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Geologist
Task
Contribute to the group presentation of how glaciers shaped the Midwest and Northeast United
States. Take advantage of all the information in the geoscenario to successfully present your story and
the supporting evidence. You will be responsible for presenting information that answers the focus
questions in the box below (and on the Team Questions notebook sheet) for your team’s final product.
Questions for the Geologist
• What geologic features in this region were formed by glaciers?
• What is the geologic story of how they were formed?
Information
Over a period of 10,000 years (100,000–110,000
years ago), the temperature dropped about 17ºC
(63ºF), and the most recent Glacial Period began
(evidence from oxygen ratios and foraminifera
data). Around 20,000–35,000 years ago, the
Laurentide (or Wisconsin) Ice Sheet covered most
of Canada and a large portion of the northern
United States.
Events
25–20 tya: Glaciers advancing from the
Laurentide Ice Sheet carve out the Great Lake
basins.
21–18 tya: Terminal moraines deposit at the
southern edge of the glaciers in Northeast and
Midwest United States.
18 tya: Oldest seashells are found on Long
Island and Cape Cod.
11 tya: Glaciers retreat to just north of the
St. Lawrence River.
11 tya: Water flows out of the St. Lawrence
River. Water levels in Lake Ontario and Lake
Erie suddenly drop to about the level they are
today.
This picture shows a glacier pushing poorly sorted glacial till in front of it. The glaical till
forms a moraine.
Vocabulary
erratic boulders out-of-place boulders
composed of rock that is different from the
bedrock or other area rock.
glacial till the poorly sorted earth materials that
are carried and deposited by glaciers
moraine a mound of glacial till that is deposited
around at the edges of an advancing glacier
terminal moraine a mound of glacial till that is
deposited at the front end of a glacier
FOSS Earth History Course National Trials
© The Regents of the University of California
Can be duplicated for classroom or workshop use.
This picture shows glacial till being carried along by the glacier as the glacier moves
down the valley. As the glacier melts (toward the bottom of the picture), the glacial till is
deposited and forms moraines along the sides and in the middle of the glacier.
Geoscenarios: Great Lakes and Glaciers
Day 2, Resources
Page 1 of 8
St. Lawrence River
St. Lawrence River
The maps above show the retreat of the Laurentide (or Wisconsin) Ice Sheet. 14,000 years ago, the meltwater level in the Great Lake basins was much higher than it is today.
A glacier moved over this bedrock. Rocks embedded in the glacier dug these grooves, or
striations, in the bedrock. The grooves show which way the glacier was moving.
Things to Think About
Here are some things to think about that should
be part of your story of this region. Discuss the
following questions with your group:
This is a diagram of a rock column from a Great Lakes basin. The top layer is glacial till
(a few thousand years old) directly on top of Silurian rock, which is over 400 million
years old.
• Why didn’t the meltwater flow out the
St. Lawrence River 14,000 years ago, as it
does today?
• Look at the rock column. What happened
to the rock in the Great Lakes basin that
was younger than 400 million years? What
evidence do you have for your answer?
Describe the process.
FOSS Earth History Course National Trials
© The Regents of the University of California
Can be duplicated for classroom or workshop use.
Geoscenarios: Great Lakes and Glaciers
Day 2, Resources
Page 2 of 8
Glaciologist
Task
Share and explain the information you have about how glaciers form, move, advance, and recede. Also
explain how glaciers store data about temperature, snowfall, atmospheric gases, and volcanic eruptions
from thousands of years ago. Take advantage of all the information in the geoscenario to successfully
present your story and the supporting evidence. You will be responsible for presenting information
that answers the focus questions in the box below (and on the Team Question notebook sheet) for
your team’s final product.
Questions for the Glaciologist
• How do glaciers form, advance, and retreat?
• What information do glaciers provide about past environments?
Information
Glaciers store about 69% of the world’s fresh
water. Almost 10% of the world’s land mass is
currently covered with glaciers, mostly in places
such as Greenland and Antarctica.
Glacier Formation
Glaciers can form when more snow falls in the
winter than melts during the summer. Snow
accumulates and stays year-round at high altitudes
and high latitudes. After enough layers of snow
accumulate, there is so much weight pushing
down on the lower layers of snow that they
are transformed into extremely dense layers of
glacial ice. If it is in a mountain valley, gravity
slowly pulls the dense, massive ice toward lower
elevations. If it is on flat land, the weight of the
ice where it is the thickest will cause the ice on
the bottom to flow outward.
Water from glaciers is constantly melting and
refreezing. The water runs into cracks in the
bedrock and refreezes and expands, causing pieces
of the rock to break loose. The rocks, boulders,
and other earth materials that have frozen in the
ice become part of the glacier and are carried
along with the glacier as it moves.
