Lithology and the distribution of Early Roman-era tombs in Jerusalem’s necropolis

Abstract

During the last 150 years, various archaeological excavations and surveys revealed approximately 900 rock-cut tombs in the extensive necropolis surrounding ancient Jerusalem, dated to the late Hellenistic and Early Roman periods. The research goals are to examine the spatial distribution of these tombs in relation to the lithological units and rock hardness and to examine the diverse methods by which the ancient masons solved various lithological defects they encountered during the tomb excavation. We used field observations and Schmidt hammer tests to determine the rock hardness and the lithological properties. Our study demonstrates that the substrate played a crucial role in the establishment of the city and residents’ living conditions and that the presence or absence of caves in certain areas can be explained lithologically. Most tombs found west of the city were excavated in the Weradim Formation (13.7%); those found north of the city were mainly hewn into the well-bedded Nezer Formation (20.7%); and the tombs hewn east or south of the ancient city mainly met the soft Menuḥa Formation (56%). Excavating in the hard limestone of the Shivta Formation required high levels of effort and funding and, therefore, the number of tombs is limited (3%). In some cases, owners of estates located in soft lithologies granted burial rights to additional families, as proved by the large number of tombs and the clusters of burial systems in the Menuḥa Formation. Rock surfaces are mostly decayed by chemical dissolution, enhanced by structural fissures in the rock. Condensation corrosion and excess moisture were observed on the ceilings of some structures, along with bio-erosion. Two types of defects are common in the local rock: (a) major defects, endangering the stability of the rock-cut chamber that required complementary building with ashlar stones and (b) superficial defects that required only aesthetic solutions.