Columnar Joint Landscape

This is a lava landscape. During the cooling of homogeneous magma, columnar joints form due to even cooling and contraction and split the rock into regular hexagonal and pentagonal columns, which are called volcanic columns. These columns are perpendicular to the cooling surface of the molten body (i.e., perpendicular to the lava surface or the rock neck contact surface). Columnar joints are very common in basalt. Typical examples are Niutou Mountain and Nandian Island in Zhangzhou Littoral Volcano National Geopark, Fujian Province, Liuheguizi Mountain in Nanjing, Penghu, and the Giant’s Causeway in Ireland. Columnar joints can also develop in rhyolitic volcanic rocks, such as in the Hong Kong Global Geopark in Sai Kung, Hong Kong, Taozhu National Geopark in Linhai, Zhejiang Province, and Hua’ao Island in Xiangshan, Ningbo City (Fig. 43).

Fig. 43

Columnar joints in Liuhe National Geopark, Nanjing