116 ILLINOIS ACADEMY OF SCIENCE 
320 feet above the lake, about 100 feet being sand (Fig. 2A). 
This dune area is about half a mile long and about half that 
width, and has recently been mapped and described by Water- 
man’. The upper stratum of morainic material is largely com- 
posed of boulder clay, giving when eroded a number of “razor- 
back” cliffs. The dunes have been fixed and forested but 
through them has cut a complex of wind-sweeps ending in a 
semicircular blow-out popularly known as “The Crater” (Fig. 
2B). The wind-sweep throughout the greater part of its chan- 
nel has cut quite through the sand and has exposed the surface 
of the morainic plateau. The sand of which this perched dune 
is composed may well have been derived from the waters of the 
former Lake Algonquin, although there is nothing to show that 
they are not of terrestrial origin. In this connection it may be 
recalled that the moraine upon which the dunes are perched are 
at least 150 feet above the supposed level of Lake Algonquin or 
of the Nipissing Great Lakes. 
A second example of even more remarkable perching is 
found four miles north of Empire in the Sleeping Bear dunes. 
Here the morainic substratum is in the form of a kame-like 
ridge with its long axis parallel to the Lake Michigan shore 
and its fiat top about 400 feet above the lake. At the north and 
east of this plateau the gravelly surface is much lower, while 
an east-west section through the ridge just north of “The Bear” 
shows that a peak (Fig. 3A) of gravel near the eastern side 
projects above the sand which has been swept from the plateau 
and is moving towards the east. That the greater part of this 
plateau was formerly well covered with perched dunes is 
evidenced by the great banks of sand on the west side where 
they present a great advancing lee front over a mile long with 
a maximum height of over 300 feet (Fig. 3A). Upon this wind 
swept plateau the most conspicuous dune remnant, perched on 
the edge of the shore cliff, is the isolated mound some 90 feet 
high and four times as broad, known as the “Sleeping Bear” 
(Fig. 3B). The north and east slopes are still well covered with 
the remnants of a mesophytic forest in which Thuja occident- 
alis, Sorbus americana, Acer saccharum and Tsuga canadensis 
2Waterman, W. G. Ecology of Northern Michigan dunes: Crystal Lake 
Bar region. Rep. Mich. Acad. Sci. 19: 197-207. 1917. 
