Sandstone is fine grained and relatively strong as a building
material. It also has an unusual banding that often forms concentric
rings and unusual colourings. Remember that sandstone was originally
deposited in the Mesozoic Era at a time when dinosaurs walked the
earth (about 200 million years ago).
you drive up the range from Helidon to Toowoomba, you know you are
driving up to a high plateau. This plateau is made up of basalt.
Around 22 million years ago, this part of the world was the site of
great volcanic activity. In the Toowoomba area, a major north-south
fissure opened, and great amounts of basalt were extruded to the
sediments along this fissure were destroyed by the volcanic activity.
However, sediments near the main fissures, say within 10 to 15 km,
were subject to a lot of heating by volcanic fluids and gases. Put
simply, Helidon Sandstone was flushed with hot waters and gases and
this altered the make-up of our sandstone.