Coastal Erosion and the Formation of Marine Terraces,
three animations

Erosion of beach cliffs by Waves.
These two movies illustrate the effects on beaches and beach cliffs caused by small waves and by large waves, inspired by the movie "Beach, River of Sand".

Suggested Narration:
During fair weather, ocean waves tend to be small. They use up their energy moving the beach sand around. The sand is our great friend; it acts as a buffer, protecting the coastline.

The large waves that occur during storms often stir up the sand and drop it into the quieter waters offshore, forming an offshore sand bar and leaving a smooth bare-rock beach terrace. When this happens, all the energy of the waves is concentrated on the beach cliffs, eroding them away and widening the wave-cut terrace.

To view each movie, click on its image.

Download: Wave Erosion Movies (7 MB)

Created by Tanya Atwater using Photoshop and Morph.

Formation and uplift of a set of marine terraces.
This movie illustrates how the combination of sea level fluctuations, wave erosion, and land uplift can result in the formation of a "staircase" of marine terraces.

Suggested Narration:
During the ice ages, sea level was falling and rising each time the great ice sheets formed on the continents then melted off again.

Movie zooms in closer.   Whenever sea level stood still with respect to the land, the waves cut a terrace into the edge of the land.

Movie zooms in closer.   Many parts of the California coast are being uplifted by tectonic forces. When this is the case, older terraces are uplifted so that each new still-stand cuts a new terrace, which in turn is uplifted. The result is a staircase of terraces.

To view this movie, click on the images.

Download: Marine Terraces Movie (11 MB)

Created by Tanya Atwater, Carrie Glavitch, and Erich Meyr using Photoshop, Morph, and Flash.

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