The Adirondack Mountains, a portion of the Appalachian chain, consist of sharply pointed peaks connected by immense ridges. Forty-six mountains have elevations greater than 4000 feet, and Mt. Marcy, with an altitude of 5344 feet, is the highest. Lake-tear-of-the-clouds, near Marcy's summit, is the source of the Hudson River. To the Iroquois Indians, Adirondack meant "tree-eater," a name given to their enemies. Used as Indian hunting territory, the vast wilderness was not penetrated by white man until the late 18th century. Mining began at the end of that century, and Adirondack mines have yielded such ores as iron, zinc, titanium, talc and garnet. The great wealth of Adirondack forests supplied demands for timber in the 19th century and the first decades of the 20th. Alarmed over the denuding of this natural treasure, New York set up the Forest Preserve in 1885. The Adirondack Park now consists of more than two million State-owned acres. Railroad construction after 1871 turned remote forest retreats into popular summer resorts, and the opening of automobile highways in the 20th century made the area accessible for all to enjoy the rugged beauty of the Adirondack mountains.