On the both sides of the mouth of Phohang Stream, there is a cliff formed with solid quartzite layers of methoproterozoic Jikhyon group along the coastline. An abrasion platform was formed at the foot of the cliff washed by waters.

Ceaselessly washed by waves, lumps of quartzite turned into smooth and oval yellowish stones. The ball-stones are used for decorating buildings.

The natural round stones, rare to be seen elsewhere in the world, are one of the natural wonders in the DPRK.