2.1.1 Dissected Western Uplands associated with Palaeozoic sedimentary and metamorphic rocks

In general, the landscapes of the Palaeozoic sedimentary rocks are characterised by undulating low hills dissected by a dendritic drainage pattern that forms the upper catchments of the Moorabool River, Leigh River and Woady Yaloak River drainage systems. The primary drainage trends are parallel to the strike of the bedrock strata and the secondary drainage is controlled by geological boundaries (i.e. lithological boundaries) and rock structures (i.e. faults, joints). The sedimentary rocks generally form the drainage divide along the northern eastern boundary of the CCMA region and rise to a high point of 740 m north of Barkstead.

The larger landscape elements are remnants of the deeply weathered Palaeogene palaeosurface. At Ballarat, the weathering extends up to 100 m below the surface, with secondary mineral development (e.g. kaolin clay) producing the typical bleached and pallid regolith profiles in the Palaeozoic rocks. The oxidation of iron-rich groundwaters has precipitated iron cement into joints and the upper regolith materials. In some areas, remnants of Palaeogene weathering in the form of siliceous and ferruginous duricrusts are preserved by the inversion of relief.

The Palaeozoic sedimentary rocks generally have texture contrast soils, often with well developed, bleached subsurface (A2) horizons. However, the geologically recent landscape development and the significant land use change of the past 150 years have stripped the profile in many places. Intensive shallow gold mining has disturbed many hundreds of hectares such that the original soil profile no longer exists and new soil profiles have started to form.