1920] TAYLOR—SUCCESSION OF MOSSES 45 1 



with various species of trees and shrubs, such as Thuja occidentalism 

 Juniperus communis, and Shepherdia canadensis. On such stab- 

 ilized bluffs, as well as in. the mesophytic ravines, mosses form a 

 conspicuous part of the ground flora. At other points north of 

 Glencoe old dune formations are being eroded. The dune associa- 



much 



ma 



the west shore. 



At the south end of Lake Michigan is an extensive sand dune 

 formation reaching southward for some distance. The finer par- 



w 



. tides of the material eroded on the west shore are carried by the 

 water currents toward the south and there washed up on the beach. 

 The prevailing winds blowing from the lake catch up this fine sand 

 as it becomes dry and carry it farther inland, thus continuing year 

 after year the process of dune building (3). At almost any point 

 which has been left undisturbed by man may be found all stages, 

 from the bare foredune, through the series of cottonwood, pine, 

 early oak, and the well established mixed oak dune formations. 

 At Miller, Indiana, where a part of this work was carried on, the 

 pine dunes are especially well illustrated to the south and east of 

 the Grand Calumet River. This stream, which rises in eastern 

 Indiana and flows almost directly west as the Little Calumet, 

 makes an abrupt curve south of Calumet Lake. It formerly 

 flowed eastward as the Grand Calumet, in a course nearly parallel 

 with that of the Little Calumet, to its outlet into Lake Michigan 

 north of Miller. Later, sand dunes began to form across the mouth, 

 and the stream, being extremely sluggish, was not able to remove 

 the accumulating deposit and was forced to find a new outlet, its 

 present mouth near South Chicago, thus following the path of least 

 resistance. The Grand Calumet now remains as a nearly stagnant 

 body of water which is rapidly filling up with typical pond vegetation. 

 The dune slopes south and east of this part of the river form one 

 of the best moss habitats to be found in the dune complex. Much 

 of the natural flora near the lake and along both banks of the 

 river is being destroyed by the building of cottages. The level of 

 the water in the Calumet has been raised by a dam recently built 

 across the stream farther west. This has not only flooded the low 



