Rit (Vísindafélag Íslendinga) - 01.06.1939, Blaðsíða 17

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3. The Gravel Formation. As was mentioned above
the gravel formation nowhere forms a continuous plant-
formation, but it appears here and there among the peat-
formation, and therefore little dependence can on the
whole be put on the results of the investigation there. Yet
the high A % together with the high Ch % is in accordance
with investigations on gravel elsewhere in the country (cf.
Mölholm Hansen, 1930), A = 60,0, 77,9 and 79,2, but
Ch = 50,0, 43,6 and 41,1. The investigations were made
at Lækjamót, table 19 B, p. 82. These three lastnamed
plant-formations all have this in common, that there is no
moss and the formation therefore has the colour imparted
by the soil, the sand dark grey; the sandy gravel yellowish-
grey and the gravel reddish-brown. The quantity of the
vegetation is also according to the amount of nourishment,
0,8, 1,6 up to 3,5. The number of species also corresponds
in the two first, but is easily twice as great as in the last.
The characteristic plants of the sand are Atriplex hastatum
L., Honckenya peploides L., Ehrh. and Cacile maritima
Scop. var. latifolia Desf., of sandy gravel Agrostis alba
L., but Plantago maritima L. is common to both these
formations. Again characteristic of the gravel are Silene
maritima With., which also occurs in the sand, Festuca
rubra L., which is found in all the plant-formations, Ar-
meria vulgaris Willd., Thymus serpyllum L. var. pro-
strata Hornem., Arabis petræa (L.) Lam., and Silene acau-
lis L., and the four last-named are common to the gravel
and sandy gravel. The distribution of Agrostis canina L.,
Equisetum arvense L. and Luzula spicata, (L.) D.C. also
shows clearly the relationship of the gravels, which must
here be counted with the peat formation (cf. below Peat-
Formation).
B. THE PEAT FORMATION.
Observations 1—5 were made in the lava on June 25—
26th and July lst 1933, h. above sea level up to 50 m.