Research topic: Grand Canyon

Grand Canyon great gorge of the Colorado River, one of the natural wonders of the world; c.1 mi (1.6 km) deep, from 4 to 18 mi (6.4-29 km) wide, and 217 mi (349 km) long, NW Ariz. The canyon shows in its rocks the repeated geological sequence of uplift, erosion (due to the river's constant wearing force), submergence, and deposition of materials. The multicolored rocks, the steep and embayed rims, and the isolated towers, mesas, "temples," and other eroded rock forms catch the contrast of sun and shadow and glow with changing hues of great beauty. Plant life on the canyon walls varies from... Read more