218 BOTANICAL GAZETTE [MARCH 
meadow swamp. It is followed by Alnus incana, which at first is 
pure, but farther back is found mixed with other shrubs: Cornus 
stolonifera Michx. (red osier dogwood) and Viburnum pauciflorum 
Raf. (high bush cranberry). With these come the invaders from 
the forest, Fraxinus nigra Marsh (black ash) being usually the first 
arrival. Burned stumps indicate that there was once an extensive 
development of swamp 
forest along the east 
side of the delta, in 
which Thuja was the 
important tree. 
The stream which 
winds through the 
swamp is 6-10 m. wide 
and o.3-1m. deep. Its 
channel is constantly 
changing by reason of 
its own undermining 
and depositional activ- 
ity. Near the outer 
edge of the marsh it 
crosses the belt of 
sedges. Farther back 
it is bordered by vari- 
ous societies. Where it 
cuts into the grass- 
covered areas erosion 
by undermining is going 
on, and a section of peat 
sometimes 0.6 m. in 
height is exposed. For 
considerable distances shrubs are also being undermined, and at 
one point the stream in its meandering has invaded the area of 
former swamp forest and has caused the overthrow of many trees. 
The material eroded from the banks is deposited where the current 
slackens, and in such places the normal succession of plant stages 
is in progress; aquatics first, followed by a sedge mat when the 
McCargoe’s Cove 
vvvvV\I 
b v ' 
vv 
ty 
Upland 
CARN DD, 
Wy 
Fic. 50.—Sketch map of the delta at the head of 
McCargoe’s Cove. 
