Passage6

Questions 26 to 30 are based on thefollowing passage.

YellowstoneNational Park, established by the U.S. Congress as a national park on March 1,1872, is located primarily in the U.S. state of Wyoming, though it also extendsinto Montana and Idaho. The park was the first of its kind, and is known forits wildlife and its many geothermal地热的) features,especially Old Faithful Geyser, one of the most popular features in the park.It has many types of ecosystems, but the subalpine(亚高山带的)forest is dominant

American Indianshave lived in the Yellowstone region for at least 11,000 years. The region wasbypassed during the Lewis and Clark Expedition in the early 1800s. Aside fromvisits by mountain men during the early to mid 1800s, organized exploration didnot begin until the late 1860s. The U.S. Army was commissioned to oversee thepark just after its establishment. In 1917, administration of the park wastransferred to the National Park Service, which had been created the previousyear. Hundreds of structures have been built and are protected for theirarchitectural and historical significance, and researchers have examined morethan 1,000 archaeological sites.

YellowstoneNational Park spans an area of 3,468 square miles, comprising lakes, canyons,rivers and mountain ranges. Yellowstone Lake is one of the largest high-altitudelakes in North America and is centered over the Yellowstone Caldera, thelargest super-volcano- on the continent. The caldera is considered an active volcano;it has erupted with tremendous force several times in the last two million years.Half of the world's geothermal features are in Yellowstone, fueled by ongoingvolcanic activities. Lava flows and rocks from volcanic eruptions cover most ofthe land area of Yellowstone. The park is the centerpiece of the Greater YellowstoneEcosystem, the largest remaining nearly-intact ecosystem in the Earth'snorthern temperate zone.

Hundreds ofspecies of mammals birds, fish and reptiles have been documented, includingseveral that are either endangered or threatened. There are almost 60 speciesof mammals in the park. Apart from wildlife, there are 1, 700 species of treesand other plants native to the park. Another 170 species are considered to beexotic species and are non-native.

As one of themost popular national parks in the United States, Yellowstone provides numerousrecreational opportunities including hiking, camping, boating,fishing andsightseeing. Paved roads provide close access to the major geothermal areas aswell as some of the lakes and waterfalls. Since the mid 1960s, at least 2 milliontourists have visited the park almost every year. Nine hotels and lodges, withtotal of 2,238 rooms and cabins, are available to tourists from all over the world.Hundreds of employees work either permanently or seasonally for the NationalPark Service.

 
The Old Faithful Geyser is probably____