The Adirondack Mountains are an unusual geological formation located in the northeastern lobe of Upstate New York in the United States. The mountains rise in Clinton, Essex, Franklin, Fulton, Hamilton, Herkimer, Lewis, St. Lawrence, Saratoga, Warren, and Washington counties. Unlike other mountain ranges that run along fault lines, the Adirondack mountains resemble a dome. They were formed by recent uplift that has exposed previously deeply buried and ancient rocks more than a billion years old.
