1913] COOPER—ISLE ROYALE 199 
sidence of the lake level the 
bar at the exposed southwest 
end emerged and became a 
beach connecting the two 
ridges, which now inclosed a 
sheltered bay. Into this con- 
siderable sediment was still 
being carried by waves and 
currents. As the lake level 
continued to fall, the more 
slowly building bar across the 
sheltered northeast end of the 
harbor emerged, and the bay 
was now an inland lake. Itis 
probable that the height of 
both beaches has been in- 
creased since their emergence 
: through the agency of storm 
a waves. The physiographic 
history of the habitat is thus 
concluded. Its likeness to 
Amygdaloid Island will be at 
- once evident. At Amygdaloid 
4 Lake we find the beginnings 
of the bog vegetation; Rasp- 
berry Island shows its culmi- 
nation, in the sense that at 
this stage the open water has 
disappeared, and all the bog 
societies are present and at 
2 their best development. The 
: further history will record 
the progressive extinction of 
these societies by centripetal 
invasion. 
The relations of the zones 
_ to each other are shown in the 
1.51. 
Contour, Interval 
SO Meters 
um-Ledum invading 
er 
orest 
ore: 
og 
rrMarginal Zone 
3B 
a 
Prete Gee + eee eS nt 
¥uiv 
vy 
My. 
(Aa 
bid 
a SES 
ee oy 
¥ 
v, 
Fic. 36.—Map of Raspberry Island (upper left-hand corner) and the bog area on a larger scale: the location of quadrat 9 is shown 
