Environmental impacts: Weathering factors, mechanism and forms affected the stone decaying in Petra

The decay of stones in a natural environment is governed by extrinsic and intrinsic factors. Petra is exposed for centuries to the severe climatic conditions especially temperature (T), total monthly rainfall (TMR) and relative humidity (RH). In this regard, there are negative effects that result from these climatic elements on stone; which affect or are based on the chemical characteristics and physio-mechanical properties of the Petra rocks. The aim of this work is to determine the chemical and mineralogical characteristics including the morphological features which affect the behavior of stones in various environments using valuation techniques such as XRD, PM, Stereo M and SEM. The results proved that the stone was highly affected by two different deterioration mechanisms. The 1st one concerning physical mechanism and the 2nd one is regarding chemical deterioration. Both of them have led to some deterioration forms such as deep cracking, scaling, exfoliation and crumbling due mainly to the heating and cooling alternative cycles as well as frost action. In addition to salt crystallization and powder steadily off. It also show that most of the un-sheltered monuments were severely affected by the freezing and thawing actions, which is need to be a target in a special article to study their different effects. These activities in Petra are the subject of this study which also recommends the suitable materials and methods for preserving these valuable sites.