Typical coastal terrain–Basalt Island

Typical coastal terrain–Basalt Island

Background Information

Basalt Island is an island south of Town Island (Fo Tau Fan Chau) and Wang Chau, east of Bluff Island (Sha Tong Hau Shan) and north of the Ninepins. Only 174 metres at its highest point, it was the site of an air disaster in 1948. An aircraft coming into Hong Kong from Shanghai crashed on the island, killing all 30 crew members and passengers. Sixty years have since passed and all traces have been erased by swells and typhoons. Only an air disaster monument remains on the island to recall this tragic accident.

Geological Information

Like Bluff Island and Wan Chau, the outcropped stratum of Basalt Island is part of the Early Cretaceous Kau Sai Chau Volcanic Group. The island has very well developed sea stacks, island reefs and wave-cut bays which clearly demonstrate the impacts of wave erosion on the environs. Waves, in forms of erosion, abrasion and dissolution, cause devastating damage to the shores. Given that the Kau Sai Chau Volcanic Group is full of columnar joints and fissures, impacts of pounding waves on rocks are particularly obvious. Meanwhile, continuous abrasion by sand and gravel carried by waves has brought changes to the shores and submerged bedrock, sculpting an amazing array of precipitous cliffs and spectacular landforms. In geology, wave cut action is one example of exogenous effect. The islands and wave-cut terrains in the Basalt Island region are excellent showcases that reveal how of this geological process modified geomorphology.