SOIL LAYERS ON HILLSLOPES: A STUDY AT NOWRA, N.S.W., AUSTRALIA

Abstract

Summary Three separate soil systems occur on hillslopes near the N.S.W. south coast. The proof of separateness lies in pedologic, stratigraphic, and geomorphological criteria by which the soil layers are shown to be independent entities. The sequence of soil layers is considered to be evidence of a K‐cycle soil history (after Butler, 1959) involving alternating stable and unstable conditions. Evidence suggests that K‐cycle instability (Ku) has resulted from a change to relatively dry climatic conditions and has involved processes such as hillwash, gully erosion, and soil creep; K‐cycle stability (Ks) is characterized by soil development during relatively humid phases. On the south coast the Minnamurra layer (minimal prairie soil) represents the youngest or K l cycle; the Nowra layer (grey‐brown soils) represents the next oldest or K 2 cycle; the Wandandian layers (red podzolic and yellow podzolic soils) represent the oldest or K 3 cycle.