Download Chapter 3 Review Questions Knowledge 1. The Big Rock at Okotoks

Chapter 3 Review Questions
Knowledge
1. The Big Rock at Okotoks was carried from the Rocky Mountains by an advancing ice sheet
during the last glaciation.
2. The following diagram outlines the Cenozoic Era.
3. Ice flows like water under the influence of gravity’s pull, but at a much slower pace. Just like
water, ice causes erosion by carrying material along as it flows.
4. The Cypress Hills were Nunatak during the last ice age. This means that the height of the
plateau protected them from the grinding of the ice sheets that scoured lower areas. The ice
that eroded away many other rock formations flowed around the Cypress Hills.
5. The drainage of the Bearspaw Sea was caused by the uplift of the Rocky Mountains. The
increased height of that part of Alberta caused the Bearspaw Sea to drain to the southeast.
6. Glaciation occurs when continental ice sheets form on land masses near Earth’s polar regions
and then advance outward to cover other parts of the globe.
7. Before the Rocky Mountains had experienced repeated glaciations, they were much more
rounded with V-shaped valleys due to water erosion.
8. There was a cooling of Alberta’s climate during the Tertiary Period. A possible cause of this
cooling trend could be that North America was moving farther north due to plate tectonics.
9. Mammals and feathered dinosaurs became Alberta’s dominant organisms after the extinction
of the large dinosaurs.
10. Alberta was cooler than it had been in millions of years. It was a grassland home to large
grazing animals including rhinoceroses and elephant-like woolly mammoths.
11. Scientists can analyze layers of calcium carbonate left in ocean sediments from the last 65
million years. The ratios of oxygen-18 to oxygen-16 incorporated into the shells of
Foraminifera fossils in the layers are indicators of average temperature.
12. The climate in the Tertiary Period was cooling but was still warmer than it is today. There
were repeated glaciations during the Quaternary Period, at which time ice sheets advanced to
cover Alberta. At present, Earth is between glaciations.
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A continental ice sheet forms when there is an annual accumulation of snow on a land
mass. When the snow becomes thick enough, it is compacted into ice and begins to flow
outward in all directions. Modern examples of continental ice sheets exist in Greenland
and Antarctica.
A mountain glacier forms when snow accumulates year after year on a mountain.
Eventually, the snow compacts into ice and begins to flow down the mountain. Probably
the most famous glacier in Alberta is the Athabasca Glacier, but there are many other
examples.
14. The glacier-fed creek on the left has exposed an outcropping of rounded boulders, gravel,
and sand known as glacial till. Outwash from the glacier cuts the stream bed. This shows that
a glacier must have covered this area at one time. This photo on the right shows the
characteristics of mountain glacier landforms—U-shaped valleys with steep sides that end in
sharp ridges. If the optional extension activity titled “Naming Glacial Landforms” was done,
then students could also have named some specific features. The round bowls are cirques,
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the peaks are horns, the ridges are arêtes, and the green lakes are tarns. Moraines can also
be seen.
The ice core was drilled at Lake Vostok in Antarctica. It contained annual snowfall layers for
the past 420 000 years. Oxygen-18: oxygen-16 ratios were analyzed in each layer to
determine the temperature changes over that time period.
The Wisconsin Glaciation reached its maximum extent 18 000 years ago when the
Pleistocene Ice Sheet advanced to cover nearly all of Alberta. It melted approximately 10 000
years ago, ushering in the Holocene Epoch.
Scientists can determine the direction of ice-sheet movement by analyzing the shapes of
glacial landforms—such as drumlins—which literally point in the direction of ice-sheet flow.
They can also observe the direction of scratch marks, formed as fill was dragged over
bedrock.
The many continental glacial landforms, such as moraines, drumlins, eskers, kettle lakes,
kames, and outwash plains, do not extend south of Wisconsin in the east and northern
Montana in the west.
Mountain glaciers have given the Rockies a much more jagged appearance due to the
formation of mountain glacial landforms, such as horn peaks, cirques, and arêtes.
Glaciers aid basic needs by providing fresh, clean drinking water. Thirsty Edmontonians
obtain water from the North Saskatchewan River, which is fed by the Saskatchewan Glacier.
Thirsty Calgarians obtain water from the Bow River, which originates in the Bow Glacier.
The current global warming trend is resulting in more annual melting than annual snowfall.
Due to this, many mountain glaciers and ice sheets are shrinking.
Weather includes variables, such as temperature and precipitation, on a daily or even an
hourly basis. Climate is an average of these variables for a much longer period of time—at
least 30 years.
To increase the certainty in predictions about future climate changes, scientists are working
to understand how the global climate system operates. Scientists are also trying to improve
ways to record present conditions.
During Earth’s history, there have been about five major cold periods. Each period has lasted
millions of years and featured repeated glaciations. Earth is currently experiencing one of
these cold snaps. Luckily, people are enjoying a temporary warm period between glaciations.
Continents can drift to the polar regions where snow accumulates. Once ice sheets form, they
have a global cooling effect. When oceans change shape due to plate tectonics, oceancurrent patterns are changed, and these are significant determiners of climate.
Ice sheets are white. This means that they reflect all the colours of sunlight back out into
space, rather than absorbing them. This helps ice sheets stay frozen and keeps Earth cool.
When the three types of variations—shape of orbit, axial tilt, and axial wobble—are
combined, they closely correlate with the timing of the repeated glaciations during the
Pleistocene Period.
The Vostok ice core shows a strong correlation between the atmospheric carbon dioxide
concentration and the average temperature. Average temperature is determined by analyzing
oxygen-18: oxygen-16 ratios, while concentrations of carbon dioxide can be measured from
little bubbles of atmospheric gases trapped in annual ice layers.
People are mainly adding to the atmospheric carbon dioxide concentration by burning fossil
fuels. This increase in atmospheric carbon dioxide is believed to be enhancing the natural
greenhouse effect, causing an artificial increase in the average global temperature.
The enhanced greenhouse effect could cause a continued melting of the Greenland Ice Sheet
to the point that it slows down the North Atlantic Conveyor. This would cause a cooling of
northern places like Canada and, especially, northern Europe.
Applying Concepts
31. An inference that could be made from this evidence is that at some time it must have been
much warmer in the Arctic.
32. Glacial ice is produced over many years as snow accumulates and is packed down. Gravity
then acts on the ice to pull it down the slope.
33. Students will recall from their work in Chapter 1 that a plastic is a material with the
properties of a solid, but it can also flow under pressure. Glacial ice is said to have the
properties of a plastic because a glacier flows very slowly as gravity acts to pull the ice down
the slope.
34. The fresh water that flows from glaciers is used for drinking water, hydroelectric power,
irrigation, and recreation.
35. The brewing controversy is the validity in predicting and understanding climate change as
developed by computer modelling.
36. Although there are uncertainties in the ultimate cause of climate change, all indications point
to human influence as a contributing factor.
37. The identification of human influence as a contributing factor implies that action should be
taken to identify how people are causing climate change. Steps should then be taken to
reduce or eliminate the human impact.
38. Predictions about computer modelling cannot be 100% accurate.
39. Scientists use models to simulate the climate and then compare results to the data records.
40. Dr. Bush sees scientific knowledge changing as new evidence comes to light.
41. Japan’s Earth Simulator supercomputer is the leading climate-modelling technology.
Science 20 © 2006, Alberta Education