Appalachian Mountains

The Appalachian Mountains, often called the Appalachians, are a mountain range in eastern to northeastern North America. They run from the Island of Newfoundland in Canada all the way southwestward to Central Alabama in the United States. The highest peak in this range is Mount Mitchell in North Carolina.

The Appalachian Mountains are older than the Rocky Mountains and contain some of the oldest rocks on Earth. Their formation began when the continents of Laurentia and Amazonia collided. Over time, these mountains were shaped by natural erosion, leaving the beautiful ridges and valleys we see today.

These mountains have played an important role in history. Today, they are famous for the Appalachian Trail, a long hiking trail that runs from Mount Katahdin in Maine to Springer Mountain in Georgia. The trail passes through many parts of the Appalachian range and even continues into Canada through the International Appalachian Trail in New Brunswick and Quebec.

Etymology

When explorers came to the northern coast of Florida in 1528, they found a village of Native Americans near Tallahassee, Florida. The villagers called their home Apalchen or Apalachen. Spanish explorers changed this name to Apalachee and used it for the people and the land far to the north.

Later, maps used this name for the mountains. In the late 1800s, “Appalachian” became the common name for the whole mountain range. Some people called them the “Allegheny Mountains.”

Geography

The Appalachian Mountains, also called the Appalachians, are a mountain range in eastern and northeastern North America. The word "Appalachian" includes different areas and mountain systems, as well as the land around them. The United States Geological Survey and the Geological Survey of Canada use a common way to describe these areas, called physiographic regions.

The Appalachian Highlands is one of eight physiographic regions in the United States, and the Appalachian Uplands is one of seven in Canada. These regions help make clear maps of the mountains.

The Appalachian Mountains stretch from the Atlantic Ocean in New England to the border of the coastal plain through the central and southern Atlantic states. To the northwest, the Allegheny and Cumberland plateaus slope toward the Great Lakes and the interior plains. A special feature is the Great Appalachian Valley, which divides the mountain system into two parts in the south but lies west of all the ranges in the north. The mountain tops generally rise to similar heights, especially in the central part, with ridges and valleys running parallel to the system.

In Pennsylvania, many tops rise above 2,500 ft (800 m), including Mount Davis and Blue Knob, which exceed 3,000 ft (900 m). In Maryland, Eagle Rock and Dans Mountain reach notable heights. West Virginia has over 150 tops above 4,000 ft (1,200 m), with Spruce Knob at 4,863 ft (1,482 m) being the highest. The Blue Ridge Mountains, starting in Pennsylvania as South Mountain, reach over 2,000 ft (600 m) in Virginia, with tops like Hawksbill Mountain and Whitetop Mountain. In the southern Blue Ridge, major tops include Mount Mitchell and Mount Rogers.

The Appalachian belt includes plateaus sloping southward to the Atlantic Ocean in New England and southeastward to the coastal plain border through the central and southern Atlantic states. To the northwest, the Allegheny and Cumberland plateaus decline toward the Great Lakes and the interior plains. A notable feature is the long chain of broad valleys, including the Great Appalachian Valley, which divides the mountain system in the south but lies west of all ranges in the north. The tops in every part of the system rise to fairly uniform heights, and especially in the central section, the ridges and valleys follow the trend of the system itself. No tops reach the region of perpetual snow.

The second level in the physiographic classification for the USGS is "province," which matches the term Canada uses for its political subdivisions. This means the terminology differs below the region level. The lowest level is "section."

The Appalachian Uplands are one of seven physiographic divisions in Canada. Canada's Geological Survey does not use the same classification system as the USGS below the division level. It divides the Appalachian Uplands into 13 subsections across four political provinces.

Although the Appalachian Highlands and Appalachian Uplands are mostly continuous across the U.S./Canada border, the St. Lawrence Valley is classified differently. In the United States, it is part of the Appalachian Highlands, but in Canada, it is part of the St. Lawrence Lowlands. This includes areas around Montreal, Anticosti Island, and the northwest coast of Newfoundland. Some plateau areas, though not true mountains, are called "mountains," especially in eastern Kentucky and West Virginia. In Ohio and New York, glaciation has rounded ridges and filled valleys, creating hilly landscapes instead of mountains.

Sources before physiographic regions categorized the Appalachians into three sections:

• Northern: From Newfoundland and Labrador to the Hudson River, including ranges in Canada, Quebec, New Brunswick, Maine, New Hampshire, Vermont, Massachusetts, Connecticut, and New York.

