The Botany of Iceland - 01.12.1930, Blaðsíða 125

STUDIES ON 'I'HE VEGETATION OI' ICELAND
115
northem slopes of the hills (cf. fig. 23), abulting above on the nielar,
whence the soil rolls down on lo it, and passing below into the knolly
mo. More rarely Ihe snow patches occur in the shape of large depres-
sions having the form of a parabola in the western and southern
slopes of the liills. The shape of these large patches of snow is
very characteristic; above thev are separated from tlie 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
oí 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 of a rivulet extends some
way into the patch. Outwardly tliis form, too, passes into the
knolly mo.
The surface is level andwithout knollsinbothforms
of snow patch, as may be seen with sufficient plainness in the
íigures.
While the vegetation is uniform throughout the whole snow
patch in the first type, differing only according to tlie exposure, a
distinction can be drawn in large snow patches between a marginal
zone, the vegetation on the sides, and a bottoin vegetation. The
vegetation is most characteristic in the large snow patches, a number
of snow patch plants being exclusively found liere, just as the mar-
ginal zone is a formation peculiar to the large snow patches. As
i'egards 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 mav be dealt with under one head, the following three
íormations requiring to be treated: 1) a marginal zone with Betula
nana, and possibly Juniperus communis, 2) a Geranium belt compris-
lng small patches baving 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 tbe bottom vegetation. Nos. 1, 2—3, and 6 originate from
the same large snow patch, 5 and 4 represent the smaller patches,
vespectively with a northern and a southern exposure.
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