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Mystery of the Megaflood

Program Overview

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Flood NOVA presents the story of the greatest flood ever found in the geologic record and the geologist who went against prevailing theories to explain that the flood had occurred.

The program:

  • reviews geologist J Harlen Bretz's radical theory—first proposed in 1923—that a massive flood formed some of the Pacific Northwest's unusual geologic features.

  • presents the evidence collected by Bretz during his research, including the existence of the Channeled Scabland and the dry waterfalls, potholes, and erratics within the scablands.

  • explains that, at the time, most scientists believed the Northwest's geological features were created through gradual erosive processes; the scientists followed the theory of uniformitarianism, which ruled out sudden catastrophic creations of landscapes.

  • recounts the difficulty faced by Bretz as he worked to convince the scientific community of his theory.

  • reports the key role of Joseph Thomas Pardee, the geologist who found evidence for an enormous body of glacial meltwater that could have provided the flood's source of water.

  • describes how Pardee theorized that a lobe of the Cordilleran ice sheet dammed the Clark Fork River, forming an ice barrier that eventually walled off a lake described in size as "an inland sea."

  • recreates what might have happened when the lake's water eventually breached the ice dam, allowing Glacial Lake Missoula to flood westward.

  • reveals evidence indicating that the flood Bretz theorized may have been only one of many that repeatedly swept through the region.

Taping Rights: Can be used up to one year after the program is taped off the air.

Teacher's Guide
Mystery of the Megaflood
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