Soil Genesis, Classification, and Mapping
Cultural implications of architectural mortar and plaster selection at Mesa Verde National Park, Colorado
Mesa Verde is one of America’s most fascinating National Parks. Located in the Four Corners region of the Southwestern United States, the park is home to hundreds of prehistoric cliff dwellings once occupied by the Ancient Puebloans. Our research at Ruin 12 and Spruce Tree House: (1) examines the temporal consistency, or lack thereof, in mortar source selection between two sites; (2) examines patterns of mortar selection at distinct locations within each site in an effort to determine the extent and makeup of the mortar source primary resource access group; (3) and provides a regional perspective on the similarities and differences in mortar procurement. In order to provide a thorough geochemical characterization of mortar and plaster samples, analytic techniques including x-ray diffractometry (XRD), inductively coupled plasma – mass spectrometry (ICP-MS), electron microscopy (SEM-EDS) have been utilized. Results of this research indicate the existence of a temporal trend in mortar selection at Spruce Tree House very similar to that originally described for Mug House by Rohn (1971). Early cliff dwelling masons preferred using a combination of mesa top loess and sandy soil for construction. During the middle period of occupation, this gave way to residual soil sources closer to the construction efforts in the cliffs. Finally, during the latest period of cliff house construction, masons began incorporating crushed shale into the mortar. This temporal trajectory of mortar selection has now been shown at two Mesa Verde sites, and may extend to a large portion of similar cliff house sites within the Mesa Verde proper. The results from Spruce Tree House also indicate that households occupying the site at any one time shared equal access to mortar sources. Plaster analysis using SEM-EDS identified rich white-washes as elementally distinguishable layers of calcium carbonate. Tan and red earthen colored layers exhibited more subtle elemental differences. Results suggest a variety of source materials were used for plastering, as well as a variety of recipes depending on the intended effect. This project was undertaken by Shane Rumsey, MA Candidate, Dept. of Anthropology, Univ. of Nevada, Las Vegas. Collaborators: Shane Rumsey; Dr. Karen Harry (Dept. of Anthropology and student advisor); Patrick Drohan (PSU Soil Characterization Lab); Rebecca Carr (currently Casa Grande Ruins National Monument).
