10. NAMBUNG
This area is mainly within the confines of the Nambung National Park. Caves and
other speleological features have the prefix SH for South Hill River, an area
which includes some features north and south of the Park.
10.1. History:
The sand dunes of this area which are 120 m above sea level, were recorded by
17th century Dutch Navigators. In 1839, caves were first noted in the area by a
member of Sir George Grey's ship wrecked party on their 500+ km walk back to
Perth. In the 1900's, guano was mined from some caves, at first spasmodically
by local farmers and then by an ill-fated scheme by the then Minister for
Agriculture. A temporary reserve was placed over the valley of the Nambung
River in 1927 to protect the caves. At the time of the phosphate mining, The
Pinnacles, only a few miles south, were not mentioned, possibly because they
were covered with sand. However, it was these karst features which prompted the
formation of the present Nambung National Park in 1966. The first speleological
activity occurred in 1962 and since then the area has seen intermittent bursts
of activity. A comprehensive caves list and accounts of the area was published
in 1973 (Shoosmith, Poulter). The National Parks have gated delicate caves in
consultation with speleos.
10.2. Geomorphology:
The Nambung River sinks in a series of lakes and inflow points caused by
repeated deflections of the river by active dunes. The complicated hydrology of
the Nambung has been described by Shoosmith (1974) which tells of 1 km long
lakes appearing virtually overnight and of solution pipes spouting columns of
water.
Though there are a few caves which are solution tunnels which flood to the
roof, for example, Brown Bone Cave, most are inclined fissure collapse caves,
often well decorated. In Quandong Cave there is a preponderance of volcano-like
stalagmites formed over small soil cones below solution pipes which are not
calcite filled.
The spectacular Pinnacles are the result of subsoil karst erosion (Lowry 1973),
the soil having been deflated after the stabilizing vegetation had been killed
by the encroachment of active dunes.
10.3. Caves:
The inclined fissure caves of the Park, for example, Cadda Cave SH 18,
Weston Cave SH 2, Thousand Man Cave SH 7 and Pretty Cave
SH 9 to name a few, offer good potential for photography, mapping and
exploration.