Mt. Halla, formed through volcanic eruptions, is a shield-shaped volcano.
During the eruptions, lava, because of its low density, flew down slowly,
forming the gentle east and west slopes while the south and north ones remained
steep. A topography formed in this way is geologically referred to as an
htmllite volcano. Mt. Halla takes up the upper part of cone-shaped Jeju Special
Self-Governing Province and is 600m to 1,950m high above sea level.
Mt. Halla was formed through more than 100 volcanic eruptions.
These eruptions also formed parasitic cones or secondary volcanos called
"Oreum" in Jeju dialect. These 368 Oreums are dispersed evewhere on Jeju
Special Self-Governing Province, with Mt. Halla as their center. The
comparatively small place has the most Oreums in the world.
"Oreum refers to a tiny volcanic zone that contains a volcanic
cone, omnipresent at Jeju Island, excluding Paekrokdam at the peak of Hallasan.
It is a typical Jeju dialect that indicates an independent volcanic zone, made
of ejecta or a parasite volcano.
The origin of the word "Oreum" is traced to a noun, made from
the verb "mount," and it is thought to imply a small hill or slope that one can
Jeju Island is a volcanic one, resulting from a series of
volcanic explosions that have occurred not so long ago. The time period for Jeju
Island's geographical origin is presumed to range from 500,000 to 2 million
years ago, a relatively recent event, considering the 4.6- billion- year earth
A parasite volcano is a small volcanic zone and is widespread
around the Hallasan ridges and volcanic piedmont areas, the mountain being
located at the heart of Jeju Island.
Most of the Oreums, Jeju Island's unique parasite volcanos,
were formed out of small sized sporadic volcanic explosions at the Halla
Mountain piedmont areas a few tens and thousands, or even hundreds and thousands
of years ago.