Historical Features are physical or cultural features that are no longer visible on the landscape. Examples: a dried up lake, a destroyed building, a hill leveled by mining. The term makes no reference to the age, use, or any other aspect of the feature. A ghost town, for example, is not a historical feature if it is still visible.
Gap - Low point or opening between hills or mountains or in a ridge or mountain range (col, notch, pass,
saddle, water gap, wind gap).