1899] DUNE FLORAS OF LAKE MICHIGAN 103 
Active dune formation is conspicuous on projecting points of 
land as well as at the mouths of rivers; for example, active dunes 
are to be found on Little Point Sable, south of Pentwater, and 
Big Point Sable, north of Ludington. At many points along 
the coast the winds are breaking through the fringe of estab- 
lished dunes, so that the older dunes may be said to have started 
into activity again or to have become rejuvenated. In summa- 
tion concerning the area between St. Joseph and Frankfort, it 
may be said that the influence of northwest and southwest winds 
in dune formation is nearly equal. Indeed, the two winds com- 
monly work together to produce a composite result, so that the 
winds sweep and the dunes advance, as a rule, from west to east. 
In northern Michigan, between Frankfort and Glen Haven, 
and alsoon North Manitou island, most of the dunes are perched 
high up on bluffs of clay or gravel. The bluffs are steep and 
approach the water’s edge, varying in height from nothing up 
to more than 120 meters. Dunes are to be found upon the tops 
of the very highest of these bluffs in the district south of Glen 
Haven. These perched dunes are almost wholly established, 
and it seems as if their formation took place years ago when the 
lake was perhaps at a higher level. The most remarkable dune 
formation along the entire coast of Lake Michigan is to be found 
on Sleeping Bear point, just south of Glen Haven. The point 
Stretches out into the lake, and is constantly growing to the 
northward and eastward by reason of the joint action of waves 
and winds. The point proper is geologically quite young, and, 
apart from the present beach and stationary beach dunes, is cov- 
ered by an immense and active dune complex. At many points 
the wind has scooped out great hollows in the complex, expos- 
Wess the gravel of a former beach. The advance of the dunes in 
this area is chiefly eastward, the exposed fossil beaches being 
chiefly toward the west. Two or three kilometers southward 
from the point, the region of low active dunes passes somewhat 
suddenly into an immense flat-topped hill, rising abruptly from 
the lake like a mesa or terrace. The height of the dunes on the 
POint is seldom greater than 30 to 45 meters, while this peculiar 
