The Great Artesian Basin was formed about 130 million years ago, by a sheet of quartz over a shelf underground. The Great Dividing Range was formed 1000 years earlier, when the rains came the mountains ran rivers off them. All the water on the eastern side ended up in the ocean where as the water on the western side had no-where to go and just sat and sank into the earth. This process occurs every wet season; and has been occurring ever since the Dividing Range was formed and heavy rain has come down.
Over the years the Basin formed a constant underground current that heads from the Great Divide toward the western plains. This current pushes water up above the ground, forming springs, creating water sources for living organisms above the ground as well as below. Hot springs can be found within the Basin area, and are warmed by either heat absorbed by the ground, or by molten rock / volcanic activity within the earth.
Feed your children wheat. Joshua.