Left: Michele Koons, foreground, and Jennie Sturm, background, surveying with a total station in the town. Right: Jennie Sturm using ground-penetrating radar in the town.
Pin flags marking a line of quincha that once formed the walls of houses in the town.
Plan-view
map of the colonial church created from total station points.
The use of computer-based mapping and imaging equipment, referred to as digital methods, are efficient ways to gather large amounts of data quickly and accurately. Because these methods are noninvasive, information about a site can be collected over a large area efficiently, and still preserve the site for future study. These methods have included total station mapping, geophysical methods (ground-penetrating radar and magnetometry), and global positioning/GIS mapping.
Ground-penetrating radar (GPR) mapping was used at the site briefly in 2004, and more extensively in 2005. Total station mapping was used extensively in 2005 and 2006. Future mapping plans include using global positioning system (GPS) mapping to incorporate into a geographic information system (GIS) for 2007, and using additional geophysical mapping, including magnetometry, in 2008. Each year is summarized below:
2004: One GPR grid was collected at the southernmost edge of the town, at the base of the church complex mound. One reflection of interest was noted in these data, which excavation later confirmed to be a large chicha pot. This was an interesting discovery that suggested the GPR method would be a successful and beneficial way to map features in the unique sediments of this site. Further interpretations from this grid were limited, however, as few additional excavations were done at the time to follow up on this survey.
2005: Total station mapping was undertaken to map remnant surface architecture in the church and town. In the church compound, this primarily includes adobe walls, and in the town, remnant quincha, or cane walls. A total station is a digital theodolite that records the x, y, and z information about a given location within a grid. Using this spatial information, a variety of maps can be created, including point maps and three-dimensional topography maps.
In addition to mapping the quincha, we focused on mapping other features
in the town as well, including middens, posts, and topography.
Five GPR survey grids were placed in the town in areas that appeared from surface mapping to be housing units, roads, and a plaza. In general, these surveys were successful at mapping buried features such as floor and road surfaces, buried adobe walls, and a fire hearth in the space currently believed to be the plaza.
2006: Total station mapping continued to map newly uncovered architecture
in the church and town. In addition to mapping architecture, this field
season focused on mapping surface artifacts, topography, and the edge
of the terrace. This helped to create a more complete and accurate “picture”
of the town’s grid-pattern layout, a trademark expression of Spanish
town planning.
2007: Total station mapping continued to be utilized to map new excavations, newly uncovered architecture (both quincha and adobe), artifacts, and features. Work continued in creating a comprehensive GIS database, a critical component in studying space and architecture at this site.
Ground-penetrating radar images. The top image is an amplitude slice-map, showing the distribution of reflection strength across a given area. The bottom image is a raw, two-dimensional profile. Both showed an area of strong reflections that were hypthosized to be some sort of floor layer or platform.
A three-dimensional map showing topography and features of the colonial town (and part of the church) generated from total station points. These data were also incorporated into a GIS database.