Using Gradiometric Technique to Prospect Archaeological Features in Tell Al-Deylam, South of Babylon City, Middle of Iraq

Abstract

An extensive vertical magnetic gradiometry survey was carried out over an area spanning 1,188 square meters in the northwestern section of Dilbat; a recently discovered archaeological city within Tell Al-Deylam located approximately 20 km south of Babylon city, so as to reveal the real image of the archaeological features hidden beneath the earth’s surface. The vertical gradiometric survey was done by the Geometrics-G-858 Cesium magnetometer. The gradiometric results showed three clear longitudinal magnetic anomalies in different places on the magnetic contour map. The main anomaly is located on the edge of the northern part of the study area and extends longitudinally in the northwest and southeast direction. This may indicate the presence of the main outer wall, as it extends lengthwise about 30 m, with a width of 3-4 m, and a depth of about 1 m below the surface of the ground, and may contain the main northern gate of the Dilbat Temple. Besides that, this anomaly displayed approximately a high magnetic value of about + 60 nT, which indicates that the wall was built from baked brick composed of clay minerals rich in iron oxides. Furthermore, the magnetic contour map showed two other magnetic anomalies. The first one is located in the western part of the study area and appears perpendicular to the main magnetic anomaly. Meanwhile, the second anomaly occupied the southern part of the study area and is parallel to the main anomaly. The two anomalies showed approximately lower magnetic strength than the outer wall. So, they may represent the remains of the inner room walls built from mud bricks. The thickness of the two supposed walls is about 2.5 m and they are at a depth one meter from the ground. The findings of this method have been a good guide for new excavation, which led to finding the main wall built from fired bricks.