Wind, water, fire, and ice—these powerful natural forces have shaped the land of America in the past. They are still changing it today. The Colorado River slowly cut down through stone to make the Grand Canyon (大峡谷). Long ago, ice sheets cut Yosemite Valley and the Great Lakes, and glaciers are still on the move in Alaska. Wind and rain storm hit the land from time to time. Fires sometimes burn down forests and destroy the homes of wild animals. This happened in Yellowstone Park in 1988. Dead volcanic mountains such as Haleakala on Maui and Crater Lake in Oregon are beautiful to look at. But there are several active volcanoes in the U.S., especially along the Pacific Coast. There are also many earthquakes in this area. Scientists can do nothing to control earthquakes or volcanoes. This was shown clearly on May 18, 1980. At 8:32 that morning, Mt. St. Helens (圣·海伦斯火山) in Washington state broke out. The top of the mountain was blown off. Over 60 people—campers, scientists, journalists, forest workers—were killed. Hundreds of square miles of forests were knocked down. In towns over 100 miles away, day suddenly became night. An ash cloud hid the sun for many hours. Towns and fields in Washington, Oregon, and Idaho were covered with dirty gray ash. Scientists knew that Mt St Helens might erupt (爆发) soon. But no one could say when. And no one expected the terrible strength of the eruption. Many people were surprised and unready. Harry R. Truman, 84, owned a small hotel in Mt. St Helens. Scientists had asked people to move away because the volcano was becoming dangerous. But Harry Truman would not leave his home. Now it is covered with many feet of dirty ash. A small cross stands above the place where Harry probably died. Perhaps it is better that he did not see the destruction of Mt St Helens, the once beautiful lake, and the forests. But slowly, life is returning to the dead area around the mountain. Grasses and small plants are beginning to grow again. Deer and birds have been seen. The land will never be the same as it once was. Perhaps Mt St Helens will erupt again. But this is all part of nature’s pattern of change, and man has little power to control it.