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Unltod St¡toc DopaÉmcnt o,f Agrlcullurc ONRCS Natural Resources Conservation Service National Soil Survey Center Federal Building, Room 152 100 Centennial Mall North Phone: (402) 437-549e Lincoln. NE 68508-3866 FAX: (402) 437-5336 SUBJECT: MGT - Trip Report - Geophysical Training and April12,2013 Field Assistance TO: Homer L. Wilkes File Code: 330-20-7 State Conservationist, NRCS Jackson, Mississippi Purpose: To provide training and technical assistance in the use of electromagnetic induction (EMI) and ground-penetrating radar (GPR) in Yazoo County, Mississippi, while assessing soil properties and cultural resources at a registered historical archaeological site (Lake GeorgeÆIolly Bluff Site - 22Y2557). Participants: David Clay, Engineer (Retired), NRCS, Wilkesboro, NC James Curtis, Assistant State Soil Scientist, NRCS, Jackson, MS Rachel Stout-Evans, MLRA Project Leader, NRCS, Metcalfe, MS Cliff Jenkins, Cultural Resources Specialist, NRCS, Jackson, MS Delaney Johnson, State Soil Scientist, NRCS, Jackson, MS Wes Tuttle, Soil Scientist (Geophysical), NRCS, NSSC, Wilkesboro, NC Richard Vaught, MLRA Project Leader, NRCS, Glenwood, AR Activities: All field and office activities were completed on January 25-28,2013. Summary: 1. All participants were given the opportunity to operate, complete field surveys, and evaluate the use of the EM38 meter for soil survey investigations. 2. Electromagnetic induction (EMI) techniques can be used beneficially in the Mississippi Delta Region to show changes in soil physical properties across the landscapes, as demonstrated at the archaeological site (Lake George/flolly Bluff Site -22Y2557). The tools worked very well in predicting textural changes across the survey area. Higher apparent conductivity was associated with increased clay and moisture in the soil profile. Soil borings in areas of higher apparent conductivity revealed an increase in clay and moisture. Areas with dominantly coarser soil textures were associated with lower apparent conductivity. The soils stafß in MO 6 and MO 7 are planning on utilizing the Geonics EM38 meter to further evaluate soil map units and changes in soil properties. Additional training will be provided by the NSSC staff as requested. Ground-penetrating radar (GPR) training was provided to Richard Vaught, MLRA Project Leader, NRCS, Glenwood, Arkansas. GPR surveys were conducted at the site to assess the tool's effectiveness in soils dominated by silt and clay. High GPR signal attenuation rates were observed in radar Helping People Help the Land An Eqsal Opportunlty Provldor end Employor V/ilkes, Page2 records collected at the site and the effective depth of observation was severely restricted. The use of EMI techniques was a better choice for making interpretations at the site. 4. In areas not influenced by episodes of mound building and soil movement during earlier inhabitation at the site (minimally disturbed soils), the observed EM38 spatial conductivity patterns were thought to be associated with the orientation of natural "ridge and swale" landform patterns associated with the major river systems in the area. The directional orientation of the spatial patterns was observed in the USDA, NRCS V/eb Soil Survey and aerial photos of the area and closely fit the "ridge and swale" landform patterns. It was a pleasure for Wes Tuttle to work again in Mississippi with members of your fine staff. il/Ltn,t ¿/t/16, b¡.vn R. HoovER Acting Director National Soil Survey Center Attachment (Technical Report) cc: Ellis C. Benham, Research Soil Scientist, Soil Survey Research & Laboratory, NSSC, MS 41, NRCS, Lincoln, NE Reed W. Cripps, Acting State Soil Scientist, NRCS, Little Rock, AR James L. Curtis, Assistant State Soil Scientist, NRCS, Jackson, MS James A. Doolittle, Research Soil Scientist, Soil Survey Research & Laboratory, NSSC, NRCS, Newtown Square, PA Rachel M. Stout-Evans, MLRA Project Leader, NRCS, Metcalfe, MS James C. Jenkins, Cul¡¡ral Resources Specialist, NRCS, Jackson, MS Delaney Johnson, State Soil Scientist, NRCS, Jackson, MS David Kingsbury, Soil Survey Regional Director, NRCS, Morgantown, WV Charles Love, Soil Survey Regional Director, NRCS, Auburn, AL John W. Tuttle, Soil Scientist, Soil Survey Research & Laboratory, NSSC, NRCS, Wilkesboro, NC Richard L. Vaught, MLRA Project Leader, NRCS, Glenwood, AR LarryT. West, National Leader, Soil Survey Research & Laboratory, NSSC, MS 41, NRCS, Lincoln, NE Linda A. Kruger. Secretary, Soil Survey Research & Laboratory, NSSC, MS 41, NRCS, Lincoln, NE Electromagnetic Induction Assistance and Training Technical Report Yazoo County, MS Wes Tuttle January 25-28,2013 Purpose: To provide training and technical assistance in the use of electromagnetic induction (EMI) and ground-penetrating