The quartzose silcrete of the Strzelecki Track formed in the Tertiary Era, as a duricrust formed through silica rich mineral deposition from groundwater at the low lying fringes of the Flinders Ranges. It appears to be cryptocrystalline in nature, made of a minute crystal structure also typical of chert and chalcedony.
Highly resistant to weathering, the silcrete formation reveals some very finely detailed fossil casts of vegetation. The fossils in this formation contain casts of plant detritus of varying species, one of which appears to be Casuarina.
This formation has intriguing layering of well preserved crushed quartz, silcrete and sand calcite balls as seen in this vertically upturned rock.
The outermost layer of the formation of sand calcite balls is likely to have formed in sand by evaporation of alkaline groundwater.