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Mosses Which Build Up Limestone

In trickling springs of mountainous regions, and on the limestone rocks of Niagara Falls, and in other localities are found mosses which obtain part of the carbon dioxide (C O2) they require by the decomposition of the bicarbonate of lime [H2 Ca (CO3)2] dissolved in the surrounding water. The mono-carbonate of lime (Ca CO3), which is insoluble in ordinary water, is then precipitated in the form of incrustations upon the leaves and stems of the plants. Gymnostomum curvirostre, Trichostomum tophaceum, Hypnum falcatum, and others which regularly occur in streams arising from springs loaded with bicarbonate of lime [H2 Ca (CO3)2] in solution become completely incrusted with lime, but go on growing at the tips as the older and lower parts imbedded in lime die off. In consequence, the bed of the stream itself becomes calcified and elevated, and, in the course of time, banks of calcareous tufa are formed, which may attain to considerable dimensions. Banks raised in this manner are known which are not less than forty-eight feet in height. To construct them, it is estimated that mosses must have been at work on them for more than 2,000 years.