Next was a visit to
Mount Hay, to fossick for thundereggs. We
were again the only tourists there. It still
is dead season and Australians avoid that
area due to the high temperatures.
These thundereggs are 120 million years old and
formed in a complex way. In the fluid lava
from an ancient volcano, gas bubbles formed
cavities. Later the area was flooded and
during million years the cavities were
filled with mineral rich water. Molecule by
molecule mineral crystals grown inside the
bubbles and the lava reverted to rhyolite.
This rhyolite was weathered to a clay-like
substance and the bubbles with mineral
crystals could be found in the ground.
