سؤال قراءة ستيب محلول — فهم التفاصيل (تدريب 8034)

1) Established in 1872, Yellowstone National Park is not only the oldest national park in the United States but also in the world. It is also one of the largest, and probably the best-known, national parks in the United States. It is located principally in northwestern Wyoming and partly in southern Montana and eastern Idaho. The park, which forms a square like rectangle, is 63 miles (101 kilometers) from north to south and 54 miles (87 kilometers) from east to west at its widest point; it covers an area of 3,472 square miles (8,992 square kilometers). Grand Teton National Park lies to the south, and on all other sides Yellowstone is surrounded by national forests. Yellowstone’s headquarters are at Mammoth Hot Springs near the northern entrance to the park. 2) Most of the park consists of broad volcanic plateaus with an average elevation of about 7,875 feet (2,400 meters). Three mountain ranges, each running roughly north to south, protrude into the park: the Gallatin Range in the northwest, the Absaroka Range in the east. and the northern extremity of the Teton Range along the park’s southwestern boundary. The tallest mountains in the park are in the Absarokas, where many summits exceed elevations of 10,000 feet (3,050 meters). The range’s Eagle Peak, on the park’s boundary in the southeast is the high point reaching 11,358 feet (3,462 meters). Within its rugged mountains are spectacular deep glacier carved valleys. 3) Yellowstone is also known for its many scenic lakes and rivers. The park’s largest body of water is Yellowstone Lake, which has a surface area of 132 square miles (342 square kilometers) and lies at an elevation of 7,730 feet (2,356 meters), making it the highest mountain lake of its size in North America. The Yellowstone River enters at the southeast corner, flows generally northward (including through Yellowstone Lake), and exits near the northwest corner of the park. The river’s Yellowstone Falls, located in the north-central part of the park, descend in two majestic cascades. The falls constitute the western end of the spectacular Grand Canyon of the Yellowstone. There the river has cut a gorge 19 miles (30 kilometers) long, between 800 and 1,200 feet (240 and 370 meters) deep, and up to 4,000 feet (1,200 meters) wide. The walls of the canyon are brilliantly colored in hues of red, pink, yellow, buff, lavender, and white. 4) Yellowstone’s other noted geysers and thermal features include Giantess Geyser, with a two- to six-month wait between eruptions; Excelsior Geyser, which rarely erupts but discharges thousands of gallons of boiling water per minute; and the Fountain Paint Pots, with pink, plopping mud geysers, fumaroles, and a blue hot-spring pool. Steamboat Geyser can throw water to heights of 300 feet (90 meters) and higher and is the world’s highest erupting geyser. Mammoth Hot Springs consists of a broad terraced hillside of travertine (calcium carbonate) deposited there by dozens of hot springs; some of the dazzling white rock is tinted by microorganisms on the rock. 5) Yellowstone’s climate is influenced by the park’s high average elevation, location deep within the continent, and mountainous terrain. Temperatures almost always decrease with elevation gain. Because of Yellowstone’s large area and variegated topography, weather conditions at different locations within the park can vary widely at any given time. In addition, conditions can change dramatically in a short period of time at one location. 6) Summer days are warm and relatively sunny, with daytime temperatures reaching about 80° F (27° C) in July at lower elevations before dropping to nighttime lows in the 40s or 50s F (about 10° C); temperatures are usually cooler higher in the mountains. Although precipitation totals in the warm months generally are light, summer afternoon thunderstorms are common. Winters are cold and snowy, as temperatures rarely rise above the mid-20s F (about –4° C) and often drop to 0° F (–18° C) or lower at night. Snowfall is heavy in most areas, especially at higher elevations, and typically begins in early autumn and continues into April or May. 7) About four-fifths of the park’s area is forested, and the vast majority of the tree growth consists of lodgepole pines. Among the several other conifer species in the park are whitebark pine, found at higher elevations; and Douglas firs, which dominate at lower elevations. Cottonwoods and willows grow along streams, and stands of aspens occur in many sections. A significant event in Yellowstone’s more recent history was the great fire of 1988 that charred some two-fifths of the park’s forestlands. The forests subsequently have recovered, although areas have been subject to damage by insect pests. Hundreds of types of wildflowers thrive in a variety of habitats. Common species include phlox, lupines, cinquefoils, larkspurs, and Indian paintbrushes. 8) Yellowstone boasts the greatest assemblage of mammals—more than five dozen species—in the United States, outside of Alaska. Bison (buffalo), the largest of the mammals, were brought back from near extinction at the beginning of the 20th century. Other large mammals often seen in Yellowstone include elk (wapiti), mule deer, black bears, foxes, and coyotes. There are smaller populations of brown (grizzly) bears, bighorn sheep, pronghorns, mountain goats, and moose. Bobcats are thought to be present throughout the park, but their numbers are unknown, and there are occasional sightings of lynx and pumas (mountain lions). Common smaller mammals include badgers, martens, weasels, river otters, hares and rabbits, shrews, a variety of bats, and many species of small rodents. Wolves were successfully reintroduced into Yellowstone in 1995 and are now found throughout much of the park. Beavers have also made a significant comeback, and several hundred live along streams and lakes.