It has been long held that the buried soil under sand dunes on the major sand lands in northern China formed due to the climatic changes of the Holocene, which could be used as a proxy record to reconstruct the past climate in warm-humid periods.

The soil physical composition,organic matter,total nitrogen,total phosphorus, total potassium and pH of Salix psammophila ccheckerboard and contrast sand of Dalate county were investigated in 2005,the effects of Salix psammophila checkerboard on physical and chemical characteristics of sandy soil were analyzed.

The sand ridges on Stratum U14 which is bellow seafloor 90 m are buried sand ridges,and belong to TST(transgressive systems tract) of 320~200 ka BP,and the upper bounding surfaces of the sand ridge units are therefore considered as the MFS(maximum flooding surface) of this transgressive.