摘要
A Pliocene ancient dune was discovered in Baicha River basalt on the southern bank of the Xilamulun River in the northern Chifeng. This discovery proves that Baicha River valley area in the northern Chifeng also had the arid circumstance with strong wind which was required for the formation of an ancient dune,quite similar to the extensive growth of grass dunes in the nearby area. This paper also demonstrates the finding of calcareous concretions with excellent sphericity in the ancient dune,whose diagenesis and ancient climate change significance deserve further investigation.