Manjanggul Lava Tube

At last after passing the signboard numerous times, now tickets in the hand Manjanggul cave is becoming a reality.  Manjanggul lava tube is located in Gimnyeong-ri close to Jeju City.  The cave is 7.4 kilometres long with a multi-level structure. The main passage has a width of roughly 18 metres and a height of up to 23 metres.


The passage shape and internal micro topographical features are in good nick despite its age.  The entrances to the cave were created naturally by the collapsing of the ceiling.  The formations to expect in the cave are lava stalactites, lava stalagmites, flowlines, lave benches, lava rafts, and a lava column of about 7.6 metres in height.

Lava Flowlines

When lava flows in a tube, the level of the flow is often recorded on the walls.  These features are called lava flowlines.  Numerous flowlines are visible, indicating the level of the lava flows was falling continuously inside the active tube.

Lava Stalactites

As lava flows through a lava tube, the ceiling partially melts due to the high temperature, oozing down and forming a solid speleothem called a lava stalactite, which can be classified into shark tooth stalactites, tubular lava stalactites, and splash stalactites depending on the shape.  When lava drips from stalactites to the floor regularly, it forms lava stalagmites.  Lava stalactites are more commonly found in narrower and lower passages.

Large and Small Passages

There occur large and small passages repetitively.  A continuous supply of hot lava into the tube causes thermal erosion of the tube's floor whereas the lava can be accreted on the tube ceiling, resulting in the irregular height of the tube.  Near narrow passages, Manjanggul opens up into a section with wider and higher ceilings. The dome-like topography of this ceiling is called a "cupola".

Rock Falls

There is quite an abundance of rock fragments that fell from the ceiling scattered throughout the lava tubes.

Lava Raft

A lava raft is formed when rock fragments from the ceiling or sidewall fall during lava flow and then are carried away by lava before settling and solidifying.  In some cases, fallen rocks are completely coated by lava to form mound-like or ball-like lava rafts, which are called lava balls.

Turtle Rock

The lava raft named Turtle Rock, which carries a strong resemblance to Jeju Island became the symbol of Manjanggul Lava Tube. Unlike the formation of normal lava raft, Turtle Rock formed by accretion of hot lava along the margin of a fallen rock after it was settled on the floor.  The flowlines along the margin of Turtle Rock coincide with those on the wall.

Quartzite Fragments

Most rockfall debris consists of basaltic rocks but also comprises light-coloured rocs, called quartzite, distinguishable from basalt.  These rock fragments, ranging between 1 to 5 cm in size, are interpreted to have been derived from the metamorphic basement tocks and then incorporated into the lava flow.

Lava Shelves

Lava shelves form when the liquid lava, only partially filling the tube, is accreted and hardened on the cooler walls. Lava shelves are further divided into lava balconies and lava benches according to their shapes.

Lava Toe

Lava toes formed when the lava flowing through the upper-level to poured down through a floor opening. The poured-down lava flowed in a series of elongate and entangled lava lobes, each of which is reminiscent of an elephant toe, giving it its name.

Lava Flowstones

Lava flowstones form as the heat of lava melts the ceiling and the walls inside a lava tube. The melted lava flows down the walls and takes on various sizes and shapes depending on the temperature and amount of lava. Lava flowstones also form when liquid lava inside the wall seeps out through small holes.

Lava Column

Lava columns form when lava pours down from the ceiling to the floor and congeals. The lava column in this cave is 7.6 metres high making it the largest one in the world. The lava poured down from the ceiling spread across the floor of the lower passage and made well-developed lava toes.