Appalachian Mountains

The Appalachian Mountains, often called the Appalachians, are a mountain range in eastern to northeastern North America. Here, the term "Appalachian" refers to several different regions associated with the mountain range, and its surrounding terrain. The general definition used is one followed by the US Geological Survey and the Geologic Survey of Canada to describe the respective countries' physiographic regions. The US uses the term Appalachian Highlands and Canada uses the term Appalachian Uplands. (The Appalachian Mountains are not synonymous with the Appalachian Plateau which is one of the provinces of the Appalachian Highlands). The Appalachian range runs from the Island of Newfoundland southwestward to Central Alabama in the United States. (It crosses the 96-square mile archipelago of Saint Pierre and Miquelon, an overseas collectivity of France, meaning it is technically in three countries). The highest peak of the mountain range is Mount Mitchell in North Carolina at , which is also the highest point in the United States east of the Mississippi River. The range is older than the other major mountain range in North America, the Rocky Mountains of the west. Some of the outcrops in the Appalachians contain rocks formed during the Precambrian era. The geologic processes that led to the formation of the Appalachian Mountains started 1.1 billion years ago. The first mountain range in the region was created when the continents of Laurentia and Amazonia collided, creating a supercontinent called Rodinia. The collision of these continents caused the rocks to be folded and faulted, creating the first mountains in the region. Many of the rocks and minerals that were formed during that event can currently be seen at the surface of the present Appalachian range. Around 480 million years ago, geologic processes began that led to three distinct orogenic eras that created much of the surface structure seen in today's Appalachians. During this period, mountains once reached elevations similar to those of the Alps and the Rockies before natural erosion occurred over the last 240 million years leading to what is present today. The Appalachian Mountains are barrier to east–west travel, as they forms a series of alternating ridgelines and valleys oriented in opposition to most highways and railroads running east–west. This barrier was extremely important in shaping the expansion of the United States in the colonial era.