Analyses and Interpretation of Ground Magnetic Data at Sungai Batu, Kedah, Malaysia in Search for Buried Archaeological Remains

Ground magnetic data were acquired, analysed and interpreted for shallow archaeological investigation at Sungai Batu, Lembah Bujang, Kedah, Malaysia. The objective is to locate buried archaeological remains, typically in form of baked clay bricks in the surveyed area. Magnetic field intensity data were acquired using G-856 proton type magnetometer at 1 m by 2 m grid spacing. During the data acquisition, suitable base station was established 50 m away from the study area, to take readings at 1-min interval for diurnal data correction and regional-residual separation. Residual field intensity values obtained were in the range of -25 nT to 177 nT. The values were generally divided into two main classes: low magnetic (< 38 nT), and high magnetic (> 38 nT). The data were gridded and contoured using Oasis Montaj software to obtain the magnetic residual field intensity map. The gridded data were reduced to magnetic equator to shift peaks of anomaly over centres of magnetic source. Automatic gain control filter was thereafter applied to enhance signal in regions of low field variation and to suppress signal in regions with high field variation. The process revealed sharp anomalies interpreted as signatures of baked clay bricks at the western and eastern parts of the area.