Appalachian Mountains

The Appalachian Mountains (Appalaches), 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, its surrounding hills and the dissected plateau region. 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 first of many mountain-building events that shaped the Appalachians occurred about 1 billion years ago when the interior portion of what is now North American was part of the supercontinent Rodinia. Many of the rocks and minerals that were formed during that event can currently be seen at the surface of the present Appalachian range. The mountains once reached elevations similar to those of the Alps and the Rockies before experiencing natural erosion. The Appalachian range is a barrier to east–west travel, as it 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. Partly because the range runs through large portions of both the United States and Canada, and partly because the range was formed over numerous geologic time periods (one of which is sometimes termed the Appalachian orogeny), writing communities struggle to agree on an encyclopedic definition of the mountain range.