is one of the

100 Famous Japanese Mountains is a book written in 1964 by Mountaineering, mountaineer and author Kyūya Fukada.Hyakumeizan, Hiking Japan ...

. The mountain lies on the border of Taketa and Bungo-ōno in

Ōita Prefecture is a prefecture of Japan located on the island of Kyūshū. Ōita Prefecture has a population of 1,081,646 (1 February 2025) and has a geographic area of 6,340 km2 (2,448 sq mi). Ōita Prefecture borders Fukuoka Prefecture to the northwest, K ...

and

Takachiho file:TakachihokyoWithManaiFalls.JPG, 270px, Manai Falls file:Mt.Sobo.jpg, 270px, Mount Sobo file:Yokagura.jpg, 270px, Yokagura is a List of towns in Japan, town in Nishiusuki District, Miyazaki, Nishiusuki District, Miyazaki Prefecture, Japan. , t ...

, Nishiusuki District in

Miyazaki Prefecture is a Prefectures of Japan, prefecture of Japan located on the island of Kyūshū. Miyazaki Prefecture has a population of 1,028,215 as of 1 January 2025 and has a geographic area of 7,735 Square kilometre, km2 (2,986 sq mi). Miyazaki Prefectur ...

. It is within the

Sobo, Katamuki and Okue Biosphere Reserve The Sobo, Katamuki and Okue Biosphere Reserve also known as was created in 2017. It incorporates the 1965 quasi national parks of Sobo Katamuki Prefectural Natural Park (Ōita) (also previously known as the Sobo-Katamuki Quasi-National Park, ) ...

. Mount Sobo is the highest peak in Miyazaki Prefecture and in Ōita Prefecture only the middle peak of

Mount Kujū , located on the border of Kokonoe and Taketa in Ōita Prefecture, Japan, is a stratovolcano in Kyushu Island, Japan, with a summit elevation of . It is one of the 100 Famous Japanese Mountains. It is part of the Aso-Kujū National Park. S ...

is higher. The Sobo Mountain range extends into three prefectures: Ōita, Miyazaki and

Kumamoto is the capital Cities of Japan, city of Kumamoto Prefecture on the island of Kyushu, Japan. , the city has an estimated population of 738,907 and a population density of 1,893 people per km2. The total area is 390.32 km2. had a populat ...

. Because of the volcanic activity which formed the mountain, huge rocks can be found everywhere around the mountain. There is a great variety of mountain climbing routes, ranging from animal trails to well maintained paths. Courses ae available from relaxed

hiking A hike is a long, vigorous walk, usually on trails or footpaths in the countryside. Walking for pleasure developed in Europe during the eighteenth century. Long hikes as part of a religious pilgrimage have existed for a much longer time. "Hi ...

for enjoyment to cliff climbing routes aimed at advanced climbers. Steep rock climbing routes can be seen from all trails in the neighbourhood of the summit. The surroundings of Mount Sobo abound in mineral resources which were mined from the

Edo period The , also known as the , is the period between 1600 or 1603 and 1868 in the history of Japan, when the country was under the rule of the Tokugawa shogunate and some 300 regional ''daimyo'', or feudal lords. Emerging from the chaos of the Sengok ...

to the mid-

Shōwa period Shōwa most commonly refers to: * Hirohito (1901–1989), the 124th Emperor of Japan, known posthumously as Emperor Shōwa ** Shōwa era (昭和), the era of Hirohito from 1926 to 1989 * Showa Corporation, a Japanese suspension and shock manufactu ...

Formation

It is believed that the foundation of the Sobo mountain range occurred in two periods of volcanic activity. In the first period, around 13 million years ago, two cauldrons, the ''Sobo

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

'' and the , were formed in an

eruption A volcanic eruption occurs when material is expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has ...

accompanied by

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...

. The two cauldrons formed at this time, were buried in the second period of volcanic activity leaving the caldera which can be seen today. About 12.5 million years ago, a cauldron opened up once more. During this time

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

was formed. Around 10 million years ago the volcanic activity ceased. Erosion levelled off the mountain until 3 million years ago when the large scale activity of the rising

Mount Aso or Aso Volcano is the largest active volcano in Japan and among the largest in the world. Common use relates often only to the somma volcano in the centre of Aso Caldera. It stands in Aso Kujū National Park in Kumamoto Prefecture, on the i ...

system caused a pyroclastic flow which gave Mount Sobo its present shape.

