WEEK 24: NATURAL WONDERS (Celia Mantilla Fernández)

Grand Canyon is an exceptionally deep, steep-walled canyon in north-western Arizona, United States. Formed by the eroding action of the Colorado River, the Grand Canyon is about 443 km (227 mi) long, 8 to 29 km (5 to 18 mi) wide, and more than 1.6 km (1 mi) deep. The entire canyon is extremely beautiful, containing towering buttes, mesas and valleys within main gorge. A spectacular section of the canyon, together with plateau areas on either side, is preserved as the Grand Canyon national Park, which receives about 4 million visitors a year.

The Grand Canyon stretches 349 km (217 mi) across the state’s Colorado Plateau and averages 16 km (10 mi) in width. Beautiful rock formations of layered limestone, sandstone, shale and other rock rise from the canyon floor, which is more than 1.6 km (1 mi) deep. This formation is known as “The Alligator”. The Grand Canyon cuts steeply through an arid plateau region that lies between about 1.525 and 2.745 m (5,000 and 9,000 ft) above sea level. This region, although lacking year-round streams in recent years, is sharply eroded, showing such characteristic forms as buttes; it is interspersed with old lava flows, hills composed of volcanic debris and intrusions of igneous rock. The plateau area has a general downward slope to the south-west and in its upper reaches is sparsely covered with such evergreens as juniper and pinon. Parts of the valley consist principally of such desert plants as agaves and Spanish bayonet. In general the entire canyon area has little soil. The climate of the plateau region above the canyon is severe, with extremes of both heat and cold. The canyon floor also becomes extremely hot in summer, sometimes reaching 46° C (115° F), but seldom experiences frost in the summer.

The Grand Canyon has been sculpted in general by the downward cutting of the Colorado River, which flows the canyon’s lowest portions. Other factors have also played a part. The Kaibab Plateau, which forms the northern rim of the canyon, is about 365 m (1,200 ft) higher than the Coconino Plateau, which forms the southern rim. Water from the northern side has flowed into the canyon, forming tributary valleys, while the streams of the southern plateau flow away in a southerly direction without carving valleys in the canyon walls.

The underlying rock beds also have a south-western slant, with the result that groundwater from the north finds its way into the canyon, but water from the south does not. In the entire canyon region, the rocks have been by jointing and faulting and fractures in the rocks resulting from these processes have contributed to the rapid erosion of the gorge.

This week I practiced my English by helping out my little brother with his homework.