296 BOTANICAL GAZETTE [| MAY 
side of the lake, and the southern shore of Lake Superior in the 
neighborhood of Marquette, Michigan, offer exceptionally good 
fields for a study of the stages in the life history of the forest 
societies. North Manitou island, in general, consists of a clay 
core covered over and added to by sand formations, principally 
beach and dune. So complex are these in the interior that it is 
difficult to trace any definite time relations, and no attempt was 
made to do this. On the south and southeast ends of the island 
however, where the beaches and dunes are in the process of for- 
mation, it is not so difficult to discover the time relations. The 
northern portion of Beaver island and the mainland in the 
vicinity of Charlevoix, Michigan, have similar formations. On 
the southern shore of Lake Superior, while the beaches are pres- 
ent, the dunes are for the most part absent. The beach and 
dune societies have been so thoroughly studied by Cowles that 
attention need only be called to the points in his work essential 
to the understanding of the various stages in the life history of 
the forest of these regions. 
THE LOWER BEACH. The lower beach is defined as that por- 
tion washed by the summer waves. There are a number of fac- 
tors here, any one of which may exclude vegetation. Since the 
beach is the shore drift in transit, the very movement of the 
sand or pebbles may prevent plant life. The mechanical wash 
of the waves would uproot any plants that had obtained a foot- 
hold. Again, the border between the land and water presents 
at one time a xerophytic and perhaps the next moment a 
hydrophytic habitat. However, in protected places, or where 
the water is shallow for a distance from the shore, the breaker 
line thus being distant from the shore, a condition is obtained 
which may bring into existence a hydrophytic society. Wher- 
ever sand is accumulating along the shores in the region under 
discussion, the lower beach is prominent. With a further reces- 
sion of the lake it may pass into the middle beach. It is con- 
sidered, therefore, the first stage in the life history of the forest, 
for by the action of the waves a soil is made, the first requisite 
for any forest society. 

