Yangnam Columnar Joints, Gyeongju

On Gyeongju's east coast, between the harbours of Eupcheon and Haseo, the shoreline rocks fan out like an open hand. The Yangnam Columnar Joints bring together basalt columns that stand upright, lean at an angle or lie flat, all on one short stretch of coast. The star is a fan-shaped joint that radiates outwards like the petals of a flower, a form rarely seen elsewhere in Korea. A 1.7 km seaside boardwalk, the Jusangjeolli Padosori-gil ("Sound of the Waves Trail"), takes you past all of them.

How the columns formed

Columnar joints form when hot lava cools and contracts, cracking into hexagonal or pentagonal columns. The columns grow at right angles to the surface through which heat escapes, so where the lava cooled from above and below they stand upright, and where it cooled from the side they lie down. At Yangnam, horizontal columns are unusually widespread, and the radiating fan shape makes the site stand out for both scale and variety.

That makes it a valuable teaching site for how volcanic rock cools, and a useful source for understanding how the East Sea basin formed. The rocks date from the Cenozoic era and were designated a Natural Monument in September 2012.

What to see

• Fan-shaped joint: in the sea directly below the observatory, halfway along the trail. Columns spread out in every direction from a rounded centre, like a flower in full bloom or an open fan.
• Lying, leaning and upright joints: small signs along the path name each type, so they are easy to find. The lying columns, stacked like firewood, are especially striking.
• Columnar Joint Observatory: opened in 2017, with an outdoor viewing deck on the 2nd floor and an indoor viewing room on the 4th. It has displays on local geology and resident geology guides.
• Eupcheon mural village: at one end of the trail, Eupcheon harbour is decorated with 217 murals painted in five competitions between 2010 and 2014.

Tripto tips

• Admission: the trail and the observatory are free. The observatory is closed on Mondays; sources give its hours as 09:00 or 09:30 to 18:00. Check for closures over the Seollal and Chuseok holidays. Tel. +82 54-775-6366.
• Time needed: 30–60 minutes one way along the trail; allow 1.5–2 hours for the round trip and the observatory.
• Getting there: by car, park at Eupcheon harbour public car park; the observatory is about 10 minutes' walk away. By bus, take No. 150 towards Yangnam from Gyeongju Intercity/Express Bus Terminal and get off at the "Jusangjeolli" or "Eupcheon" stop. Buses can be infrequent, so check the timetable.
• Best time: early morning, when the sun rises out of the sea and picks out the texture of the rock. On windy days waves can wash over the boardwalk, so stay off the rocks.
• Combine with: the Underwater Tomb of King Munmu and the Gameunsa Temple Site lie just to the north, making an easy Gyeongju coastal route.