The Marlboro Mountains, sometimes Marlborough Mountains, are a group of hogbacked mountains arranged in a ridge extending from Newburgh, New York, to just south of Kingston, New York. Considered to be part of the Ridge and Valley Appalachians, the mountains, which reach elevations over 1,100 feet, form an imposing geologic barrier just west of the Hudson River. They subdivide the relatively flat Hudson River Valley (a section of the Great Appalachian Valley) to create the Wallkill Valley further west. Rising abruptly on their eastern flanks, the Marlboro Mountains are known for their sweeping views of the region.