This area is the ending range of Dabie Mountain with an area of 4.458 million mu, accounting for 16.5% of the total area of Lu'an. The altitude is between 100 and 400 meters above sea level. The land is of gentle rolling hills and open basins, consisting of mainly purple sandstone, grained sandstone and conglomerate. The slope is less than 25 degree, only few slopes larger than 25 degree.