Probably you have seen photographs of the Grand Canyon  , the great valley in the desert country of Arizona. But you must go there yourself to feel its true size and beauty. Tie Grand Canyon is one of the greatest natural wonders of the world.     The Colorado River formed the Grand Canyon over mil lions of years. Slowly, the river cut down through hard rock. At the same time. the land was rising. Today. the canyon is one and a half kilometres deep and 445 kilometres long. The el dest rocks at the bottom of the canyon are more than 1 billion years old. The width varies from about 200 metres to 29 kilo metres across. The rim   or top of the canyon is about 2, 300 metres above sea level tin the South Rim, and about 3,000 metres on the other side, the North Rink As a result, there are different kinds of plants and animals on opposite sides of the canyon. The South Run is dry desert country. The North Rim has tall forests. The canyon looks different at different times of day. and in different seasons and weather.  At sunrise anti sunset the red. gold, brown, and orange colours of the rocks are especially dear and bright.  In winter, the canyon is partly covered with snow.      The view from the South Rim of the Grand Canyon is the best.  Most visitors come to the South Rim and stay in camp- grounds or hotels. Every point along the canyon' s edge offers a different view.    The North Rim of the Canyon is quieter, h takes all day to drive there from the South Rim because there is only one bridge across the Colorado River. On the way, you go through Navado Indian lands, and a colourful pink desert called "The Painted Desert". You can walk clown into the Grand Canyon, or you can go down oil the back of a mule  .  You can also lake a boat trip down the Colorado River, and camp on the bea ches at night. But whether you see the Grand Canyon from the top or the honom, it will be an experience that you will never forget. If you go to visit the canyon you'd better go to  _  .
the South Rim the North Rim the bottom the top of a tree