a Sn 5-5 cp iat a Wilk hens 
SS SS iy ee iene eee Cea er tine ete ne Se pS kp eee 47 
a Reece fa spe he eee eS) 8 SR pe a ie sek a ee eee 
Bee hab at een ea das ee : 
epee Ceres Suit ReMi 
1913] SNOW—DELAWARE COAST 55 
thus extending the coast northward with the development of Cape 
Henlopen. This erosion stage is still in progress. 
~IV. Summary 
1. Ten years is too brief a period in which to show any consider- 
able change in plant associations, even in so active a region as that 
of the dunes. | 
2. Progressive changes were observed: (a) advancement of 
the Hudsonia complex toward the heath; (b) advancement of the 
heath toward the thicket; (c) drying of isolated swamps and lakes; 
(d) fixation of the ‘‘canal dune.” 
3. Retrogressive changes were noted: (a) recession of the coast, 
resulting in more frequent flooding of certain regions, thus continu- 
ing or increasing their hydrophytic character; (b) movement of 
active dunes over the forest. 
4. The character and position of the sand-clay ledge suggests 
that it may have been an ancient sea-cliff. 
5. The presence of a ledge of peat in the beach indicates the 
location of a former swamp. 
6. This swamp was probably due to the presence of an ancient 
bar inclosing a lagoon. 
7. The present erosion of the coast indicates that this bar with 
its dunes was moved inland over the swamp, while portions of the 
beach material were carried northward to form the hook. 
8. This process of erosion is still in progress. 
DEPARTMENT OF BOTANY 
WELLESLEY COLLEGE 
