194 BOTANICAL GAZETTE waren 
the situation. Ifthere is a sufficient amount of sand still remain- 
ing, the once stationary dune begins to move, not bodily, of 
course, but none the less steadily and surely. The sand is swept 
up the low gradient of the windward side, deposited at the crest, 
and carried down the steep leeward slope by gravitation. In 
this manner successive parallel layers of the windward slope are 
carried over the crest, and the dune as a whole advances inland. 
The simple life-history just outlined is the exception, not the 
rule. Much more commonly the sand is scattered in many 
directions, collecting wherever new lodging places can be found. 
These processes of deposition and removal, dune formation and 
dune destruction, are constantly going on with seeming lawless- 
ness. However, in the district as a whole the sand is constantly 
increasing in quantity, whatever may be true of the individual 
dunes here and there. The outcome is certain to be a wander- 
ing dune in the process of time, unless the actions of the wind 
and wave are checked. Because of the complexity of the com 
ditions when the movement across the country becomes a col: 
spicuous fact, it seems well to apply the term dune-complex © 
the totality of topographic forms which make up the movilg 
landscape as a whole. 
2. Physical and biological features of the dune-complex. 
It will not be necessary to trace farther the changes involved 
in the transformation of simple beach dunes into a dune-com 
plex, although the coast of Lake Michigan shows all of the inte! 
vening stages. Inasmuch as a single dune-complex illustrates 
almost all conceivable conditions of a dune’s life-history, 4 
ful description of a typical dune-complex will involve all of the 
essential points. The dune-complex is best developed at Gis 
Haven, Mich., and Dune Park, Ind. All of the essential eee 
are present in both areas, though developed on a grander 
at Glen Haven. The Dune Park area has been most careful!) 
studied, and most of my photographs were taken there. as 
The dune-complex is a restless maze. It is a maze gor 
all things that a dune ever does are accomplished there. Wh 
