Geology Reference
In-Depth Information
(a)
(b)
Figure 11.15.
(a) Slipped triangular slab, Little Wudinna Hill, northwestern Eyre Peninsula, South Australia,
and (b) tension fractures at edge of space vacated by displaced slab.
Little Wudinna Hill has slipped, and though the granite is of the same order of roughness, the
blocks standing on them are stable. The reason is that, though in general view smooth, the granite
slopes and the surface of the granite slabs and blocks themselves are, in detail, very rough or pit-
ted. A micro-relief of a few millimetres has developed and, even when lubricated by water, friction
inhibits slippage on these slopes. Yet some slabs have clearly migrated under gravity on slopes that
are more gentle than those on which blocks stand firm.
11.3.4
Chaos
Displaced slabs in chaotic arrangement have been noted at several sites associated with A-tents, as
for instance on the western side of Wudinna Hill (Z in
Fig. 11.9)
,
on Quarry Hill, near Wudinna,
