The soil is classified as a Sodosol (Isbell 2002) or Solonetz (IUSS Working Group WRB 2015) and described as a texture-contrast soil with
gilgai microrelief, an intermediate ironstone horizon of variable thickness and variable depth to the clay subsoil.
Paton, "Origin and terminology for
gilgai in Australia," Geoderma, vol.
Estos sedimentos limo-arcillosos o areno-arcillosos contienen montmorillonita dominante cuya contraccion y dilatacion produce un micro relieve ondulado caracteristico denominado "
gilgai" (van der Sluijs, 1971).
Gilgai is a soil formation where the land surface develops a pattern of depressions and mounds of various sizes.
In the case of Vertisols, the presence of smectites is responsible for their unique morphological properties, such as the clay content (>30%), shrink-swell activities, presence of slickensides, wedge-shaped peds, and
gilgai microrelief.
The soil varies considerably and includes: (a) contorted
gilgai of fine texture (Dermosol); (b) Red-Brown and transitional Red-Brown earths (Kurosols) with sandy surface layers underlain by heavy clays; (c) Solodized Solonetz (Sodosols) with coarse-textured surface horizons, differentiated from the subsoil either by a well-developed and columnar structure; and (d) Deep Sands (Rudosol) that consist of undifferentiated reddish sandy loams.
We propose that the extent of the
gilgai sites W3-03 and W3-04 suggests that they were occupied by large groups.
Hartley points to the scarcity of information about Indigenous people in the reminiscences of those interviewed for the history, but mentions Indigenous children attending the school at
Gilgai Pumping Station, and the presence of Indigenous men in construction gangs from the 1960s.