STUDIES ON THE VEGETATION OF ICELAND 115 
northern slopes of the hills (cf. fig. 23), abutting above on the melar, 
whence the soil rolls down on to it, and passing below into the knolly 
mo. More rarely the snow patches occur in the shape of large depres- 
sions having the form of a parabola in the western and southern 
slopes of the hills. The shape of these large patches of snow is 
very characteristic; above they are separated from the melar by a 
narrow steep edge. The sides of the snow patch slope strongly 
above, are less steep further down, and finally pass into the bottom 
of the patch which as a slightly hollow surface slopes gently towards 
the mouth of the snow patch. The shape most of all resembles a 
large shovel dug into the slope. The bed ofa rivulet extends some 
way into the patch. Outwardly this form, too, passes into the 
knolly mo. 
The surface is level and without knollsin both forms 
of snow patch, as may be seen with sufficient plainness in the 
figures. 
While the vegetation is uniform throughout the whole snow 
patch in the first type, differing only according to the exposure, a 
distinction can be drawn in large snow patches between a marginal 
zone, the vegetation on the sides, and a bottom vegetation. The 
vegetation is most characteristic in the large snow patches, a number 
of snow patch plants being exclusively found here, just as the mar- 
ginal zone is a formation peculiar to the large snow patches. As 
regards the vegetation of the bottom, it seems to correspond to that 
af smaller snow patches with a northern exposure, while the vege- 
tation of the sides corresponds to that of smaller snow patches 
with a southern exposure. Hence the floristic relations of the snow 
patches may be dealt with under one head, the following three 
formations requiring to be treated: 1) a marginal zone with Betula 
nana, and possibly Juniperus communis, 2) a Geranium belt compris- 
ing small patches having a southern or western exposure and the 
vegetation of the sides of the large snow patches, and 3) the bot- 
tom vegetation, which comprises, in addition, the vegetation of snow 
patches having a northern exposure. Table 25 A, 1—6 shows the 
circling results for the vegetation of the snow patches. No. 1 is the 
vegetation of the marginal zone, Nos. 2—4 the Geranium belt, and 
Nos. 5—6 the bottom vegetation. Nos. 1, 2—3, and 6 originate from 
the same large snow patch, 5 and 4 represent the smaller patches, 
respectively with a northern and a southern exposure. 
8* 
