The creation of digital elevation models (DEM) in archaeological applications of geographic information systems (GIS) has, with rare exceptions (e .g . , Kvamme 1 990; Warren 1 990; Wiemer 1 995 ; Madry and Rakos 1 996) , been largely ignored in print. As Kvamme ( 1 990: 1 23 ) has noted, archaeologists are usually concemed with the quality of archaeological data, not the quality of data obtained by computer means. Yet given the same data points, substantively different surfaces can be generated from altemative computer algorithms designed to accomplish the same task. These ditfer­ ences can have significant and unexpected impacts on archaeological investigations .