Rit (Vísindafélag Íslendinga) - 01.07.1962, Page 129

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the level down to the present one, for observations of con-
siderable flow of water from Kleifarvatn to Lamhhagatjöm
mean very probably that the subterranean drainage and the
level of the lake are controlled by tectonic fractures. Without
these fractures the level would be higher and very likely
reach the pass height of the basin. This height is now 168 m
in the northeast and could have fitted very well with the
Stapi level. In the southwest the height is now around 160 m
but here the great thermal activity and young volcanic ac-
tivity suggest tectonic disturbance. Before the subsidence of
the median part of the lake bottom this southern area could
have been higher then 180 m, that is, the level would have
been determined by the height of the NE col. Because of
later glaciation(s) it may be difficult to prove this theory by
more direct arguments than here given.
Younger than the western wall of Lambhagi is a thick
cover of hard, rather well stratified breccia-conglomerate of
brown to greyish colour on the northern and southern part of
Lambhagi; the layers are rich in subangular basalt blocks of
5—20 cm in diameter. They rest on a 1 m thick weathering
layer derived from the breccia. In the north the layers cover
partly the western wall with a dip of up to 48 °W, and even
on the nearly horizontal surface of the head they dip 35°
north. There are no clear signs of eolian nor fluviatile tran-
sport. Possibly this could in part be shore sediments advanc-
ing into the high-level lake from the Vatnshlíð, but in part
at least the layers are a ground moraine or reworked by a gla-
cier (cf. weathering mantle and moraine of Ármannsfell).
It is quite possible that Lambhagi is a levelled heap of glo-
bular breccia formed by eruption in the lake at the Stapi level.
Coming back to Innri Stapi it would seem that it is an ero-
sional remnant of a more general bench and that the pro-
montory as such was formed by lake erosion at or near the
present level. In about the present state of the promontory
it was overrun and striated by a glacier flowing SW along