ABSTRACT: Travertine, which is a type of chemical sedimentary rock and is composed of calcium carbonate, has arelatively recent formation age when compared to most rocks. Nevertheless, weathering in travertines maybe quite effective in short time span due to their physical structures and chemical compositions. Despitethe intensive use in building stone market, the weathering of travertine in rock mass scale has not beeninvestigated yet. In this study, the Eskipazar yellow travertine having an intensive usage in travertineindustry in Turkey as well as employed in the construction of Anıtkabir is selected as study material. Theweathering mechanism of the yellow travertines is revealed through observational studies and massmeasurements on exposures with different degrees of weathering in the field. As a consequence of thesestudies, an objective and practical weathering classification is proposed by preparing descriptive criteria.Accordingly, four different weathering classes - fresh, slightly weathered, moderately weathered andhighly weathered - are distinguished for the yellow travertines in rock mass scale. It is thought that the