It involves the partitioning of the terrain intoconceptual spatial entities based upon criteria that include morphology (form), genetics (process), composition and structure, chronology, environmental system associations (land cover, soils, ecology), as
well as spatial topological relationships of surface features (landforms). Historically, the power of human visualization was primarily relied upon for analysis, introducing subjectivity and biases with respect to selection of criteria for terrain segmentation and placement of boundaries.