Ping Chau
Ping Chau is unique in the fact that it is the only sizeable island in Hong Kong made up of sedimentary rock. Hong Kong is mostly formed of extrusive igneous rocks, after a series of major volcanoes erupted during the Jurassic Period. Following the volcanic activity, a basin formed in the northeast, with deposition in a brackish lake—producing the siltstones and chert of Tung Ping Chau, which have been dated from the early Paleogene period. It is also home to some spectacular cliffs and wave-cut platforms. Landforms such as these are very rarely found in the rest of Hong Kong.