Both Jingtong and Shifen areas are famous places of coal mining in Taiwan a hundred years ago.An investigation found that the "waste rock mountains",which were formed as coal gangue was piled-up,are almost firm and solid in Jingtong mining area,but the "waste rock mound",which was formed as solid wastes was discarded at random by the riverside,is easy to collapse in Shifen mining area.To probe into the man-made geomorphology,we find that the Taiyang Mining Corporation in Jingtong made thought-out plans to choose better location.Contrarily,other small mining enterprises in Shifen might decide excursive policies which accounted for small disasters every so often.Consequently,the local administration would program the abandoned waste rock mountains in the mining areas as leisure and recreation sites for inhabitants,because of the safe discharge mode of coal gangue.