Geology Reference
In-Depth Information
(c)
Figure 7.5.
(c) In the central Sahara (Rognon, 1967).
Figure 7.6.
Castle Rock, in the Mt Manypeaks area, south coast of Western Australia; note flared sidewalls (X).
Mt Manypeaks district, east of Albany (Twidale, 1981 see Fig. 7.6). But well-foliated gneiss is not,
in itself, a guarantee of castellated form and, on the other hand, many bornhardts are developed on
gneissic rocks and many castellated hills are formed in granite. Though structure is a significant
factor in the genesis of castle koppies, it is not an overriding one: evidently the structural base has
been exploited in particular ways and conditions, in order for the angular form to evolve.
Some workers associate koppies with particular climates and processes. Godard (1997) consid-
ers that castellated inselbergs are either due to frost shattering, or are large residual masses remaining
after differential subsurface weathering, or are the cores of inselbergs remaining after either scarp
