Hawaiian Coastal Cliffs

Resource for Grades 6-12

WNET: Nature
Hawaiian Coastal Cliffs

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Video

Running Time: 1m 54s
Size: 5.3 MB

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Source: Nature: "Violent Hawaii"

Learn more about the Nature film "Violent Hawaii."

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WNET

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WNET

Collection Credits

Collection Funded by:

Corporation for Public Broadcasting SC Johnson Canon

Major corporate support for the Nature collection was provided by Canon U.S.A. and SC Johnson. Additional support was provided by the Corporation for Public Broadcasting and the nation’s public television stations.


The events that created the majestic cliffs that border some of Hawaii's islands have long puzzled geologists. It was not until the mapping of the surrounding sea floor did scientists discover that catastrophic landslides produced the islands' sheer coastal cliffs. Learn more about the formation of Hawaiian coastal cliffs in this video segment from Nature.

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Transcript (Document)

open Background Essay

The earth’s landscape is naturally shaped by the forces of weathering and erosion. Weathering refers to the breakdown of rocks at or near the surface of the earth, either by chemical processes (e.g. limestone being dissolved by water) or physical processes (e.g. rocks cracking because of temperature extremes). The movement of weathered rock fragments-also called sediment-by forces including wind, water or gravity is called erosion. Human activity may both accelerate erosion (for example by removing vegetation which stabilizes soil), or prevent it (through reinforcement of erosion-prone areas like beaches, riverbanks and hillsides).


open Discussion Questions

  • Why couldn’t these cliffs have been created by wave erosion?
  • What geologic feature offers clues that the cliffs were been formed by massive landslides?
  • What might have caused the landslides?

open Transcript

The Hawaiian landscape has undergone cataclysmic changes many times in the past.

Some of the islands are bordered by towering cliffs.

Far below, just offshore, lie vast deposits of rubble. They provide clues to how these sheer cliffs were formed.

Walter Dudley is a geologist at the University of Hawaii.

Dudley: These enormous majestic cliffs for years have puzzled geologists, by their sheer size. The normal rates of marine erosion just couldn’t create these cliffs in the time that was available. And it wasn’t until the sea floor was mapped around it we discovered they weren’t produced merely by marine erosion but by enormous landslides, where whole chunks of the island fell off into the Pacific Ocean.

Evidence of these giant slides can be seen all around the islands. Scientists have identified at least 17 underwater rubble zones, covering thousands of square miles of seafloor.

Dudley: For me to be able to stand at the top of these sheer cliffs, and realize that in one catastrophic event much of that coastline had fallen down and slid off into the Pacific Ocean … awesome feeling… one is just amazed by the power of Mother Nature.

The events that left behind cliffs like these were no run-of-the-mill rockslides.

Dudley: The Hawaiian islands and every other island in the pacific has been sculpted by the force of these landslides. We’re talking about an incredibly large volume of material… thousands of cubic kilometers of material, all at once, just like these masses behind me… sliding off into the Pacific Ocean…


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