In 1806, Meriwether Lewis and William Clark named a river on the south side of the Columbia River gorge the “Quicksand River.” Their description of a wide, shallow river with a bed “formed entirely of quicksand,” bears little resemblance to the narrow, moderately deep river we call today the Sandy River. What happened? The answer lay 50 miles away at Mount Hood. An eruption in the 1790's caused a tremendous amount of volcanic rock and sand to enter the Sandy River drainage. That sediment was still being flushed downstream when Lewis and Clark saw and named the river. Since 1806, the river has removed the excess sediment from its channel. The Toutle River in southwest Washington was similarly affected by the 1980 eruptions of Mount St. Helens. A sediment-retention dam was built in the late 1980's to trap sediment and ease flooding in the lower Toutle River below the dam.

pass4sure JN0-570
pass4sure 1z0-046
pass4sure 1z0-040
pass4sure 1Y0-259