Rock geology and surface soils

1145. Surface soils generally take their names from the rocks on which they rest, and the debris from which forms their principal component part; soils of this nature being generally easily recognised by their colour. 'Thus,' as Morton observes, 'we find argillaceous soil resting on the various clay formations-calcareous soil over the chalk, and oolitic rocks ; and siliceous soils over the various sandstones. On the chalk, the soil is white; on the red sandstone, it is red ; and on the sands and clays, the surface has nearly the same shade of colour as the sub-soil.'