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Mystery of the Megaflood
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Viewing Ideas
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Before Watching
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Have students locate Washington, Oregon, Idaho, and Montana on a
U.S. map that displays landforms. What do they notice about the
geological features of the four states? Have students follow the
valley systems known as drainages. Do they link together? Do
they lead in a particular direction? Then have students locate
Missoula and the west flank of the Rocky Mountains and trace the
drainages of this area.
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Glaciers are often referred to as "rivers of ice." Ask students
what they know about glaciers. Have students ever seen a
glacier? In which regions of the world do students think they
would be located? Where in the United States? How are they
formed? Define glaciers for students and review some facts about
them (see
Background
for more information).
After Watching
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J Harlen Bretz's theories were at first dismissed by his peers.
Ask students to cite other scientists whose ideas were initially
rejected. What were the obstacles that those scientists faced?
How do they compare to the obstacles Bretz faced?
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To help students understand more about Earth's ice ages, have
them create a time line that includes the ice ages that occurred
during 1) the late Proterozoic (between about 800 and 600
million years ago), 2) the Pennsylvanian and Permian (between
about 350 and 250 million years ago), and 3) the late Tertiary
and Quaternary periods of the Cenozoic era (the past 4 million
years). To give them additional context, have students include
the age of dinosaurs and the ascent of humans on their time
lines.
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