2.1.3 Dissected Western Uplands associated with Cainozoic gravel and sediments

The Palaeozoic rocks of the Western Uplands are capped in places by sands and gravels, which are remnants of Palaeogene and Neogene sediment deposition.

The Palaeogene White Hills Gravels and equivalents are the erosional remnants of an extensive sheet of fluvial sediments that once covered much of the Western Uplands. The coarse grained sediments form a quartz-pebble conglomerate, often ferruginised and sometimes silicified. The thickness varies from around 30 m (such as at Sago Hill quarry) to a few metres. Landforms include isolated flat-topped mesas overlying Palaeozoic rocks (Napoleons), break-of slope deposits between the overlying basalt and the underlying Palaeozoic rock (Lal Lal Reservoir) and broad tablelands fringing the overlying basalt (Haddon-Nintingbool).

Neogene sands generally fringe the south of the Western Uplands as a dissected tableland. A remnant of the Late Palaeogene marine transgression, the sands are often ferruginised by groundwater processes. Erosion and salinisation are commonly associated with this landform. Soil types include sands and texture contrast soils, often with ferruginised nodules (‘buckshot’).