The Adirondack Mountains are a vast New York wilderness of rocky peaks, sheer cliffs, narrow valleys, wooded slopes, and sparkling lakes. Forty three mountains rise 4000 feet or higher, and Mount Marcy, at 5344 feet, is the highest; near its summit is Lake Tear-of-the-Clouds, the source of the Hudson River. The name Adirondack, meaning "tree-eater," was a derisive term used by Iroquois Indians for some of their Algonkian enemies. Long used as Indian hunting territory, the region was not penetrated by white men until the late 18th century. Mining began at the end of that century and produced iron, zinc, titanium, talc, and garnet. Adirondack forests supplied timber during the 19th century and the first decades of the 20th, but concern over this denuding led New York to establish the Forest Preserve in 1885. The Adirondack Park now includes more than two million state-owned acres, and transportation improvements after 1871 and in the 20th century opened the once-remote region as a popular destination for summer resorts and broader public enjoyment.