The sandy area called 'Mosewat' near Hallasan Baengnokdam in Jeju will be designated as a natural monument.
The Korea Heritage Service announced on 1st that it plans to designate the 'Hallasan Mosewat Volcano Rock Formation' within the Hallasan Natural Protection Zone in Jeju as a natural monument.
The Hallasan Mosewat Volcano Rock Formation stretches about 2.3 km based on the outer rim of Hallasan, with a maximum width of 500 to 600 m. The name Mosewat combines the Jeju dialect words for sand (mose) and field (wat). The scene of volcanic rocks resembling sand led to its naming.
Here, volcanic rock fragments of varying sizes are widely distributed, interlocking with one another. Volcanic rock, or rhyolite, is a type of volcanic rock that has a high silicon dioxide (SiO₂) content. It is light in color and primarily composed of alkaline feldspar and quartz. The term 'breccia' refers to rock made from angular gravel. It can be easily distinguished from the darker basalt rocks commonly found on Jeju Island.
This area is believed to have formed approximately 28,000 years ago as a result of a small-scale lava dome collapsing (a hill of volcanic rock formed from erupting lava flows). The academic community expects it to be of great help in predicting volcanic disasters or studying the magma eruption process.
Volcanic breccia is the rock formed in the final stage of the process known as magma differentiation, where magma gradually cools and its composition changes. A Korea Heritage Service official noted, "This is the most differentiated form of volcanic rock confirmed in Jeju so far," adding, "The existence of rhyolite rock in Jeju has been confirmed for the first time, making it highly significant."
The Korea Heritage Service plans to finalize the designation of the natural monument after reviewing opinions from various sectors during the 30-day announcement period and going through a review by the Natural Heritage Committee.