radar (GPR) inYazoo County, MS, while assessing soil properties and cultural resources at a registered historical archaeological site (Lake GeorgeÆIolly Bluff Site - 22Y2557). It is hoped that in addition to training that geophysical methods can provide additional insight and a better assessment of earlier inhabitation by Native Americans at the site. Equipment: Geonics Limited manufactures the EM38 meter. This meter is portable and requires only one person to operate. No ground contact is required with this meter. McNeill (1980) and Geonics Limited (1998) have described principles of operation for the EM38 meter. Lateral resolution is approximately equal to its intercoil spacing. The EM38 meter has a 1 m intercoil spacing and operates at a frequency of 14,600 Hz. When placed on the soil surface, this instrument has a theoretical penetration depth of about 0.75 and 1.5 m in the horizontal and vertical dipole orientations, respectively (Geonics Limited, 1998). Values of apparent conductivity are expressed in millisiemens per meter (mS/m). An Allegro field computer was used in combination with the EM 38 meter to record and store EMI data. The field computer is keypad operated and measurements can either be automatically or manually triggered. EMI data was geo-referenced with a Trimble AG-l l4 GPS receiver and a GM-210 GPS receiver manufactured by HOLUX Technology, lnc. To help summarize the results of this study, the SURFER for Windows (version 8.0) developed by Golden Software, lnc., was used to construct two-dimensional simulations. Grids were created using kriging methods with an octant search. The radar unit is the TerraSlRch SIR (Subsurface lnterface Radar) System-3000, manufactured by Geophysical Survey Systems, lnc.' Morey (1974), Doolittle (1987), and Daniels (1996) have discussed the use and operation of GPR. The SIR System-3000 consists of a digital control unit (DC-3000) with keypad, color SVGA video screen, and connector panel. A 10.8-volt Lithium-ion rechargeable battery powers the system. This unit is bacþack portable and, with an antenna, requires two people to operate. The antenna used in this study has a center frequency of 200 MHz. A Garmin GPS Map 76 receiver (with a CSI Radio Beacon receiver, antenna, and accessories that are fitted to a bacþack) was used in combination with the SIR-3000 radar unit to collect radar records. The RADAN for Windows (version 6.6, version 7.0) software.program was used by the NRCS staff to process the radar records (Geophysical Survey Systems, Inc,).' Processing typically includes color transformation, marker editing, surface normalization, time-zero adjustment and range gain adjustments. Electromagnetic Induction: Electromagnetic induction is a noninvasive geophysical tool that can be used for soil and site investigations. Advantages of EMI are its portability, speed of operation, flexible observation depths, and moderate resolution of subsurface features. Results of EMI surveys are interpretable in the field. This I Manufacturer's names are provided for specific information; use does not constitute endorsement. geophysical method can provide in a relatively short time the large number of observations that are needed to comprehensively cover sites. Maps prepared from correctly interpreted EMI data provide the basis for assessing site conditions, planning further investigations, and locating sampling or monitoring sites. Electromagnetic induction uses electromagnetic energy to measure the apparent conductivity of earthen materials. Apparent conductivity is a weighted, average conductivity measurement for a column of earthen materials to a specific depth (Greenhouse and Slaine, 1983). Variations in apparent conductivity are caused by changes in the electrical conductivity of earthen materials. The electrical conductivity of soils is influenced by the type and concentration of ions in solution, volumetric water content, temperature and phase of the soil water, and amount and type of clays in the soil matrix (McNeill, 1980). The apparent conductivity of soils increases with increases in soluble salts, water, and clay contents (Kachanoski et al., 1988; Rhoades et a1.,1976\. Electromagnetic induction measures vertical and lateral variations in apparent electrical conductivity. Values of apparent conductivity are seldom diagnostic in themselves. However, relative values and lateral and vertical variations in apparent conductivity can be used to infer changes in soils and soil properties. lnterpretations are based on the identification of spatial pattems within data sets. To assist interpretations, computer simulations of EMI data are normally used. To verify interpretations, ground-truth measurements are required. Ground-Penetrating Radar (GPR) : Ground-penetrating radar is a time scaled system.