Glaciers are always moving forward. A receding
glacier is not moving backward; it is simply
melting faster than it is moving forward. A
glacier that is building and moving forward faster
than it is melting is called an advancing glacier.
Other Interesting Facts
• When the climate warmed and the glaciers
began to melt, they produced millions of cubic
kilometers of very cold meltwater.
• Moraines from retreating glaciers formed dams
that kept the meltwater from flowing south.
• Towering, retreating glaciers formed ice dams
that kept the meltwater from flowing north.
FOSS Earth History Course National Trials
© The Regents of the University of California
Can be duplicated for classroom or workshop use.
The arrows show the flow
direction of the ice sheet. (How
would glaciologists know which
direction the glaciers moved?)
This map shows how much of North America the Laurentide (or Wisconsin) Ice Sheet
covered during the last glacial period.
A glaciologist in an ice cave in the Mendenhall Glacier in Alaska. Glacial ice is so dense
that only the blue-spectrum light can escape.
Geoscenarios: Great Lakes and Glaciers
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Page 3 of 8
• Snow that formed the estimated 70 million
cubic kilometers of Ice Age glaciers in North
America came from water that evaporated
from the ocean. This lowered the ocean level
worldwide by 130–150 meters.
Stories in the Ice
• Each year, snow forms a layer of ice in a glacier.
Ice cores can be drilled and removed from the
glacier in order to study the layers.
• Each layer of ice can be analyzed to determine
what was happening during the year that the
ice accumulated.
• Air bubbles trapped in the ice can hold
stories of air temperature and atmospheric
concentration of carbon dioxide, methane, and
sulfur dioxide from volcanic eruptions.
• Ice layers can also tell stories about atmospheric
concentrations of volcanic ash and pollen.
• Some ice cores from Antarctica provide a
record of over 400,000 years.
Events
Notice the layers within the glacier.
A glaciologist taking a sample
of an ice core.
20 tya: Glacial ice cores indicate the beginning
of a gradual warming trend.
15–11 tya: The Laurentide Ice Sheet retreats
from the northern United States.
710–160 ya (1300-1850): Glacial ice cores
show temperatures are 3–8°C (6–14°F) cooler
during the 550-year period in North America
and Europe.
200 ya (1815-1816): Volcanic ash and sulfur
dioxide gas bubbles are found in glaciers around
the globe.
160 ya (beginning of the Industrial Age):
Ice-core data shows that CO2 in the atmosphere
begins to increase.
60 ya (1950): Direct measurement of the CO2
level in the atmosphere shows a more rapid
increase, which continues to the present time.
Vocabulary
atmospheric CO2 concentration of carbon
dioxide gas in the atmosphere
ice cores cylinders of ice that have been drilled
out of a glacier
meltwater water from the melting glaciers
This picture shows boulders in a small pond of meltwater being carried along on top of a
glacier. When the glacier melts, the boulders will be deposited in an area far from where
they originated.
FOSS Earth History Course National Trials
© The Regents of the University of California
Can be duplicated for classroom or workshop use.
Geoscenarios: Great Lakes and Glaciers
Day 2, Resources
Page 4 of 8
Paleoclimatologist
Task
Share and explain the information about how you gather data about ancient climates and how you use
climate models to predict future climates. Take advantage of all the information in the geoscenario
to successfully present your story and the supporting evidence. You will be responsible for presenting
information that answers the focus questions in the box below (and on the Team Questions notebook
sheet) for your team’s final product.
Questions for the Paleoclimatologist
• What factors affect climate and climate change?
• How do scientists gather clues about past climates and use that information
to predict future climates?
Information
Factors Affecting Climate Change
(decrease) (increase) in global temperatures
 Greenhouse gases, such as CO2, absorb
sunlight and retain heat within the atmosphere,
causing an overall warming of the atmosphere.
This can have dramatic effects on global
weather patterns.
 Reflectivity of Earth’s surface—more clouds
and glaciers will reflect more solar energy back
into space and have a cooling effect.
 Variations in Earth’s tilt, wobble, and orbit
can cause gradual warming or cooling over
thousands of years.
 Clouds can either warm or cool Earth,
depending on their density and altitude.
 Urban environments create islands of heat
from industry, buildings, automobiles, and the
absorption of solar energy by dark-colored
surfaces.
 Reforestation and other habitat restorations
can create carbon sinks in which photosynthesis
converts CO2 to O2. Also, forests absorb
less surface heat compared to urban areas,
grasslands, or deserts.
Information from Ice Cores Taken from
Glaciers (work with the glaciologist)
• Volcanic ash and sulfur dioxide gas in a layer
indicates a volcanic eruption.
• Bubbles of gas in each ice layer can be analyzed
to determine the greenhouse and volcanic gases
that were in the atmosphere when the snow
was deposited.
