— 26 — 
into the air and only a comparatively small amount of free carbon dioxide or 
the carbon dioxide derived from the bicarbonates in solution is used by the 
mosses during the process of photosynthesis. The change of equilibrium, in- 
duced ^by the loss of carbon dioxide from the mineral water, is followed by a 
separation of calcium carbonate in such a manner as to place a white crystalline 
covering on the outer surfaces of the plants. The transition from the moss 
plant to incrustation, Plate XV, fig. i, and finally to compact limestone, Plate 
XV, fig. 2, is a very slow development. The moss leaves and stems with their 
initial covering of crystals, Plate XV, fig. i, serve as centers for the continued 
formation of travertine. In the interstices of this coral-like mass, the gradual 
accumulation of calcite gives rise to a hard but cavernous limestone. The 
fractured, longitudinal surfaces of the hardened travertine often show impres- 
sions or casts which indicate the position of the original moss leaves. Cross 
sections of the same travertine, Plate XV, fig. 3, reveal small and regular canals 
which have changed but little since the decay of the incrusted moss stems. 
By the action of the same physical and chemical agents described above, 
another type of travertine is produced if the moss Didymodon happens to grow 
suspended from the projecting ledges of waterfalls. Under these conditions 
the incrustations follow the development of the moss to within a few m.m. of 
the growing tips, transforming the leaves into rounded calcareous beads, Plate 
XV, fig. 4, which are finally cemented together into a soft mass of travertine. 
Fractured longitudinal surfaces of the hardened travertine, as shown in fig. 6, 
presents the arrangement of calcareous beads, which in all essentials are like 
the rounded masses of calcium carbonate as represented in fig. 4. Thus the 
type of travertine formed by the moss Didymodon depends largely on the orig- 
inal position of the growing plants. If the moss appears in erect tufts, Plate 
XVI, fig. 1, on the exposed surfaces of rapids, the travertine formed is like that 
shown in Plate XV, fig. 2; but if the plants grow suspended from overhanging 
ledges of waterfalls, Plate XVI, fig. 2, the travertine is like that represented in 
Plate XV, fig. 6. 
In the newly formed cavernous deposits, water mosses, and filamentous and 
unicellular algae are usually present. The most active deposition, 3 to 5 inches 
during a single summer, takes place in the presence of Vaucheria. But the de- 
velopment of travertine about moss plants will not exceed one inch per year 
under the most favorable circumstances; for as soon as the interior of certain 
tufts have hardened, the water currents will be diverted through other less re- 
sistant channels. The various streamlets shift from place to place on account 
of the unequal development and incrusting of the mosses. The growth of each 
separate moss tuft is intermittent. 
The mosses, however, are not the primary factors in the building of the 
travertine falls. If boulders collect in the channels so as to form a series of 
rapids, then the water mosses growing in the shallow currents will aid in the 
cementing of the boulders into a conglomerate dam. In addition, the traver- 
tine deposits have modified the appearance of practically all of the natural falls 
of the Arbuckle Mountains. On Honey Creek at the present site of Turner 
