Geology Reference
In-Depth Information
Figure 11.18.
Perched slabs and blocks on upper slopes of Pildappa Rock, northwestern Eyre Peninsula.
(a)
Figure 11.19.
(a) Chaos of thin slabs on slope of Quarry Hill, near Wudinna, northwestern Eyre Peninsula,
South Australia.
have either been dragged or have fallen a few centimetres or metres downslope. Vertical wedges are
due to compression and the rupture and vertical displacement of slivers of rock, triangular in cross
section, marginal to fractures, typically fractures of the orthogonal system. Several recently formed
examples have been plotted on the flanks of Wudinna Hill, Eyre Peninsula (W in
Fig. 11.9a).
11.3.6
Origin of the forms
Some displaced slabs and A-tents have been attributed to insolational heating and to offloading
consequent on erosion. They could also be explained in terms of rupture following downslope
slippage and impact against an immovable block or surface, or disruption by tree roots.
