A pilot study of the petrified forests of Lesvos Island and Kastoria and the use of a non-destructive method for identifying and measuring soluble salts contained in material found on both sites are presented here. This method is based on the application of neutral paper pulps impregnated in deionized water on some trunks. The study includes monitoring environmental conditions, macroscopic examination and mineralogical study of fossils. Based on climatological data, the period when frost action and temperature variations occur was determined. The results indicate that, on Lesvos Island, there is an extensive problem of deterioration due both to the crystallization of soluble salts and frost action during the winter. At the Kastoria site there is deterioration caused by frost action during the months of December to February, the crystallization of soluble salts and biological depositions. -- SCMRE