Environment

Thanks to volcanic activity,

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

is ubiquitous. In the valleys at the bottom of the mountain and at medium and high altitude rock-climbing fans are fascinated by the cliffs which can be found everywhere. Miyama Kirishima (''

Rhododendron kiusianum ''Rhododendron kiusianum'', the Kyushu azalea, is a species of flowering plant in the family Ericaceae, native to Kyushu, Japan. It is a parent of a large number of hybrid dwarf azaleas, drawn from the naturally-occurring Kurume azaleas used in ...

''), Japanese gentian and the

Japanese maple ''Acer palmatum'', commonly known as Japanese maple, palmate maple, or smooth Japanese maple (Korean: ''danpungnamu'' []; Japanese: ''irohamomiji'' [] or ''momiji'' []), is a species of woody plant native to Korea, Japan, China, eastern Mongol ...

grow in great numbers and are visited by mountain climbers in all seasons.

Flora

The mountain is covered by

old-growth forest An old-growth forest or primary forest is a forest that has developed over a long period of time without disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of the United Natio ...

. Typical species include

Japanese beech The name Japanese beech can refer to two different species of beech tree, both native to Japan. *''Fagus crenata'', also called Siebold's beech, (, in Japanese) *''Fagus japonica ''Fagus japonica'', known as the Japanese beech, Japanese blue b ...

and ''

Tsuga ''Tsuga'' (, from Japanese (), the name of '' Tsuga sieboldii'') is a genus of conifers in the subfamily Abietoideae of Pinaceae, the pine family. The English-language common name "hemlock" arose from a perceived similarity in the smell of it ...

''. Going up from the lowland, the vegetation changes from evergreen (glossy-leaved) forest over

conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...

forest halfway up the mountain, to Suzu-take and beech close to the summit. ''

Angelica ubatakensis ''Angelica'' is a genus of about 90 species of tall Biennial plant, biennial and Perennial plant, perennial herbaceous, herbs in the family Apiaceae, native to temperate and subarctic regions of the Northern Hemisphere, reaching as far north as ...

'' is only found on parts of

Shikoku is the smallest of the List of islands of Japan#Main islands, four main islands of Japan. It is long and between at its widest. It has a population of 3.8 million, the least populated of Japan's four main islands. It is south of Honshu ...

and in the Sobo mountain range is a precious plant. The pseudonym of Mount Sobo, (''uba'' meaning "elderly woman" in Japanese), goes back to the discoverer of the plant,

Tomitaro Makino was a pioneer Japanese botanist noted for his taxonomic work. He has been called "Father of Japanese Botany", having been one of the first Japanese botanists to work extensively on classifying Japanese plants using the system developed by Carl ...

, who called it that.

Fauna

It is thought that the southern range limit of the , the

Japanese serow The (''Capricornis crispus'') ( 羚羊) is a Japanese goat-antelope, an even-toed ungulate. It is found in dense woodland in Japan, primarily in northern and central Honshu. The serow is seen as a national symbol of Japan, and is subject to p ...

lies in the mountain range. Even though sightings have been rare in recent years, the

Asian black bear The Asian black bear (''Ursus thibetanus''), also known as the Asiatic black bear, moon bear and white-chested bear, is a medium-sized bear species native to Asia that is largely adapted to an arboreal lifestyle. It is distributed from southeast ...

is believed to be living here as well. In addition Japanese dormice and

sika deer The sika deer (''Cervus nippon''), also known as the northern spotted deer or the Japanese deer, is a species of deer native to much of East Asia and introduced to other parts of the world. Previously found from northern Vietnam in the south t ...

can be seen.

Mining

At the foot of Mount Sobo lie the remains of the Obira mine. From its opening in 1617 until its closing in 1954, it had been flourishing as the leading Japanese mine. Apart from Obira, there are the and the on the side of Ōita Prefecture as well as the and on the side of Miyazaki Prefecture. The mines produce scarce minerals like

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

tin Tin is a chemical element; it has symbol Sn () and atomic number 50. A silvery-colored metal, tin is soft enough to be cut with little force, and a bar of tin can be bent by hand with little effort. When bent, a bar of tin makes a sound, the ...

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

and

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

History

On August 30, 1945, a

B-29 Superfortress The Boeing B-29 Superfortress is a retired American four-engined Propeller (aeronautics), propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to ...

of the

United States Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

on a supply flight crashed in bad weather in the neighbourhood of located south of Mount Sobo. All twelve crew members died in the incident. Part of the

fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...

and the Stars and Stripes still lie among the mountains. A ''Prayer for Peace'' monument was erected on August 26, 1995 to commemorate this event.

References

External links

Topographic map
{{DEFAULTSORT:Sobo, Mount Mountains of Ōita Prefecture Mountains of Miyazaki Prefecture