An Objective Approach to Defining Earthwork Geometries Using Subdecimeter Digital Elevation Models

Abstract

Alligator Mound, a ca. 800‐year‐old effigy earthwork located in central Ohio, lies within a 2000 m2 area on the edge of a steeply sloping bluff. This earthwork, with a maximum local relief of approximately 1.5 m, blends into the underlying natural topography, complicating the extraction of measurements of its geometry. To overcome this limitation, a 5 cm × 5 cm gridded digital elevation model (DEM) of Alligator Mound was developed from 2,534,774 elevation points collected from 11 survey locations using a terrestrial light detection and ranging system. This subdecimeter DEM and a derivative local relief model (LRM) capture the subtle topography at this site so that the natural landscape can be objectively filtered from the earthwork. The resulting geometric data (i.e., perimeter, lengths, area, and volume) are compared with subjective historical depictions of this partially denuded earthwork. The results show the value of subdecimeter scale DEMs and LRMs for characterizing subtle features constructed on complex underlying topographies, and for monitoring and/or mitigating long‐term natural and anthropogenic earthwork degradation.

Building Mound A at Poverty Point, Louisiana: Monumental Public Architecture, Ritual Practice, and Implications for Hunter‐Gatherer Complexity

“…Until very recently these studies have emphasized the contents of the mounds rather than the construction methods or techniques and the information that could be garnered from these analyses. Innovations in geoarchaeological research, including geophysical prospection, however, has shifted our perspective on mound architecture to include studies of earthwork geometry (O'Neal, ) and site plans (Burks & Cook, ; Henry, ), engineering, construction methods, selection of soils and sediments, and the pace and duration of construction activities. These studies demonstrate that careful geoarchaeological analyses have much to contribute to understanding mound building and use.…”

From features to fingerprints: A general diagnostic framework for anthropogenic geomorphology

“…This approach simulates lights and shadows to enhance the presence of features captured by the input dataset. Slightly more advanced techniques, based on compound approaches, have been also developed, such as the sky view factor (Figure 4(b)) (Bennett et al, 2012; Devereux et al, 2008; Kennelly, 2008; Štular et al, 2012) or advanced analysis of hillshades (O’Neal, 2012). The advanced use of topographic parameters directly derived from the DEMs allows not only for the visualization, but also for the classification of anthropogenic features.…”