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Perth Soils
They don't call us sandgropers for nothing. Western Australia and certainly Perth is very sandy. But there are sands and sands. If you are used to decent soils, you probably can't see much point in subdividing sands. Yet it does matter. Suppose you compare a soil with 2% water holding capacity with one with 6 %. They are both at the bottom of the scale but one has 3 times the capacity of the other.
Simplified map of the soils of the Perth region.
1
Soils of the youngest dunes. Usually very coarse sand with low water holding capacity. Pale yellow sub-soils, lime at some depth, tuart trees when far enough from the coastal winds
Soils of somewhat older dunes. Deep yellow sub-soil with fair water holding capacity often with lime. Tuart trees
2
Alluvial soils. A mixture, some with heavy texture and high water holding capacity.
4a
3
Soils of the oldest dunes. Coarse sands, strongly leached with pale yellow sub-soils
Sandy surface soils overlying alluvial soils
4b
Diagram to represent a section across the coastal plain showing the downward movement of excess rainwater through the sands and then slow lateral movement as groundwater.
Soils of the Darling range and scarp, many with much pea-sized gravel
5
Many native plants have deep roots which can tap this ground-water, When it appears above the surface it forms lakes and wet lands