Antithetical premises of a static versus dynamic Andean landscape, inoperable canal gradients must be explained by social parameters such as poor surveying or construction techniques. The paradigm of Plate Tectonics and evidence of ongoing crustal convergence support an anternative premise of continuos, gradual landscape alteration and ground slope change. This premise provides a physical explanation for why abandoned canals often exhibit uphill gradients and ancient monuments are frequently not level. However, this premise also requires that complex methods in the engineering analysis of slope altered structures be made explicit.