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Flooding

Floods can cause tremendous damage, that people attempt to mitigate; that mitigation also has consequences.

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Down with Dogma-Uniformitarianism

Down with Dogma-Uniformitarianism

  

Credit: Dr. Julian Goldsmith
Source: http://en.wikipedia.org/wiki/File:J_Harlen_Bretz.jpg
License: CC BY-NC 3.0

Like Alfred Wegener with continental drift, J. Harlen Bretz had an outrageous hypothesis. He said that enormous ancient floods had ravaged the Pacific Northwest. Like Alfred Wegener, he was right.

What Created These Features?

Credit: USGS
Source: http://en.wikipedia.org/wiki/File:Map_missoula_floods.gif
License: CC BY-NC 3.0

Missoula Floods - (blue) Cordilleran Ice Sheet, (yellow) maximum extent of Glacial Lake Missoula in the east and Glacial Lake Columbia in the west, (orange) areas swept by Missoula and Columbia floods [Figure2]

  • In the early 20th century, uniformitarianism reigned in geology.
  • J. Harlen Bretz was a field geologist studying the Columbia River Plateau.
  • Bretz saw features he couldn’t explain with processes that people had witnessed.
  • Bretz said the channeled scablands (NOVA #9) were caused by massive flooding on an unimaginable scale.
  • His colleague, JT Pardee, found evidence of a giant ancient glacial lake.
  • Unlike Wegener, Bretz’s idea was accepted before his death.

Can You Apply It?

With the links below, learn more about the Missoula Floods. Then answer the following questions.

  1. Why did Glacial Lake Missoula drain so rapidly?
  2. What geological evidence is there for the existence of Lake Missoula?
  3. Why did other geologists think that the giant wavy landforms (#4) could not be ripple marks?
  4. Why did J. Harlen Bretz name the features near Grand Coulee the Channeled Scablands?
  5. Giant boulders in the Willamette Valley (#14) could have been deposited by a glacier. They could have been brought in by icebergs in a flood. How could you figure out how the boulders got there?
  6. Scientists still accept uniformitarianism. How can they accept it and catastrophism (the idea that catastrophic events do sometimes occur)?

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Image Attributions

  1. [1]^ Credit: Dr. Julian Goldsmith; Source: http://en.wikipedia.org/wiki/File:J_Harlen_Bretz.jpg; License: CC BY-NC 3.0
  2. [2]^ Credit: USGS; Source: http://en.wikipedia.org/wiki/File:Map_missoula_floods.gif; License: CC BY-NC 3.0

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