The Adirondack Mountains in New York are an extension of the Laurentians, although they are sometimes mistakenly included with the Appalachian Mountains. The foothills of the Laurentian range also extend into northeastern Ontario, where they are known as the Laurentian Highlands, Madawaska Highlands, and the Opeongo Hills.
The Laurentian Mountains are one of the oldest mountain ranges in the world. They contain rocks deposited during Cambrian times, 540 million years ago. The Laurentians are a central part of the Grenville orogeny, formed 1,100–1,000 million years ago.
- "Laurentian-Mountains", Encyclopædia Britannica. Retrieved from http://concise.britannica.com/ebc/article-9369832/Laurentian-Mountains on March_9, 2007