Great Artesian Basin
Most water enters the rock formations from the higher ground near the eastern edge of the basin (in Queensland and New South Wales). It very gradually flows towards the south and west. A much smaller amount enters along the western margin in arid central Australia, flowing to the south and east. Because the sandstones are permeable, water gradually makes its way through the pores between the sand grains, flowing at a rate of one to five metres per year.