made from compressed snow

How are tarns and pasternoster lakes related?

Tarns that are connected by streams are referred to as pasternoster lakes.

Which of the following statements are true regarding the North America ice sheets 28,000 years ago?

The Cordilleran Ice Sheet covered western Canada but not much of Alaska. The Laurentide Ice Sheet was centered over Hudson Bay in northern Canada.

Between 28,000 and 11,000 years ago, which of the following occurred in North America?

The upper Mississippi River began to develop. Glacial ice retreated. The Great Lakes formed.

True or false: There were many glacial and interglacial periods over the past two million years.

True

The Antarctic Ice Sheet is the smaller of the two on the continent. Much of it's base is below sea level.

West

If we described a land as having kame and kettle topography, what would it look like? The land would have ______.

a bunch of scattered and rounded topographic highs and a bunch of scattered and rounded depressions

Not all large masses of ice are glaciers. A large accumulation of snow and ice that does not move is called ______. When large masses of ice form when the upper surface of the ocean freezes, that ice is called ______.

a snowfield; sea ice

Area A is the zone of ______, where snow and ice are added faster than they melt. Area B is the zone of ______, where ice melts faster than it is replenished.

accumulation; ablation

The uppermost layer of permafrost that thaws in the summer is called the layer.

active

How does the movement of ice sheets differ during glacial and interglacial periods? During glacial periods, ice sheets ______.

advance, but during interglacial periods, they retreat

Glacial ice forms ______.

as snowflakes are buried and compressed, eventually becoming crystalline ice

Sediments that are directly deposited by a glacier will ______.

be generally angular lack bedding

The top of a glacier moves in a ______ fashion; the middle of the glacier behaves ______.

brittle; plastically

Scientists are concerned that rising sea levels could ______ the West Antarctica ice sheet from the underlying bedrock, which would lead to more of the collapsed parts melting.

detach

Lower axial tilt angles ______ the growth of glaciers.

encourage

Calculations of the effect of melting the West Antarctic Ice Sheet on global sea level estimate a 6 m rise. Much of the East Coast of the United States is at high risk because of low elevations; the most vulnerable areas are barrier .

islands

Geologists study the chemistry and preserved in ocean fossils and sediments to better understand the timing of glaciations.

isotopes

A glacier will move faster if ______.

it's bottom surface has a thin film of water it moves over a smooth surface

Bumpy glacial terrain that is composed of numerous small, conical hills and small, round depressions (that are commonly filled with water) is called and topography.

kame kettle

A feedback is one in which a change in the system causes the system to continue to move in that same direction. Ice, for example, increases the surface albedo, and this tends to cool the climate even more, resulting in more ice cover and further cooling.

positive or +

The wobble in Earth's axis, its , causes the timing of the seasons between hemispheres to be reversed on a 23,000 year cycle.

precession

By studying the processes occurring in modern glaciers and the sediment that results from those processes, we can more fully understand ancient glaciations. We are applying the concept behind the saying "the ______ is the key to the ______."

present; past

When a glacier is stagnant in its lateral movement, it deposits a moraine at its toe; a moraine marks the farthest location the glacial reached.

recessional terminal

The precession of Earth's axis ______.

reverses the timing of the seasons by hemisphere