Marble Mountain is a mountain in Warren County, New Jersey. The summit rises to , and is located in Harmony and Lopatcong Townships, overlooking the Delaware River; along with Chestnut Hill on the Pennsylvania side, Marble Mountain forms Weygadt Gap or the Little Water Gap.A Paddler's Guide to the Delaware River: Kayaking, Canoeing, Rafting, Tubing; Gary Letcher; Rutgers University Press; New Brunswick, NJ; 2002; p 137
It is part of the New York–New Jersey Highlands of the Appalachian Mountains, although somewhat isolated to the west of the main body of the Highlands.
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