The Oodnadatta Track provides some wonderful examples of the "gibber plains" or
Gibber plains, or as the locals say, the "hard country" are stretches of
country covered in small polished rocks or pebbles called gibbers. These are
polished fragments of the original duricrust (a layer of silica formed by the
deposition of silica, iron oxides or calcium carbonate) that capped the plain
some 65 million years ago. Fine abrasive material has swept past, wearing them
down and rounding them off during rain and wind scour.
Today, they remain as a surface lag, protecting the underlying soils from water
and wind erosion. You need to get out and pick up a few to appreciate their
smoothness and the intensity of their wonderful colours. Gibber plains are
common along the Track. A couple of favourite spots are on Allandale Station and
just north of Algebuckina where the gibbers are black rather than red-brown, the
colour being derived from the type of iron mineral (goethite) they contain.1
More information about
the Oodnadatta Track
and the many locations along the route.