THE IMPACT OF THE CLIMATIC CONDITIONS ON THE DECAYING OF JORDANIAN BASALT AT UMM QEIS: EXFOLIATION AS A MAJOR DETERIORATION SYMPTOM

Abstract

Climatic conditions (temperature, relative humidity, wind blowing and rainfall) are the main factor of deterioration affecting the archaeological building in Jordan. The an‐ nual averages of climatic elements in the Umm Qeis area during the last 30 years are 15.49 Co temperature, 24.63% relative humidity, 283 mm rainfall and 16.63 knots for the wind speed. These factors represent some of the most serious factors affecting the deterioration cycles of building materials in general and archaeological materials in particular. This study investigates the effect of climatic conditions on the acceleration of weathering processes in Jordan, focusing on the exfoliation as a major deterioration symptom affecting basaltic blocks used in western theater of Umm Qeis archaeo‐ logical site. The techniques used in this study include Digital Caliper, EDX, XRD, Po‐ larized microscopy and SEM. The results have shown that the samples suffer from several deterioration factors that lead to severe deterioration forms through different mechanisms. These forms include exfoliation, material loss, mineral weathering, crust formation and crystallization of soluble salts. Exfoliation form was divided into 4 categories according to the rate of exfoliation grades and the thickness of exfoliated layers: Complete, High, Moderate and Slight. On the other hand, the basalt artifacts in the study area have been affected by other aggressive factors of damaging mechanism such as thermal dilatation, ice pressure, vibration, microbiological infection. All of these dete‐ rioration factors lead to a breakdown in its essential components and create different weathering products such as salts and some loosen decay products.