Tanzawa Mountains - Tanzawasanchi

A mountain range in the northwest of Kanagawa Prefecture. In a broad sense it is included in the Kanto Mountains, but is generally considered an independent mountain range and is also called the Tanzawa Mountains. It is separated from the main part of the Kanto Mountains by the Katsura River (upstream of the Sagami River), and is bounded on the east by the Sagami River, on the south by the Odakyu Electric Railway Line and the JR Gotemba Line, and in the west it reaches south of Lake Yamanaka. It stretches about 40 kilometers east to west and about 30 kilometers north to south. The highest peak, Hirugatake, is 1,673 meters. It is a folded mountain range formed as a result of a large uplift movement in the Tertiary Period of geological time, and is accompanied by complex faults, which caused many landslides and cliff collapses during the Great Kanto Earthquake.

The topography differs dramatically between the inside and outside of the 600-meter contour line. The inside is steep and forms the main mountain range, with a group of main peaks in the center, including Hirugatake, Tanzawayama (1,567 meters), Togatake (1,491 meters), and Oyama (1,252 meters). The ridgeline stretches 800 to 1,000 meters from these peaks, and is broad and flat with rounded edges. However, the valleys are steep and deep, with many waterfalls and rock collapses. Above 700 to 800 meters, broadleaf forests, mainly consisting of tall trees such as beech, oak, and himeshara, have developed. The ridgeline of the main peaks from Hinokiboramaru (1,601m) in the northwest to the various peaks in the center and Mt. Daisen is a humid and foggy environment, with large maple and beech trees growing in clusters, creating a wonderful landscape. Mt. Daisen and Mt. Togatake have also been revered as sacred mountains since ancient times, and there are many ruins related to mountain worship on the ridgeline, mid-mountain, and foothills. The outer part is a low mountain of 400 to 500m, which forms the front mountain surrounding the main body. It is further divided into the Nakatsu Mountains in the east, the Doshi Mountains in the north, and the Ashigara Mountains in the southwest. The Nakatsu Mountains in particular are a good example of a stepped fault topography, with a parallel fault running north-south, which descends in a stepped manner to the east. These are covered with large artificial cedar and cypress forests, but natural mountain dogwood and beech forests also remain.

The Tanzawa Mountains are also home to many deer, wild boars, Japanese macaques, Japanese serows, as well as many birds, butterflies, and insects. The main part of the mountain range is designated as Tanzawa-Oyama National Park, and the western edge is designated as the Prefectural Tanzawa-Oyama Natural Park.

[Yukio Asaka]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

神奈川県の北西部にある山地。広い意味では関東山地に含まれるが、一般には独立した山地とされ、丹沢山塊ともよばれる。桂(かつら)川（相模(さがみ)川の上流）によって関東山地の主部と区分され、東側は相模川、南側は小田急電鉄線とJR御殿場(ごてんば)線でくぎられ、西は山中湖の南に及んでいる。東西約40キロメートル、南北約30キロメートルにわたる。最高の蛭ヶ岳(ひるがたけ)は1673メートル。地質時代第三紀の大きな隆起運動に伴ってできた褶曲(しゅうきょく)山地で、複雑な断層を伴い、関東大震災には多くの地すべりや崖崩(がけくず)れをおこした。

　ほぼ600メートルの等高線を境として、その内側と外側では地形が著しく異なっている。内側は急峻(きゅうしゅん)で山地の本体をなし、その中央に蛭ヶ岳、丹沢山（1567メートル）、塔ヶ岳(とうがたけ)（1491メートル）、大山(おおやま)（1252メートル）などの主峰群がある。これらの主峰から800～1000メートルにわたる稜線(りょうせん)部には、丸みをもった広い平坦(へいたん)面が発達している。しかし、谷は急斜面で深く、滝が多く、岩石の崩れも多い。700～800メートル以上は、ブナ、ミズナラ、ヒメシャラなどの高木を主とした広葉樹林が発達している。そして北西の檜洞丸(ひのきぼらまる)（1601メートル）から中央部の諸峰、大山にかけた主峰群の稜線一帯は霧の多い多湿環境で、オオモミジガサやブナが群生していてすばらしい景観をなしている。また、大山や塔ヶ岳は古くから神体山として崇(あが)められ、稜線、中腹、山麓(さんろく)の諸所に山岳信仰関係の遺跡が少なくない。外側は400～500メートルの低山で、本体を取り巻く前山をなしている。それはさらに東部の中津山地、北部の道志山地(どうしさんち)、南西の足柄山地(あしがらさんち)に分けられ、ことに中津山地は南北方向の並行断層で、東方へ階段状に低下しており、階段断層地形の好例をなしている。これらには人工のスギ・ヒノキ林が広いが、天然のヤマボウシやブナ林も残っている。

　丹沢山地はまた、シカ、イノシシ、ニホンザル、ニホンカモシカをはじめ、多くの鳥類やチョウ類そのほか昆虫類の生息が多い。山地の主要部は丹沢大山国定公園(たんざわおおやまこくていこうえん)に、また西辺は県立丹沢大山自然公園に指定されている。

［浅香幸雄］

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