Sometimes erroneously included in the Appalachian system, the Adirondacks are geologically related to the Canadian Shield and are generally considered a southern extension of it. About half of the total acreage of the Adirondack Mountain range is part of the New York State Forest Preserve. The region has hundreds of large and small lakes, notably Lakes Placid and George and Schroon, Cranberry, Upper and Lower Saranac, and Raquette lakes. The Hudson, Ausable, and Black rivers rise in the Adirondacks, and numerous streams cut through the mountains. Adirondack Park is thickly forested with spruce, pine, and hemlock and with some types of deciduous trees.
Wildlife is abundant, although some of the larger species are diminishing in number.
There are no large cities or major industrial zones here. The area is a popular all-year sport and resort region. Because the climate is beneficial to sufferers from pulmonary ailments, several sanatoriums have been established here. Lumbering is carried on by private landholders, and some iron ore, talc, and zinc are mined.