Travertine is a sedimentary limestone rock of chemical, widely used in construction, particularly in Rome, since I millennium BC.
The difference between the deposit of limestone type and spongy travertine bench is substantially different from the geological formation of the soil: the limestone is one of the most frequent deposits in kind being produced by the precipitation of calcium carbonate dissolved in water.
An environment in which the lime solution has had time to stagnate and sedimentation in a low-lying, near enough to the surface by going through cycles of evaporation and re-submersion, little disturbed by water currents or springs, is the right environment for formation of travertine.