1899] DUNE FLORAS OF LAKE MICHIGAN <7 
Anemone multiida. The flora of this isolated island beach is 
remarkably prolific; scarcely a single upper beach type is absent. 
It is obvious that the means of plant dispersal are so uniformly 
successful, that almost an entire flora may be transported to a 
newly formed island within a few years. 
One other common feature of upper beaches should be men- 
tioned. As noted above, there are irregularities in the slope of 
the beach often resulting in depressions which reach below the. 
water level. Such depressions may be called beach pools and of 
course have a hydrophytic flora; this flora, however, is not the 
flora of a hydrophytic beach. Beach pools are relatively pro- 
tected from the action of winds and waves; the chief difference 
from a hydrophytic beach is that the latter is washed by the fresh 
waters of the lake, while the beach pools are far less constantly 
Supplied with fresh water. The conditions in the latter approach 
Somewhat those of the ill-drained inland sloughs between the 
‘andy ridges, By far the most characteristic plant about the 
ie margins is Juncus Balticus littoralis; this species is more 
oor than most of its genus, and often creeps well up on 
a nee licupper beach. TZviglochin maritima, Potentilla Anser- 
nd several species of Salix also occur about the margins of 
the pools, 
4. Fossil beaches. 
wae “ heahadg dunes are superposed upon the beach, por- 
sand, a sh each aay remain unoccupied by the wind-blown 
has — as islands in a sea of dunes. Or a beach which 
exposing oo by the dune-complex may later be uncovered, 
case these an = and shingle of an ancient shore. In any 
the “lent or fossil beaches, separated as they are from 
“ Present beach by dunes, are more highly protected from the 
Wind than the beach gnly Pr oo 
©cold winds | €s which have been previously described. 
the gradual sl S ‘ose little of their energy while sweeping up 
siderably tae OF si ordinary beach, but their force is con- 
e elses y a line of dunes. Fossil beaches which have 
‘0 such a limit y the dune complex occur at Dune Park, but 
ed extent that a typical flora is not developed. 
