 Reefs can increase in diameter by per year, and grow vertically anywhere from per year; however, they grow only above a depth of due to their need for sunlight, and cannot grow above sea level.When Queensland edged into tropical waters 24 million years ago, some coral grew, but a sedimentation regime quickly developed with erosion of the Great Dividing Range; creating river deltas, oozes and turbidites, unsuitable conditions for coral growth.10 million years ago, the sea level significantly lowered, which further enabled sedimentation.