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. In this paper, an alternative is put forward to explain the new observation obtained from the sand lands of
Northeast China, and the past human activities are suggested as the dominating factor for the formation of the buried soil layers in the sand dunes. This explaination is supported by the facts that the formation ages of the buried soil layers in the same sand land are not simultaneous, the mature degree and thickness for the buries soil layers in the same sand dune decrease from bottom up to top, and the burrying process of the modern soil on sand dunes and on inter-dune lowlands is being under way owing to the human induced desertincation in present. These facts are very difficult to be explained by change in wettness or in precipitation. It is more possible that the settlement of population in the sand lands in the past led to the mobilization of the sand dunes, and the human-induced descrtification caused the soil to be buried by the drifting sand, forming the buried soil layers under sand layers. In spite of this, a stable climate with wetter condition may be helpful for the recovery of the vegetation and soil after the sand layers above the buried soil is deposited, and may thus be Anportant for the formation of the alternative soil and sand layers in the late Holocene period. In most cases, therefore, the "dead soil" could not be callcd paleosoil, and it could hardly be used to indicate the past climate changes either.