1913] SNOW—DELAWARE COAST 47 
pratically no middle beach, the summer storm-tides usually 
reaching the bases of the frontal dunes. The succulents character- 
istic of this zone appear, therefore, around the bases and on the 
slopes of these dunes. 
4 2. Dunes.—Outer series—This series is practically fixed from 
the Henlopen Life Saving Station to a similar station at Dewey 
Beach, a distance of five miles. The dunes are held chiefly by 
Ammophila arenaria, with a sprinkling of Cenchrus tribuloides and 
succulents. 
Between these dunes are many passages leading into hollows 
or lakes which are flooded in times of storm. As the beach is 
narrowing, the flooding of these regions occurs more frequently 
than formerly, thus causing a retrogression toward more hydro- 
phytic conditions. The best example of this is the “flooded area”’ 
north of Rehoboth, called in the previous paper ,“‘desert waste,” 
because a large portion of it was at that time bare, damp soil. 
It is reported to be at times “dry with a shining crust,” but in 
July ro911, although the month was a rather dry one, the whole 
area appeared to be under water, thus indicating a greater inflow 
from the sea. At the south edge of this region are to be found 
isolated plants of Mollugo verticillata, Sesuvium maritimum, and 
Spergularia marina (Tissa marina). A second example of flooding 
__ by the sea is presented by Silver Lake, south of Rehoboth. The 
presence of numbers of crabs in this lake indicates frequent addi- 
tions of salt water. This inflow of the sea takes place at a point 
near the south end of the lake where the margin closely approaches 
the tide line. Similar retrogressive movements have been described 
by HARSHBERGER as occurring in northern New Jersey.* 
As was formerly noted, a region of great activity extends from 
a short distance south of the Henlopen Life Saving Station to the 
Henlopen Lighthouse. The large dunes, forming three amphi- 
theaters opening seaward, have moved many feet inland during 
the last ten years. In passing back over alternating pine ridges 
and swamps, they have exposed “‘pine graveyards” and left in 
bo 2h ide 
eee 
Sey ee ee 
oe” 
rane ate rd LN yy ig DE a a Oey cg, tc ee hn Ce Sy ae es ET e setae mS fie Aimy ee Se en ee Ree Cee Pes SET On Sree hy ce BO 
3 Cow es, H. C., The causes of vegetative cycles. Bot. Gaz. 51:161-183. 1911. 
: 4 HARSHBERGER, J. W., The vegetation of salt marshes, and of salt and fresh- 
water ponds of Northern Coastal New Jersey. Proc. Acad. Nat. Sci. Phila. 1909: 373- 
400. figs. I-6. 
