Kitamukidani Primeval Forest

...The river originates near the junction of Mt. Nekodake (1,408m) and the southern outer rim of Mt. Aso, flows west through Nangou Valley, collecting spring water along the way to increase its volume, and flows over the Ayugaeshi Falls near Tochigi before entering a gorge, merging with the Kurokawa River from the Aso Valley at Toshita, where it cuts through the outer rim wall and carves a deep V-shaped valley at the Tateno Crater Rapids. On the left bank in this area is the Kitamukidani primeval forest (Ten), which is mainly composed of evergreen broad-leaved forests. From here, it cuts through the alluvial plateau of the Kumamoto Plain in an almost straight line and flows west, meandering through the middle and lower reaches of Kumamoto city before entering Shimabara Bay.

*Some of the terms mentioned in the "Kitamukidani Primeval Forest" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…源を根子（ねこ）岳(1408m)と阿蘇の南外輪山のすそ合い付近に発し，南郷谷を西流して，途中湧水を集めて水量を増し，栃木（とちのき）付近で鮎返滝を掛けたのち峡谷に入り，戸下（とした）で阿蘇谷からの黒川と合流，外輪壁を破る立野（たての）火口瀬で深いV字谷を刻む。この付近の左岸には照葉樹林を主とした北向谷（きたむきだに）原始林(天)がある。これより熊本平野の洪積台地をほぼ一直線に割って西流，中･下流を蛇行しながら熊本市街を貫流し島原湾に入る。…

※「北向谷原始林」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報