Rit (Vísindafélag Íslendinga) - 01.07.1962, Page 82

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Hrafnabjörg.
In the steep west and north wall of this isolated mountain
the structure is well seen, Fig. 39. The wall is made of more
or less clearly stratified tuff-breccia of a visible thickness of
about 250 m. This is covered by a cap of grey basalt lavas
that are much weathered and have been striated hy a south-
flowing glacier.
The lowest horizon is seen at the north comer, at 350 m
above sea-level. Here we have light-brown slightly south-dip-
ping layers of sand and clay, 10—12 m thick (x in Fig. 39).
Scarse basalt pebbles, 5—10 cm in diameter, and without glass
coating, occur. This is probably a fluviatile sediment, a flat
wet, occasionally flooded plain. On this is a primary tuff with
bombs, a primary breccia, and a mass resembling hardened
scree. At y the breccia is a fine-porphyritic kubbaherg, a
breccia from crumbled kubbaberg and a breccia of crumbled
bombs. Towards the top of this mass can be discerned a few
thin kubbaberg lavas which have flowed down a steep north-
facing slope. The lavas are separated by thin layers of brown
very fine tuff. One such layer of tuff or clay in a very steep
slope might indicate deposition under water.
At 375 m this mass is, without a sharp boundary, covered
by a coarse breccia from the same material, but being a por-
ridge of basalt fragments in a brown glassy matrix. This mass
is very thick, reaching the local edge of the wall. It contains
here and there irregular lava masses, is quite without strati-