Mount Tanigawa

It is one of the peaks in the Mikuni Mountain Range on the border between Gunma and Niigata prefectures. Its summit is divided into two peaks, Toma-no-mimi (1,963 meters) and Oki-no-mimi (1,977 meters), and has long been called "two ears." It belongs to Joshin'etsu-kogen National Park. The 2,000-meter-class mountains, centered around Tanigawadake, stretch from Shimizu Pass in the north to Mikuni Pass in the west, and are collectively called the Tanigawa Mountain Range. These mountains are mainly composed of green tuff from the Tertiary layer, which runs through it, and granite, quartz diorite, serpentine, etc., and in some places there is hard rock such as hornfels. Located on the mountain range that borders the Pacific and Sea of ​​Japan sides of the country, it is subject to strong erosion from snowfall, heavy rain, and strong winds, and the differences in the resistance of the rocks to erosion have resulted in the complex and rugged topography of its mature years. The hard rocks on the eastern slope in particular form cliffs, and Machigasawa, Ichinokurasawa, and Yunosawa are some of the largest rock formations in Japan, making climbing extremely difficult. Additionally, the Zange Rock on the southeastern slope shows signs of wear, and small cirque-like topography can be seen near the summits of the eastern and southern slopes, reminiscent of erosion from the Ice Age. The forest limit is about 1,500 meters above sea level.

The appeal of Mt. Tanigawa lies in its steep mountain shape and the view, but it became famous after the opening of the JNR (now JR) Joetsu Line in 1931 (Showa 6), which led to a dramatic increase in the number of climbers from the Tokyo area. The main trailhead is Doai Station (underground station) on the Joetsu Line, with others at Tsuchitaru and Tanigawa Onsen. In 1960 (Showa 35), a ropeway was installed from Doai to Tenjindai at an altitude of 1,320 meters, and the national Tenjindai Ski Resort was also built, attracting a larger number of climbers and gradually making it into a tourist destination. However, the weather is prone to sudden changes, and there are also avalanches, thick fog, and heavy rains, and many people have been lost on the mountain, especially from falls while climbing rocks, so it is also called "the devil's Mt. Tanigawa." In 1967, Gunma Prefecture enacted the Tanigawadake Disaster Prevention Ordinance, which required mountain climbers to notify the danger zones of Ichinokurazawa, Yuunosawa, and Machigasawa, excluding the general routes such as the Nishikuroone course. The Governor of Gunma Prefecture prohibits climbing on days with bad weather, and the Tanigawadake Mountaineering Guidance Center has been established at the Doaiguchi entrance to provide guidance on how to prevent accidents and climb safely, and security guards are also stationed, in an effort to reduce the number of accidents. Nevertheless, according to a survey by the Gunma Prefecture Tourism Division, 693 people died in mountain accidents in the 50 years from 1931 to 1981 (Showa 6-56), an average of 13.9 people per year. After that, the number of deaths decreased, and in the 20 years from 1982 to 2001 (Heisei 13), it was 78 people, an average of 3.9 people per year (a total of 771 people since 1931, 779 including missing people). A memorial tower and monument have been erected near National Route 291 at Doaiguchi, and the names and prefectures of those who have died since 1931 are inscribed on the monument.

[Murakami Sadao]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

群馬・新潟県境にある三国山脈(みくにさんみゃく)の一峰。頂上はトマの耳（1963メートル）、オキの耳（1977メートル）の2峰に分かれ、古くから「耳二つ」とよばれた。上信越高原国立公園に属する。2000メートル級の山々が谷川岳を中心に北の清水峠(しみずとうげ)から西の三国峠の間に連なり、これを総称して谷川連峰という。これらの山々は、おもに第三紀層の緑色凝灰岩とそれを貫く花崗(かこう)岩、石英閃緑(せんりょく)岩、蛇紋(じゃもん)岩などからなり、部分的にはホルンフェルスの硬い岩石もある。日本の太平洋側と日本海側の境界の脊梁(せきりょう)山脈にあるため、積雪と豪雨、強風などで侵食作用が強く、しかも侵食に対する岩石の抵抗力の相違から、複雑で険しい壮年期の地形を現している。とくに東斜面の硬い岩石は岩壁をなし、マチガ沢、一ノ倉(いちのくら)沢、幽(ゆう)ノ沢などは日本屈指の規模をもつ岩場で、登山はきわめて困難である。また、南東斜面のザンゲ岩には岩盤に擦痕(さっこん)がみられ、東斜面と南斜面の山頂付近には小型の圏谷に似た地形も認められて氷河時代の侵食を思わせる。森林の限界は標高1500メートルぐらいである。

　谷川岳の魅力はこのような峻険(しゅんけん)な山容と展望にあるが、有名になったのは1931年（昭和6）国鉄（現、JR）上越線開通以後、東京方面からの登山者が激増したからである。おもな登山口には、上越線土合(どあい)駅（地下駅）を主登山口に、ほかに土樽(つちたる)口、谷川温泉口などがある。1960年（昭和35）には土合口から標高1320メートルの天神平(てんじんだいら)までロープウェーが設けられ、国設天神平スキー場もできて、登山者層が厚くなり、しだいに観光地の性格も帯びてきた。しかし、天候が激変しやすく雪崩(なだれ)や濃霧、豪雨の襲来もあり、登山とくに岩登りによる転落などで多くの遭難者を出し「魔の谷川岳」ともいわれる。そこで、1967年群馬県は谷川岳遭難防止条例を制定、西黒尾根(にしくろおね)コースなどの一般コースを除いて、一ノ倉沢、幽ノ沢、マチガ沢などの危険指定地域を登山届出制にした。悪天候の日には群馬県知事が登山を禁止し、また土合口に谷川岳登山指導センターを設けて遭難防止と安全登山を指導し、また警備隊を配置するなどして遭難事故の減少に努めている。それでも群馬県観光課の調査によると、1931～1981年（昭和6～56）の50年間に693人が遭難死し、年平均13.9人となった。その後、遭難死の数は減少し、1982年から2001年（平成13）までの20年間では78人、年平均3.9人となっている（1931年からの合計771人、行方不明者を含めると779人）。土合口の国道291号のそばに慰霊塔と碑が建てられ、碑には1931年以降の死亡者の氏名と都県名が刻してある。

［村木定雄］

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