North American Database of Archaeological Geophysics
North American Database of Archaeological Geophysics
Graphic/Image:
Project Name: Effigy Mounds, IA (5);
Reference: Watters, M.S. (1999). Geophysical Work Conducted with the Geometrics G858 Cesium Vapor Magnetometer at Effigy Mounds National Monument, IA. As part of the U.S. National Park Service Workshop: "Recent Advances in Archeological Prospection Techniques," May 10-14, 1999. Submitted to the Midwest Archeological Center, U.S. National Park Service, Lincoln, Nebraska.
Magnetic gradient of the Little Bear Mound. The large yellow and two large blue areas in the top image are iron posts (the top blue area is a geological marker) in the ground. We can see the strong magnetic influence iron has on the sensitive magnetometer. The contrast of the mound soils themselves to the surrounding site soils is easy to see, and in fact, the slight outline visible (mainly with green/purple/blue) around most of the mound (well defined at the back end of the bear, rounding up to the bear's back) may be revealing the sand outline around the mound.