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Ribbon Cliff, near the Columbia River, produced a slide possibly as a result of the most intense earthquake to hit Washington State. The quake took place 14, December 1872 and was rated at nearly 7.3 on the Richter Scale. Debris from the slide was reported to have blocked the flow of the Columbia river creating a lake behind a rock dam. The black specks in the granite are biotite mica, the lighter material is feldspar and quartz. |
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| Ribbon Cliff, North of Entiat, Washington on the Chelan Highway. The bands are dark veins of igneous material cutting through the mountain. The image below shows the Columbia River just below and across the highway from the cliff. The large rock debris in the river is a remnant of the slide that occurred here in 1872. Reports said that these rocks and other debris blocked the river at this point forming a lake behind the rock dam for quite some distance up the Columbia. |
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