Geology Reference
In-Depth Information
Figure 11.10.
Vertical wedge, or elongate A-tent, located low on western slope of Wudinna Hill, Eyre
Peninsula, South Australia.
found both there and on the crests of hills. Arched slabs are fairly commonplace in tropical
regions. At Cash Hill, northwestern Eyre Peninsula, South Australia, an A-tent was, in the early
seventies, partly covered by regolith capping the upland. It is possible that the A-tent had recently
been exposed by the erosion of the regolith, and that it had developed beneath the land surface.The
feature now stands adjacent to the regolithic cover (
Fig. 11.12)
.
Measurements of A-tents from several sites on northern Eyre Peninsula suggest that, if, as
seems certain, the presently raised slabs that constitute the A-tents were originally part of the
smooth hillside; their present combined lengths would in most instances exceed the space they
originally filled by some 3-4%. One on Lightburn Rocks in the Eastern Great Victoria Desert of
South Australia suggests an expansion of 5%. On the other hand, some measured at The Granites,
near Mt Magnet, in Western Australia, imply an expansion of only 1%.
Most A-tents predate human occupation or at least the recording of events, but some have
formed recently. One formed on the lower western midslope of Wudinna Hill between February
and May 1985 (Y in
Fig. 11.9
and
Fig.11.13a)
,
and two have developed at the nearby Quarry Hill,
one, a complex series of buckles, following a detonation early in 1993, the other on a stripped
surface early in 1995 (Figs 11.13b and c).
