1. Archaeologist are very interested in studying activity areas outside of pithouses. These extramural features are difficult to locate using standard archaeological techniques, and identifying these features using a cesium magnetometer was a main objective of this project. A secondary objective was to identify pithouse central hearths, walls, and floors. We acquired the data at a 1,000-year-old pithouse village site located in the understudied Mimbres Mogollon cultural area, just to the north of Silver City, NM. Dr. Roth’s University of Nevada-Las Vegas Archaeological field school’s excavations to further understand the transition of these people from a foraging society to a sedentary culture will be guided by the results of the cesium magnetometer survey. The results of the magnetometer survey will also contribute to understanding under what range of environments this technique is capable of identifying features of archaeological interest. During the course of the project we observed that rocks scattered on the surface have a magnetic signal that was strong enough to cause us concern. Several rocks were collected and analyzed to determine the strength of their magnetic signal, and to understand their impact on our survey. Returning to the site would enable us to replace the rocks collected and record their effects on interpreting signals of pithouses and other features. The Earth’s magnetic field is approximately 51,000 nT at the latitude of the study site and small variations in the magnitude of the Earth's local magnetic field are produced by the magnetic properties of the soils and subsurface features. The figure below shows how the magnetic field of an object can alter the magnitude of the Earth’s local magnetic field. These anomalies are caused by anything with a remnant or induced magnetic field such as variation in soil composition, rocks, and anthropogenic features. Previous work has documented the cesium magnetometer’s ability to record the magnetic signature of features of interest at our study site. The Geometric Inc. Cesium Magnetometer consists of a battery belt, shoulder harness, control unit, non-ferrous horizontal support bar, and 2 cesium magnetometers that can be placed in vertical or horizontal positions. The magnetometers use optical pumping of cesium vapor to measure the magnitude of the earth’s local magnetic field to an accuracy of 0.1 nT while taking a reading every 0.1 s. In essence, the cesium magnetometer is a “reverse NMR” device. The magnetometer is carried by a single operator, and during a continuous survey the magnetometer continuously takes readings while the operator walks. At a normal walking pace a reading is taken approximately every 10 cm along a survey transect. Earth’s local magnetic field Magnetic field of buried object From the data that was collected our team was able to identify 3 possible activity areas and 7 suspected pithouse locations. Figure 1 is a shaded relief plot of 3 survey units that was created using the Kriging gridding method with the projected false Sun set to an altitude of 25 degrees and an azimuthal angle of 90 degrees. Figure 2 is an image plot using false coloring. Pithouses were distinguished by [ fi AUTHORS: K. Faehndrich M. Rogers G. Shear Ithaca College, Physics Department A survey of the entire site was not possible due to topography and surface obstructions such as, mesquite trees, shrubs, and a metal fence surrounding the site. We selected units to overlay predicted pithouse locations, and units were established using laser surveying equipment, while also clearing surface obstructions using axes. Blaze orange, plastic weed-whacker lines to help keep the surveyor on a straight line are run N-S within the grid every 50 cm. A bi-directional survey was conducted by walking north along a transect (shown as red lines in the figure to the left) then moving 1 transect to the East and walking South (shown as blue lines in the figure to the left). Where surface obstructions could not be cleared the data has been blacked out on the image GBRS Local-X Grid Coordinate (m) [subtract 1000 m for Archaeo-Grid] G B R S L o c a l - Y G r i d C o o r d i n a t e ( m ) [ s u b t r a c t 5 0 0 0 m f o r A r c h a e o - G r i d ] GN Shaded Relief Plot Units 21, 22, 23 Image credit: nature.org/wherewework/fieldguide/projectprofiles/gmh.html a spatially small anomaly with a large magnetic signal surrounded by a circular zone of low magnetic contrast. Some magnetic signals that we are interpreting as pithouses were not previously identified as possible pithouses by archaeologists. The central hearths and floors of the pithouses were well defined in the magnetic data but the edges of some pithouses were poorly defined. Magnetic signatures of activity areas proved harder to identify in the magnetic data. We are currently waiting for results of excavations to confirm our interpretation of magnetic data. l i [ t We intend to return to the site and other sites in the area to test our predictive model. The purple circles on the figure below represents Dr. Roth’s prediction of pithouse locations. This map was overlaid on a magnetic map of data we collected. Once the results of the ground-truthing are obtained we can overlay those results onto the Archaeological predictions and our predictive model. A comparative analysis of the predictive models helps us to understand the cesium magnetometer’s capability of identifying features of archaeological interest in this environment. ABSTRACT: Many ground-based remote sensing surveys conducted in the United States are conducted in a contract fashion where completed surveys result in final descriptive, project reports. Rarely are issues of sampling size, image processing, and data analysis addressed in these contract projects. Much of these baseline understandings of ground-based remote sensing surveying have yet to be studied. This poster reports on the ability of a cesium magnetometer survey to record the magnetic signals created by human modification of the landscape at a 1,000-year-old pithouse village site. On going studies are examining the role of transect spacing, the use of image enhancement methods, and the affect of a cesium magnetometer survey to image desired features. Image credit: www.cliffdwellingsmuseum.com/phous.gif 5490 5480 5470 5460 5450 5440 5430 1480 14841488 1492 Acknowledgements: -University of Nevada – Las Vegas -Ithaca College Physics Ford Research Fund -Ithaca College Dana Internship -Ithaca College Faculty Salary