第四纪古风成沙,是指现代风成沙出现以前的第四纪期间由风的地质作用所形成的沙质沉积物。国外对第四纪古风成沙或古沙丘(又称化石沙丘)已有较多研究,国内不少地方亦屡有发现,但系统研究尚少。

The Ordos Plateau is the area where the Quaternary ancient eolian sands are well developed and they have been discontinuously discovered since very early time. The authors, after their recent investigations, have discovered that the Quaternary ancient eolian sands are distributed in varying depth in the studied area.According to the state of preservation, the ancient eolian sands can be classified into two types: the buried type and the relict type. The buried eolian sand is more complete and can be distinctly seen along the north margin of the loess plateau, especially the Yulin region of northern Shaanxi. The strata with ancient eolian sands can be divided into five groups in order from top to bottom: Holocene, Late Pleistocene, the upper and lower parts of the Mid Pleistocene and the Early Pleistocene series. They can be compared with the loess profile in Luochuan. The buried ancient eolian sand occurs in the loess strata as the intercalated bed of fine sand and sandy loam, including sandy Heilu loam and sandy brown soil, it does not spread continuously in the horizontal and longitudinal direction and constitute lit par lit depositional series with loess and silty loam.