() is at the western end of the Sobo Mountain range 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 ...

. It is now part of 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, ) ...

Formation

It is believed that the foundation of the Sobo mountain range occurred in two periods of volcanic activity. The first, around 13 million years ago, was buried in the second period of volcanic activity ending about 10 million years ago leaving the landscape seen today. The extinct Katamukiyama Caldera is aligned on a NW to SE axis and was by in size with a DRE erupted volume of .Daisuke, Miura; Yutaka, Wada (2007)
"Middle Miocene ash-flow calderas at the compressive margin of southwest Japan arc: Review and synthesis". ''The Journal of the Geological Society of Japan''. 113 (7): 283–295. doi:10.5575/geosoc.113.283
Retrieved 8 August 2019. From about 3 million years ago the activity of the Aso volcano caused nearby pyroclastic flow deposition.

Environment

The slopes of 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 hemlock. 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.

References

Mountains of Ōita Prefecture {{Asia-mountain-stub