A difficult place to grow
Over time a combination of rainfall and chemical weathering has formed a soil on the sand dunes that looks like the one shown here.
In the top layer of the soil, acids from decaying vegetation and rainfall have removed the iron, aluminium and calcium from the soil particles and combined with the finer particles of clay, have washed them down to form the orange/red layer.
This often becomes very hard and forms in places what is known as “coffee rock”.
The top layer is left with very little plant nutrients in a very sandy soil. Over time specially adapted plants grow and die and decay in the sand. This produces the grey layer of humus that you can see in the top of the soil.
The Cliff top dunes here at Wybung Head have had at least 150,000 years to accumulate a humus layer and are able to support a significant but different vegetation community. The soil is called a Podzol