Náttúrufræðingurinn - 1957, Blaðsíða 37

MYNDIR ÚR [ARÐFRÆÐl ÍSLANDS
29
SUMMARY
Geology of Iceland VI. On three Tertiary plants not described before from Iceland.
by Jóhannes Áskelsson
The fossil leaves depicted here above all occur as impressions marked in
consolidated sideromelan ash. No cuticle could be obtained. The plantbearing
stratum creeps out of the north-east slope of Mt. Þórishlidarfjall, N.W. Iceland,
in 360 m lieight above sea level. The sequence of strata is the following frorn
beneath:
a. Tertiary basalt sheets with non-fossiliferous intercalations.
b. Stratified sandstone of about 20 m thickness in the middle of which the
fossiliferous layer appears in 12 - 20 cm thickness.
c. Tertiary basalt sheets with non-fossiliferous intercalations reaching 500
m. height.
Fagus cf. ferruginea Ait. I'he leaf shown in picture No 2 occurs fairly com-
monly in the plant bed of Mt. Þórishlidarfjall. The impressions of the leaves
are on the whole distinctly marked and easy to handle. Tlie leaves found are
all more or less the same size. In shape the leaf is almost ovate-oblong, its length
being 14 cm and maximum width 6,8 cm. The petiol seems to be short, the
midrib stout, the whole leaf being slightly asymmetrical. Each half of the leaf
contains about 18 secondaries, the bottom pairs leaving the midrib almost oppo-
site each other at angles of 18°—20°, whereas the upper secondaries are alterna-
ting and leave the midrib at angles of 40°. The tertiaries are very delicate and
almost imperceptible, margin serrate, apex acuminate, base broadly cuneate.
Texture firm.
I have referred this leaf to genus Fagus, and it seems to me that it closely
resembles leaves of Fagus ferruginea Ait. Therefore it should be compared with
that species.
Ostrya selárdaliana n. sp. This species shown in picture No. 4. The leai is
almost elliptical in shape, apex acuminate, tapering base, petioled, length 12
cm, whereof the petiol reaches a length of 0,7 cm, maximal width 5,2 cm, margin
cloubly serrate or serrulate. There are about 20 pairs of subopposite secondaries
which leave the midrib at angles varying from 40° to 50°. The secondaries ex-
tending straight to the margin. Tertiaries abaxial from secondaries. Texture
firm.
The general characters which this leaf shows are very suggestive of the genus
Ostrya. The leaf is therefore referred to that genus. I have not found any Tertiary
ostrya, which completely resembles this Icelandic fossil. The genus Ostrya has
not been metioned before from the Icelandic Tertiary.
Carya sp. A terminal leaflet at Carya was found. It is shown in picture No.
5. Apex is lacking, base narrowly cuneate, margin serrate, the tooth nervation
characters are similar to those of Carya. Pollen-grains of Carya-type have been
mentioned before from the Tertiary plantbeds near Brjánslaekur (2)