Hantangang River Geopark

Auraji means the estuary where two or more waterways gather together and pillow lava was named because basalt looks like a round pillow.
Pocheon Auraji pillow lava is a geological attraction located at the mouth of the river where the Hantan River and Yeongpyeongcheon meet and is a rock hardened while hot lava was flowing and quickly cooled in cold water(Yeongpyeongcheon). This pillow lava is hardly found in the land and most are formed in the water-rich sea.

Looking at the cross section of pillow lava, you can see a molar shape due to the developed its concentric structure and radial joints. It appears as a circle or oval of 50~100cm in diameter and surface is cooled rapidly, consisting of glassiness with a thickness of 1 ~ 2cm (Won Jong-gwan et al, 2010).