Pedogenesis of red soils overlaid coral reef terraces in the Southern Taiwan

Red soils developed above the reef limestones are commonly observed in the world. Their characteristic properties of high contents in clays and iron-oxides, reddish hue are usually classified themselves as Inceptisols, Alfisols, Ultisols or Mollisols in Soil Taxonomy. The genetic contexts between the soils and beneath limestone have been revealed for gauging paleo-landform surface processes relating to paleoclimatic shifts since the late Pleistocene. There are levels of reef marine terraces in altitude in the Hengchun Peninsula of Taiwan. Their surfaces are covered by thick reddish soil enriched with iron-oxides. However, these terra rossa-like soils distributed on the reef limestone are actually developed from heterogeneous detrital materials, instead of developing from the insoluble residue of the limestone. According to the Soil Taxonomy, the soils on the higher terraces are classified as the Typic Paleudults or typic Kandiultults. They are equivalent to the Alisols in WRB system. The soils on the lower terraces are classified as Typic Udipsamments and Lithic Eutrudepts, and they are equivalent to the Arenosols and Cambisols respectively. This study suggests that the terra rossa-like soils in the study are developed from the parent materials of fluvial deposits which are subject to the landform surface processes during the Interglacial.