40 THE UNIVERSITY OF OKLAHOMA 



from living mosses to incrusted plants and finally to the compact 

 limestone is a slow development. A second type of travertine, ap- 

 pearing in the form of small overlapping calcareous beds in three 

 approximate rows for each moss stem, — arranged like the leaves 

 of cedar or arbor vitae — is so different that one would suspect it to 

 have been formed about mosses of another species. Such is not 

 the case, but instead, the same species of mosses are incrustd with 

 calcium carbonate but in a slightly different manner. If the mosses, 

 instead of growing in erect tufts on the margin of the falls, grow 

 in the more rapid water and appear on the lower ledges of the 

 falls, the plants are more scattered and bend downward because of 

 the water constantly passing over them. As the calcareous water 

 evaporates, the incrustation slowly thickens about the leaves and 

 stems, keeping pace with development of the plants to within one 

 or two millimeters of the apex. The deposits about the leaves 

 accumulate into little calcareous beads that are finally cemented 

 into a soft mass of travertine. Photographs were made illustrat- 

 ing the gradual transition from living moss plant to soft cavernous 

 limestone ; a stone of a different appearance and formed in a 

 slightly different manner from that of the first type. The plants 

 of the same species of moss, however, serve as nuclei in the forma- 

 tion of both types of travertine. 



PLATANUS OCCIDENTALIS 

 C. N. Gould, 1916. 



Platanus occidentalism the American plane tree, or button-wood, 

 popularly known as sycamore, is one of the largest of the trees 

 of North America. It may be classed among the semi-hydrophytes, 

 or water-loving plants, in that in its wild state it almost always 

 grows along stream courses and near water. The broad, graceful, 

 branching form, and large leaves, render it an excellent shade and 

 ornamental tree, and it is frequently transplanted to the uplands, 

 particularly along city streets, where it grows rapidly and often 

 attains considerable size. 



The sycamore is not generally considered a useful tree. It 

 never finds a place among the listed species of important North 

 American hardwoods. It rots easily, warps badly, and is rarely 

 used for lumber. About the only use to which it is put is for fire- 

 wood, and even as fuel, it is by no means as satisfactory as a 

 dozen other woods. In selecting timber for firewood the farmer 