• Central: From the Hudson Valley in New York to the New River, covering areas in New York, Pennsylvania, Maryland, Virginia, and West Virginia, including the Valley Ridges, New York–New Jersey Highlands, Taconic Mountains, and parts of the Blue Ridge.

• Southern: From the New River, including the Blue Ridge Mountains, Ridge-and-Valley Appalachians, and Cumberland Plateau, stretching through Virginia, West Virginia, Kentucky, Tennessee, and Alabama.

Geology

Main article: Geology of the Appalachians

The Appalachian Mountains formed over a billion years ago as Earth's plates moved. These movements made mountains that later broke apart and created oceans. Over time, these changes made the landscape we see today.

Grenville orogeny and formation of Supercontinent Rodinia

Further information: Grenville orogeny

A big collision happened over a billion years ago when a land called Laurentia crashed into another land, Amazonia. This and other collisions formed a huge land called Rodinia. Mountains grew where these lands met. Parts of the Appalachians, like the Blue Ridge Mountains and the Adirondacks, come from rocks made during this time.

Breakup of Rodinia and formation of the Iapetus Ocean

After the mountains formed, the continents moved apart again. The mountains wore down from weather and ice, and sediments filled up valleys. An ocean called the Iapetus Ocean formed between the lands. Over millions of years, layers of mud and shells turned into limestone, which we still see today.

Volcanic activity happened around 600 million to 560 million years ago, leaving marks in places like Mount Rogers and Whitetop Mountain. Rocks from this time can be found in the Blue Ridge, such as those in Montgomery County, Virginia and the Catoctin Formation.

Taconic Orogeny

Main article: Taconic orogeny

Later, around 500 to 470 million years ago, the plates moved back together. A volcanic island chain crashed into North America, creating new mountains. This event, called the Taconic Orogeny, helped build parts of New England and Pennsylvania. After about 60 million years, this mountain-building stopped, but it added much to the land we see today.

The Taconic Orogeny was one of four big collisions that helped form the Appalachians, leading up to the time when North America and Africa came together.

Acadian orogeny

Main article: Acadian orogeny

The next event, the Acadian Orogeny, happened between 375 and 359 million years ago. Pieces of land from a place called Gondwana crashed into North America, closing the southern part of the Iapetus Ocean and making high mountains. After this, Gondwana moved away, opening a new ocean called the Rheic Ocean.

Alleghenian orogeny and Supercontinent Pangea

As the plates kept moving, more land pieces crashed into North America. About 270 million years ago, North America and Africa finally met, forming a supercontinent called Pangea. The Appalachians were part of a big mountain chain that stretched into places like Morocco and Scotland.

By the end of a big time period called the Mesozoic Era, the Appalachian Mountains had worn down to almost flat land. But later, during the Cenozoic Era, they rose up again, shaping the mountains we see today.

Mineral resources

The Appalachian Mountains have important resources like coal, including anthracite and bituminous coal. Coal mining has affected the environment. Rules were made to protect the mountains, and new discoveries of natural gas in places like the Marcellus Shale and Utica Shale have brought attention back to the area.

The mountains also contain metals like iron and zinc.

Drainage

Rivers and streams in the Appalachians have interesting paths. Many flow across the mountains instead of following them. The main divide for water runs along the mountains, separating the eastern seaboard from the Midwest of the United States. In the north, rivers like the Hudson River flow south, shaped by old glaciers from ice ages.

The Appalachian region marks the divide between the eastern seaboard of the United States and the Midwest region. The Eastern Continental Divide follows the Appalachian Mountains from Pennsylvania to Georgia.

Ecology

The Appalachians, especially in the middle and southern parts, have lots of plants and animals. The way the mountains and valleys run from north to south helps animals and plants move to where they can live best.

Plants in the Appalachians grow differently depending on the rocks, how far north or south they are, how high they are, and how much rain they get. Trees there include evergreens like spruce and fir, and trees that lose their leaves like maple and oak. There are also many bushes, herbs, and flowers, some of which are used for medicine.

Animals in the Appalachian forests include squirrels, rabbits, deer, black bears, and many birds. Salamanders are very important, with many kinds living on the forest floor. Streams are home to many kinds of fish, including trout. The mix of plants and animals makes the Appalachians a special place for nature lovers.