AbstractIn situ measurements were performed on the travertine-encrusted mossesCratoneuron commutatumvar.commutatumandEucladium verticillatumto obtain estimates of calcium carbonate deposition through photosynthesis, evaporation and carbon dioxide evasion. It was estimated that for both species, between 6 and 12% of the carbonate was deposited through photosynthesis, 10–20% through evaporation and the remaining 70–80% through gas evasion.