The Appalachian Mountains is the most prominent landform in Eastern North America ia a system of low mountains extend for nearly 2,000 miles from Canada to Northern Alabama.

 The Appalachian Mountains, often called the Appalachians, are a system of mountains in eastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. It once reached elevations similar to those of the Alps and the Rocky Mountains before naturally occurring erosion. The Appalachian chain is a barrier to east-west travel, as it forms a series of alternating ridgelines and valleys oriented in opposition to most roads running east or west.

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Definitions vary on the precise boundaries of the Appalachians. The United States Geological Survey (USGS) defines the Appalachian Highlands physiographic division as consisting of thirteen provinces: the Atlantic Coast Uplands, Eastern Newfoundland Atlantic, Maritime Acadian Highlands, Maritime Plain, Notre Dame and Mégantic Mountains, Western Newfoundland Mountains, Piedmont, Blue Ridge, Valley and Ridge, Saint Lawrence Valley, Appalachian Plateaus, New England province, and the Adirondack provinces. A common variant definition does not include the Adirondack Mountains, which geologically belong to the Grenville Orogeny and have a different geological history from the rest of the Appalachians.

Today we are going to talk about the Mammoth Cave:

The Mammoth Cave is the largest known underground cave system in the World.

The first person to ever enter the cave probably visited more than 4,000 years ago, but it wasn’t until 2,000 years ago that Native Americans of the Early Woodland Period started using the cave for mining. These primitive miners searched the complex, dark systems for precious minerals. Traces of their past can be evaluated based on the objects they left behind: slippers, torches, mussel shells.

In the 18th century, European settlers discovered the cave. They found the cave was abundant with calcium nitrate, which could be used to make black gunpowder — a precious commodity during the War of 1812. The cave’s worth increased dramatically and the settlers enlisted slaves to extract the substance. After the war, in 1816, interest in the cave as spectacle peaked, and there have been tours ever since. Since then, the cave has been used as  a hospital, a choir space and a church, among other things. It was established as Mammoth Cave National Park in 1945.

Other key dates in Mammoth Cave’s history:

• July 1, 1941 – Mammoth Cave National Park is established.
• September 18, 1946 – With the end of World War II, Mammoth Cave undergoes its formal introduction as the 26th unit of the National Park Service.
• October 27, 1981 – Mammoth Cave National Park is designated as a World Heritage Site.
• September 26, 1990 – Mammoth Cave National Park is designated as an International Biosphere Reserve.