Rit (Vísindafélag Íslendinga) - 01.07.1962, Page 102

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coating still turns outwards and allows us to trace the sur-
face of the disintegrating bomb. Many stages in this process
can be found just as was the case in Hrafnabjörg. In Hrafna-
björg the creep of the mass was easily referable to the steep-
ness of the original stratified tuff-breccia. The conditions are
not so clear in Vörðufell, but my impression was that, as in
Mosfell, we have rather a mass that has flowed nearly hori-
zontally or in a gentle slope.
While this character is predominant on the summit just
south of Valagil we find a series of dipping layers near the
trigonometric point 379, very similar to the conditions south
of Mosfell. On the 20°S dipping slope of thin lava tongues
Fig. 53. Section on top of Vörðufell.
1 — thin lava tongues; 2 — primary breccia; 3 = very thin lava
tongues or lamellae; 4 — coarse breccia, largely scree.
(kleprar), Fig. 53, rests a primary breccia of bomb fragments
such as we have just described. With a dip of 30°, further
very thin lava tongues, or rather lava blades (thickness down
to 1—2 cm) have flowed down the front of the breccia. Final-
ly, these layers have been covered with a thick coat of breccia,
similar to the first one, but with progressively less dip and
with less glass coating left on the bomb fragments. The
breccia is partly very coarse, with lava blocks up to 30—40
cm. This basalt debris comes partly from a disintegration or
weathering of larger basalt masses, possibly lava flows.
The mentioned lava tongues are rather porous, which sug-
gests a short distance from the source, but the bomb frag-
ments in the primary breccia are mostly quite dense. It is
at present not quite clear how this should be interpreted.
Dense lavas usually develop from an original frothy mass