ge seat 
ae ae 
~~ Scheuchzeria- 
hagnum 
Boundary horizon 
calluna-eriophorum 
peat 
N 
K 
N 
N 
N 
ALSGOTROPHIC 
PED T FORMATION 
( 
») I 
1 
YY) IIDAK 
4 
Older sphagnum 
peat 
(COCO 
Scheuchzeri 
carex-sphagnum, 
eriophorum peat 
Pinus and betula 
forest peat 
le yyy) 
))) 
| Alnus peat 
Phragmites peat 
* Rasmus peat 
55 
Pesos atote estates 
iso Pesteenroeere KS ‘ 
sesete re seese} Colloidal peat 
eas BRS eotetatecetee 25 
necatatetatetetonecete fot 
statetetasetatats 
2,0 ,9 0 .%.@ 
seis nenennes 
==—~===-| Clayey phase 
‘| Diluvial bottom 
Fic. 4.—Generalized section through North 
German peat deposit 7 m. (22 feet) in thickness, 
showing succession of layers of peat sinthelal: 
after WEBER (36). 
BOTANICAL GAZETTE 
[AUGUST 
water by vegetation units 
there is not only a grad- 
ual decrease in available 
ground water, but in min- 
eral food constituents as 
well. The earlier plant 
communities and _ those 
which occupy a position 
near the margin of the 
asin derive their salts 
from the water or from the 
soil on which they grow. 
For the succeeding units 
this becomes less and less 
in amount. When com- 
pletely filled, the inward 
sequence of peat material 
(the horizontal section) 
and the upward sequence 
or vertical section of plant 
remains may show char- 
acteristics successively dis- 
tinct in content of mineral 
matter, such as lime, and 
of water incident to the 
increase of thickness of 
peat. The difference be- 
tween the total mineral 
content of a peat deposit 
and an adjoining lake has 
been shown for Cranberry 
Island at Buckeye Lake, 
Ohio (3). The term eu- 
trophic is used by WEBER 
(36) for types of peat formed 
in water rich in mineral 
nutrients, and oligotrophic 
