Karst is the name applied to topography that develops on land underlain by soluble rocks such as limestone, gypsum, and salt. Karst terrain is characterized by solution features such as caves, sinkholes, depressions, enlarged joints and fractures, and internal drainage. The name was derived from the Karst region of Slovenia (part of the former Yugoslavia), which is underlain by limestone. This report summarizes the occurrence of karst features on the Colorado Plateau of Arizona. The first section briefly discusses the three major types of karst features on the Plateau: breccia pipes, surficial karst, and deep-seated salt karst. The remainder of the report focuses on salt karst in the Holbrook basin.