Rit (Vísindafélag Íslendinga) - 01.06.1975, Side 71

Surface. As described above the surface of the mýri is usually
öiound pattemed. The mounds, however, vary according to topo-
graphy, vegetation, moisture content of the soil and location. Most
cornmonly the mýri occurs mth rather dense and somewhat fine,
rounded or semi-conical mounds, which are most frequently formed
by moss. This is particularly applicable in lowland mýri areas with
slight slope and medium moisture content. The vegetation differ-
ence between mounds and hollows is often slight to non-existent,
but in other parts it is significant as will be related later on in
connection with individual sociations. This depends on the coarse-
ness of the mounds and the moisture content of the mýri. Where
Jt is wettest there will always be some vegetation difference, moss
then almost exclusively covers the mounds as do the shrubs and
the dry ground species of the mýri. Often the mýri is pattemed
■with low, flat mounds, i.e. the border between hollows and mounds
becomes vague, in such instances the mound is rounded and quite
large. This applies e.g. most often to the Scirpus mýri. Such mounds
do not consist of moss except to a very slight degree. They have
developed rather through some kind of transferral of matter in the
soil or because of particular growth of phanerogamous species. On
mountain slopes the mýri tracts are often mainly level without
any discernible reason. The snow cover may in some parts be a
contributing factor, however, because there often is a thick snow
cover in mýri tracts situated on mountain slopes and moors. Furth-
ennore, it would seem that mýri stretches in districts where the
snow cover is heavy are more level than elsewhere. This, however,
Way not be asserted, but it is quite sure that under hill protmsions,
"where drifts form there are always level belts of mýri. I have only
observed on one location a tme ridge mýri. (Steindórsson 1945,
P- 399).
Formation. The mýri in Iceland is with few exceptions or exclu-
sively soligene, i.e. it owes its existence to ground water, which
remains constant because of adflux and little evaporation. The
precipitation at the site is also a contributing factor, so that the
*nýri in some parts approximates an ombrosoligene type, but this
bind of mýri belongs to oceanic areas. Fægri defines ombrosoligene
tnýri as follows:
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