Genbudo Cave - Genbudo

This cave is located at the foot of the right bank of the Maruyama River in Toyooka City, northern Hyogo Prefecture. It is a nationally designated natural monument. Volcanic activity occurred in this area at the end of the Pleistocene Epoch (Diluvial Epoch) about 10,000 years ago, and olivine basalt was erupted all over the area. When this cooled, numerous solidification centers were created, which attracted the surrounding magma and solidified, resulting in magnificent columnar joints. These hard hexagonal and octagonal stone pillars were quarried for gardens and stone steps, and over a long period of time the original cliff was hollowed out to form a cave. It was Shibano Ritsuzan, a Confucian scholar from the Edo period who visited the area, who gave it the name Genbudo Cave, and it is from this that the word basalt was translated as basalt after the Meiji period. In addition, there is Seiryu Cave on the right, Byakko Cave and Suzaku Cave on the left. You can get there by bus from Toyooka Station on the JR Sanin Main Line, or by ferry from Genbudo Station on the opposite bank.

[Mamoru Otsuki]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

兵庫県北部、豊岡市(とよおかし)の円山(まるやま)川右岸山麓(さんろく)にある洞窟(どうくつ)。国指定の天然記念物。約1万年前の更新世（洪積世）末にこの付近で火山活動があり、一帯に橄欖石(かんらんせき)玄武岩を噴出した。これが冷却する際、多数の凝固中心線ができ、そこに周辺のマグマが引き寄せられて凝固したため、みごとな柱状節理が生じた。この六角や八角の硬い石柱は、庭園や石段用に採石されたので、もとの絶壁が長い間に掘りくぼめられて洞窟となった。玄武洞と命名したのはこの地を訪れた江戸時代の儒者柴野栗山(しばのりつざん)で、明治以後玄武岩をバサルトbasaltの訳語としたのもこれに由来する。このほか右手に青竜(せいりゅう)洞、左手に白虎(びゃっこ)洞、朱雀(すざく)洞がある。JR山陰本線豊岡駅からバス、または、対岸の玄武洞駅から渡船による。

［大槻　守］

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