MICROPALÆONTOLOGY OF POSTGLACIAL DEPOSITS. 491 
a lime-pollen grain was found, and there seem to be several reasons why this 
layer should be referred to the A-zone (behaviour of alder- and pine-pollen 
etc.). The importance of the Salix vegetation in older times is shown by the 
percentage figures from samples 5-9, which are respectively 478, 35, 154, 162, 
and 273 per cent. These figures, however, must not be interpreted as 
Trxt-Fic. 18. 
0 10 20 30 40 50 60 70 80 
1 
2 
1-4 
3 
4 
2— 
-a —o = 
o 
34 
N 
| u- 7 
= ~~ 
| 
n 8 
| l 
I 
y 
LJ gl 
—o— Alnus. —o— Betula. —e— Pinus. nn Ulmus. 
— Quercus. ------- Tilia. --g- - Corylus. 
showing that the Salices had their maximum occurrence during that stage 
of the formation of peat represented by sample 5 (478 per cent. “ Sala”): 
This dominance is only relative. It might be caused by the gradual decrease 
and disappearance of the Shetland forest trees. 
