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Mystery of the Megaflood
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Viewing Ideas
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Before Watching
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.
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
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?
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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