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The Grand Canyon. What is it?. On the Colorado Plateau, in the northwest of Arizona, USA Carved by the Colorado River One of the 7 Wonders of the World. How big is it?. 277 miles (446 km) long 18 miles (29 km) wide Up to 6,000 feet (1,800 m) deep. How big is it?.
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What is it? • On the Colorado Plateau, in the northwest of Arizona, USA • Carved by the Colorado River • One of the 7 Wonders of the World
How big is it? • 277 miles (446 km) long • 18 miles (29 km) wide • Up to 6,000 feet (1,800 m) deep
How big is it? • Going from top to bottom and back = two-days (on foot or by mule) • Going through the canyon by raft = two weeks or longer
How old is it? • We can see the rocks at the bottom because of EROSION • Some of these rocks are 2,000 million years old • But, the canyon is 5-6 million years old
How did it form? • Erosion • Rivers are a powerful erosive force over time • Rivers carry about 20 billion tons of rock and soil the oceans each year • How fast erosion occurs depends on the amount of sediment carried and how fast the river moves
How did it form? • Erosive forces continue to shape the Grand Canyon today • But erosion alone cannot explain the width of the Grand Canyon • Scientists think it was widened by tributary drainage systems • the side streams, rivulets, and gullies outside the main river channel • fast-moving landslides called debris flows • These occur when heavy rain or quick snowmelt occurs • The loose rocks and boulders fall down
video • http://www.teachersdomain.org/asset/ess05_vid_canyon/ • http://www.teachersdomain.org/resource/ess05.sci.ess.earthsys.canyon/
Questions • Where is the Grand Canyon? • Which river carved it? • How long does it take to get to the bottom? • How old are some of the rocks at the bottom of the canyon? Is the canyon itself this old? • How did the canyon form?
SOURCES • http://www.nps.gov/grca • http://www.teachersdomain.org/asset/ess05_vid_canyon/