Cultural Resource Analysts, Inc.: Consulting Services for the Study of Earth and Man

Geophysical Survey of Cahokia Mounds, near St. Louis, Missouri

In May 2003, Dr. Berle Clay, geophysical specialist for CRAI, served as instructor in the National Park Service workshop, Current Archaeological Prospection Advances for Non-destructive Investigations in the 21st Century. Held this year at the World Heritage archaeological site, Cahokia Mounds near St. Louis, this was an opportunity to use and demonstrate the latest in magnetic and electromagnetic survey instrumentation on a highly significant archaeological site. Dr. Clay was assisted by Jon Kerr, Grant Day, Brian King, and Andrew Martin, all of CRAI, in collecting data sets for the workshop and instructing the participants. In Figure 1, Jon Kerr runs the Geonics EM38 earth conductivity meter in data collecting on the Ramey Tract in the shadow of Monk's Mound, the largest earthen mound in North America north of Mexico. In Figure 2 he runs the newest addition to CRAI instrumentation, a Geoscan Research FM 256 fluxgate gradiometer duplexed with a FM 36 gradiometer. In combination, the two gradiometers provide high-density magnetic information (Figure 3) and cover the ground at twice the speed. The duplexer, representing its first use in the Western Hemisphere, is an example of our continuing commitment to bringing geophysical survey technology to the archaeological world at both an affordable cost, and a more useful level of resolution.