• The thickness of the layer tells how much snow
fell that year.
• The ratio of different oxygen isotopes in the
ice indicate the air temperature when the snow
formed.
FOSS Earth History Course National Trials
© The Regents of the University of California
Can be duplicated for classroom or workshop use.
Storing the ice cores in Colorado.
A drilled hole.
The drill dome.
Additional Information
• Since the last ice age started (2 million years
ago), there have been about 18–20 glacial
periods (with ice sheets covering much of
North America) and warmer interglacial
periods in between.
• Since the burning of fossil fuels began in
earnest in the 1800s with the industrial
revolution, atmospheric CO2 levels have
increased more rapidly.
• Climate warming usually takes place slowly, at a
rate of 1–2ºC every thousand years. However,
it can take place over a few years.
• Earth has warmed 1ºC over the last 100 years. It is now warmer than it has been in the past
1,000 years.
• Climate cooling normally takes thousands of
years. However, catastrophic events, such as
volcanic eruptions and meteor strikes, can cause
major global changes in only a few years.
• Chemicals in fossilized coral reefs and
fossilized foraminifera shells indicate the water
temperature when the coral and forams were
living.
• Pollen grains found in seabed cores porvide a
record of when warm- or cold-weather plants
were growing in the area.
Geoscenarios: Great Lakes and Glaciers
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August 13, 1941
August 4, 1950
August 31, 2005
These three photographs taken from the same spot show how much Muir Glacier in Glacier Bay, Alaska, has thinned and retreated during the past 64 years. Most glaciers worldwide
have done the same thing. Even the glaciers in Glacier National Park in Montana will probably be gone by the year 2050.
Using Computers to Model and Predict
Climates
• Climatologists develop computer programs that
factor in dozens of variables to model climate.
• Data about paleoclimates are fed into
supercomputers to see if the computers can
accurately predict future climates.
• As more is learned about factors affecting
climates, the computer models have become
more accurate.
• Computer models indicate that the rapid
warming is due to the increased CO2 in the
atmosphere, which is caused by increased
burning of fossil fuels.
Events
2 mya: Seabed cores and foraminifera data
indicate a cooling trend and the start of the
Ice Age.
100 tya: Over a period of 10,000 years, the
temperature drops about 17ºC, and the most
recent glacial period begins (oxygen–isotope
ratios and forminifera data).
20 tya: Sea level is about 130–150 meters lower
than it is now. Most of the continental shelf is
exposed.
15 tya: Oxygen–isotope ratios in ice cores,
pollen grains in Mexico lakebed core, and ocean
cores all indicate the start of a gradual warming
trend, with the ice sheet retreating
1,100–800 ya (900-1300): Medieval warm
period, with global temperatures similar to today’s
temperatures.
710–160 ya (1300–1850): The Little Ice Age,
with temperatures 3–8ºC (6–14ºF) cooler.
200 ya (1816): The average temperature
per year in Europe and North America drops an
additional 0.4–0.8°C.
FOSS Earth History Course National Trials
© The Regents of the University of California
Can be duplicated for classroom or workshop use.
160 ya (about 1850, the beginning of the
industrial age): Ice-core data shows CO2 in the
atmosphere begins to increase.
60 ya (1950): Direct measurement of CO2 level
shows rapid increase, which continues to the
present time.
40 ya–present: The growing season (from the
first killing freeze in the fall to the last freeze in
the spring) lengthens by 3–4 weeks in temperate
regions.
Vocabulary
foraminifera microscopic marine animal with a
calcareous shell
glacial period a cold period when ice sheets
covered much of North America
greenhouse gas any gas in the atmosphere that
will trap reflected energy from the Sun
interglacial period warmer periods between
glacial periods when the ice sheets retreat
isotope atoms of the same element that have a
different atomic weight
seabed core a cylindrical sample of seabed that
is removed with a special drill
Geoscenarios: Great Lakes and Glaciers
Day 2, Resources
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Climate Policy Advisor
Task
Share and explain the information about how climate change has affected people in the past and how
it will likely affect people in the future. Take advantage of all the information in the geoscenario to
successfully present your story and the supporting evidence. You will be responsible for presenting
information that answers the focus questions in the box below (and on the Team Questions notebook
sheet) for your team’s final product.
Questions for the Climate Policy Advisor
• How have climate changes affected the environment and people in the past?
• How can this information help us plan for the future?
Information
Policy advisors work with people in various
agencies to develop plans to reduce the negative
effects of climate change. Policy advisors study
• historical data about how weather and climate
changes have affected people;
• climate data and predictions to determine how
best to serve the needs of people now and
prepare for future climate change.
Information about a Warming Climate
• The United State produces more greenhouse
gases than any other country on Earth.
