Columnar Joint in Daljeon-ri, Pohang

Columnar joints are rock formations that split regularly into column shapes; they form when, under pressure changes caused by crustal movement, folding, weathering and surface erosion, magma pushes up through cracks in surface rock. This example developed in basalt that erupted at the end of the Tertiary period of the Cenozoic era, about 2 million years ago. The columnar joints of Daljeon-ri, Pohang were discovered during the development of a quarry. They measure about 20m in height and some 100m in length. The joints are generally hexagonal in cross-section, and the columns show an unusual curve, tilting at about 80 degrees near the base and bending to a nearly horizontal angle higher up. This is because the erupted lava, after rising from underground to the surface, then flowed horizontally near the surface. The columnar joints of Daljeon-ri, Pohang are well developed and have an unusual orientation, giving them high geomorphological and geological value, and they are also of great value as a site for outdoor scientific study.

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Where it is

Region

Pohang, Gyeongbuk

Designation

Natural Monument · 천연기념물