Rit (Vísindafélag Íslendinga) - 01.07.1962, Page 111

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erosion. Further we see that the mountain cluster northwest of
Ingólfsfjall is tectonically disturbed. This disturbance is quite
old for the erosional forms are on the whole smooth, especially
in contrast to the young disturbed forms west ot Reykjafiall.
For further discussion of this I may refer to my paper quoted
above and to the section on Grafningur—Lyngdalsheiði he-
low.
An important section with lignite which we shall now con-
sider is found near the farm Stóri-Háls just north of Ingólfs-
fjall.
Stóri Háls. A section of the slope above Stóri Háls, along
the gully Bæjargil, is shown in Fig. 57. The upper group of
tuff-breccias here rests at 185 m on a 25 m thick moraine,
which should correspond to m2 in Ingólfsfjall. Below this is
hard brown clay and then alternating layers of sand, gravel
and clay in which is a layer of lignite a few cm thick.
A little below this place the N-S fracture zone runs along
the slope, causing much crushing of the strata and leading to
some difficulty in getting a clear section. There is a slight
downthrow, which can he traced with the aid of the lignite,
Fig. 57. Below the fault zone we have a primary coarse basalt
breccia of normal polarization resting on the lignite. This
breccia would correspond to nx. Lower we have sand and
gravel. There is also glacial clay which possibly is a young
deposit but it may belong to the sand and gravel series, in
which case its equivalence with mt would be especially con-
vincing.1)
The structure of the upper group of tuff-breccias is clear
a little north of Bæjargil, Fig. 58. On the plane surface of the
moraine (1) we have the front and sloping surface of a pri-
J) A study of three samples of lignite is being done in the Geological
Institute in Cologne, and will appear shortly. Referring to Fig. 57, no. 1
was taken below the breccia 4, no. 2 below the number 5, and no. 3 at
the outcrop farthest to the right.