 The third mountainous region, occupying the northeast part of the state, is known as the Adirondack Mountains.The region is bounded to the south by the Mohawk River, south of which the highlands become part of the Allegheny Plateau, in the form of broad, irregular hills, broken by the deep ravines of streams.The valley of the Mohawk separates the Allegheny Plateau to the south from the highlands leading to the Adirondacks to the north, reaching its narrowest point in the neighborhood of Little Falls, the Noses, and other places.