• Computer-climate models indicate that the
increased greenhouse gases are creating a
warmer climate.
• Small changes in temperature cause significant
changes in weather patterns
• Increasing global temperatures are causing
- changes in precipitation patterns (drier or
wetter).
-sea level to rise 3 mm/yr because of water
expansion.
-the rate of rise of the sea level to speed up as
ice sheets in Greenland and Antarctica melt.
-warmer summer temperatures, which put
extra stress on people, other animals, food
crops, and other plants.
- a growing season that is 2–4 weeks longer than it was in 1970.
-more frequent severe storms (tornadoes, floods, hurricanes with storm surges, hail, high winds).
-storm surges to destroy coastal wetland habitats and flood low-lying coastal areas.
-the population size of many insects that carry
disease (for humans, plants, and animals, feed on crops, and trees) to increase.
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-tropical insectborne and waterborne diseases
(for humans and wildlife) to become more
widespread.
-dead trees; dry grass; more wind and
lightening; and hotter, dryer summers—all of which create extreme fire danger.
-animal and plant extinction, due to habitat loss from melting ice caps, dying forests, dying coral reefs, and spread of diseases.
-coral around the world to die from
warmer water and acidification. The
acidification also prevents plankton and
shellfish from forming shells and reduces
the survival rate of many young fish.
Future Planning Needs
Create public-awareness campaigns to inform
people of the climate changes that are already
taking place. These campaigns would also inform
people how to reduce activities that produce
greenhouse gases, such as
• implementing policies that encourage the use
of alternative-energy sources and conservation
of fossil fuels;
• planting more trees to take in and store CO2;
• encouraging the use of more energyefficient forms of transportation, building,
manufacturing, and food production.
Plan for more frequent severe weather, flooding,
and storm surges (in coastal areas) by
• building seawalls and levees and relocating
structures and roads.
During a hurricane, most damage and loss of life
is caused by the storm surge.
Geoscenarios: Great Lakes and Glaciers
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• changing building codes so that buildings will
withstand stronger storms.
• creating zoning laws so that future buildings
will not be built in areas that are likely to flood.
• establishing emergency procedures for
evacuation routes; rescue operations; and
community shelters for water, food, medical
supplies (to treat injuries and waterborne
illnesses), and other basic services).
Other considerations include
• planning for food storage and distribution, in
case of crop failures;
• implementing practices that reduce the severity
of wildfires;
• training medical personnel to be more
familiar with the diagnoses and treatment of
insectborne and tropical diseases and heatstroke.
Events
1,100–800 ya (900–1300): Norse voyagers
settle Greenland and North America.
710–160 ya (1300–1850) Little Ice Age: Several famines occur when crops do not survive.
Millions die from epidemics of the bubonic
plague, typhoid, and other diseases associated with
malnutrition.
630 ya (1380): Norse settlers abandon most of
Greenland. Crops and livestock freeze.
220 ya (1790–1815): Coal extraction and use of
coal increases from 6 to 16 million tons.
1816: a drop of only 0.4–0.8ºC in average
temperature causes a “year without a summer”
in the northern United States and Canada.
Livestock and wildlife starve or freeze, and there
Global Average Temperature 1900-2100
If the sea level rose 1.5 meters, the red areas would be flooded. Blue areas would flood if
the sea level rose 1.5–3.5 meters.
is no food to hunt. In the United States and
Canada, thousands of people starve.
1850: Burning coal to power factories and trains
begins to increase significantly. The carbondioxide level in the atmosphere also begins to rise.
1950: Fossil-fuel use begins to rise dramatically,
as does the CO2 in the atmosphere.
1995: Rapid expansion of manufacturing and
transportation in developing countries, such as
China and India, increases CO2 levels even faster.
2009: The Intergovernmental Panel on Climate
Change issues a report stating that the climate
change taking place is almost certainly being
caused by greenhouse gases. However, some
people still don’t believe that human activity can
cause the climate change.
Vocabulary
alternative energy usually a nonfossil-fuel form
of energy, such as wind, solar, geothermal, or
hydroelectric
insectborne disease a disease carried by an
insect (such as malaria, which is carried by a
mosquito)
policy an agreed-upon procedure for dealing
with a question or issue
storm surge high winds pushing on the
ocean’s surface, which push water inland causing
flooding. Most of the fatalities and destruction
during a hurricane occur during a storm surge.
waterborne disease a disease carred by an
organism that lives in the water
Scientists create computer models, using many variables (such as human fossil-fuel
use, cultural changes, price of oil or gasoline, car production, and alternative-energy
development) to try to predict how our behavior will impact future atmospheric CO2 levels.
This graph shows the predicted temperature increases, with various levels of CO2 increase.
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Can be duplicated for classroom or workshop use.
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