The world’s longest cave system is an enormous network of 420 miles of twists and turns, with limestone (石灰岩) falling from the ceilings in drops.
Mammoth Cave National Park preserves this unique and historical natural wonder. As large as the limestone cave system is, park officials, estimate there may be another 600 miles of cave passageways that have yet to be explored. The incredible rock formations have resulted in the park being recognized as a World Heritage Site, thanks to its extraordinary size and scientific importance –– making it one of only 13 natural US sites with that title.
The caves were created naturally by the process of limestone wearing away. Rain and rivers slowly break down and shape soft limestone, which creates the vast underground network. Not only are they an amazing destination to visit, but the system also provides drinking water for roughly 40% of the US population, and they’re of historical significance too.
The caves act as a time capsule that preserves over 5,000 years of human history — and the caves’ first explorers were Native Americans, who mined the upper levels of Mammoth Cave. Thanks to the cave system’s atmosphere and natural protection from any kind of human disturbance, the archaeological (考古的) sites have been left in great shape.
Mammoth Cave was established as a national park thanks to strong local support. Back in the 1920s, Secretary of the Interior Hubert Work created the Southern Appalachian National Park Commission in 1925 to survey proposed park sites, including the caves. After years of work acquiring the land for the park, as well as building roads, trails (小径), and public facilities, Mammoth Cave National Park was established on July 1, 1941. The park now receives around 2 million visitors a year, with roughly a quarter taking a tour of the caves –– everything from a cultural tour to the more adventurous climbing tours on offer. The cave supports more than 130 wildlife species, such as the eyeless cavefish, which has adapted to the lightless environment by no longer growing eyes, and the cave crayfish.
【小题1】What has made Mammoth Cave National Park a World Heritage Site?| A．The wildlife species. | B．The rock formations. |
| C．The cave passageways. | D．The scientific discovery. |
| A．They are an amazing destination to visit. |
| B．They were first explored by Native Americans. |
| C．They provide drinking water for the Americans. |
| D．They preserve human history over 5000 years. |
| A．It took a lot of work to establish the park. |
| B．Local people donated the land for the park. |
| C．Around 2 million people visit the caves annually. |
| D．The site of the park was decided by the secretary. |
| A．Taking cultural and adventurous tours |
| B．Preserving a unique and historical wonder |
| C．Exploring the world’s longest cave system |
| D．Establishing Mammoth Cave National Park |
