Anastylosis of Apsidal Roof Engineering for Ecclesiae of Hawrān during Late Antiquity: Case of Julianos Church in Umm el-Jimal, Jordan

Abstract

Umm el-Jimal, located in Hawrān of Late Antiquity, is well-known for the use of volcanic-based building materials; mainly basalt stone and scoria. Structural attributes of these two materials are important for examining potential roofing system(s) that could have been used for the semi-circular apse of Julianos Church in Umm el-Jimal. Since the roof is demolished nowadays, the study examines two interpretive theories presented in literature: ‘vault roof’ as put forward by Professor Howard Butler in 1913 and ‘corbelled flat roof’ as suggested by Corbett and Reynolds in 1957. A third theory is also introduced in this study, based on available archaeological remains, relevant cases, and religious and scientific premises. It advocates a ‘composite system’ of corbelled relieving diaphragms and non-load-bearing vaulted structure to generate a box-like buttressing apse. The composite system can operate interactively to resist static loads and dynamic seismic forces. Builders of Hawrān should have introduced novel engineering of their ecclesiastical architecture that differs from its ‘classical’ counterpart. Contemporary conservators can respectively consider these theories in their attempts to salvage the alarmingly vanishing ecclesiae of Hawrān.