Rit (Vísindafélag Íslendinga) - 01.07.1962, Side 41

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the clay on the east side was deposited in a lake at the edge
of the thick kuhbaberg lava.
The lignite material which I sampled here and at Hrúta-
fjarðará has been analysed by Pflug (1959). He found a
“cool” flora with conifers, comparable with that of Breiðavík
in Tjörnes. This seems to indicate Uppermost Pliocene or
Lower Pleistocene. I think it wise, however, to retain still
the possibility that while the Breiðavík flora refers to low
ground, the flora of Holtavörðuheiði may refer to a much
higher elevation, in which case its cool character is not ne-
cessarily an indication of a recent age.
6. Grímstunguheiði, Auðkúluheiði, and Stórisandur. The
outcrops which have been described above in Plúnavatnssýsla
are all in the outskirts of the region occupied by the Young
rocks. The main mass forms an unbroken flat cover, 30—40
km broad from north to south and 80—90 km long in the
E-W direction, if we here restrict ourselves to the area north
of the socles of the glaciers Hofsjökull and Langjökull. Typi-
cal for the studied localities are kubbaberg lavas and colum-
nar lavas and often mixed types, but thin layers of basaltic
breccia, largely glassy (palagonite breccia), and globular
basalt may occur.
Going south from the edge of the Young rocks at Vatns-
dalur, into the area between the Blanda river and Arnar-
vatnsheiði, we find the same character in the north hut turn
upon a mixture of lavas, breccias and tuffs in the southern
parts. The plateau character is everywhere evident, the lavas
are flatlying, and the predominantly fragmental rocks set
in at an elevation of about 600 m. At Skúti we found two
magnetic groups, and farther south, with increasing elevation
we find at least two further groups, although it is not pos-
sible to draw the boundaries with great sharpness because of
paucity of outcrops in the flat terrain. There is an extensive
reverse group, possibly indentical with the topmost one in
Stóradalsháls at Blöndudalur, and the one in the Blanda gorge,