Along the Highway No. 70, from T©n H­¬ng to B¶o ¸i , the relief has the form of intercalation between mounts, hills and lowlands developed in the NW - SE direction. The lowland topography includes different terraces: the III, IV and V step terraces developed in the NW - SE direction. They were formed by the activities of the Ch¶y River during Pleistocene, possibly since the end of Pliocene. The II, I step terraces and river banks are developed in the SW - NE direction, related to the activity of streams formed at the end of Pleistocene. The placer in the II, I step terrace and river banks has usually a richer content of corundum in comparing with the III, IV and V steep terraces, that is caused by the redeposition of older placers, as well as the supply with weathering products of the primary ore bodies.