Guraigol (Hantangang River UNESCO Global Geopark)

Guraigol is a compound word of gul (cave) + awi (rock), also called Gulbawi (cave rock). It was named because the gorge looks like a cave in summer when the vegetation is lush. Guraigol is a small basalt gorge formed in a tributary of the Hantangang River, and is one of the places where three lava flows with different cooling processes can be well observed.<br /><br />The uppermost part is about 5 m thick, lacks columnar joints, and is characterized by massive fracturing. Additionally, a weak clinker layer is developed at the bottom. In the middle-lower part, cylindrical separation structures are well observed, indicating relatively slow cooling. It is divided into upper, middle, and lower parts based on the presence and characteristics of columnar joints.<br /><br />In the lower and middle parts, columnar joints are well developed; the lower part is relatively larger and more irregular than the middle part, while the middle part has regularly developed columnar joints with a diameter of 20–30 cm. In the uppermost part of the upper section, 2–3 layers of lava crust are observed, and columnar joints are developed below them, but their diameter is larger than those in the middle part.<br /><br /><Source: Hantangang River Geopark>