The is divided into two distinct rock formations on either side: the Beinanshan conglomerate on one side and the Liji Melange on the other. Both were uplifted by by the collision of the Eurasian and Philippine Sea plates, but their properties differ. The Beinanshan conglomerate is an alluvial deposit of the Central Mountain Range, with low cementation, making it easily eroded by rainwater, forming isolated small peaks, similar to Huangshan Mountain in mainland China, hence the name "Little Huangshan." The Liji Melange is deep-sea sedimentary mudstone with very fine grains and low permeability. After rain, a layer is washed away, forming trenches, making it impossible for plants to grow, hence the term "Badlands." During the uplift, basalt, gabbro, and peridotite from the ophiolite system of the marine plate were also brought up. These are unrelated to the mudstone and are therefore called foreign rocks.