Geology Reference
In-Depth Information
(b)
Figure 3.3.
(b) These plates of granite have been produced by frost riving in the Rocky Mountains of
Colorado.
Figure 3.4.
Disruption of granite slabs by tree roots, Wudinna Hill, northwestern Eyre Peninsula, South
Australia.
as haloclasty, has been invoked in explanation of tafoni and alveoles (see Chapter 10), as well
as general disintegration, in arid and semi-arid regions both hot and cold, coastal and interior
(Joly, 1901).
Tree roots have obviously disturbed and exposed granite slabs and blocks (Fig. 3.4) and at a
smaller scale the roots or hyphae of lichens disrupt crystals and fragments (Fry, 1926; McCarroll and
Viles, 1995). Algae and bacteria also bore into crystals thus creating pathways along which water
can penetrate. Indeed, there is increasing evidence that nannobacteria or midget or dwarf bacteria
