Mount Tsukuba - Tsukuba-san

A mountain in western Ibaraki Prefecture. It consists of two peaks, Mt. Nyotai (877m), the main peak, and Mt. Nantai (870m) to the west. It is located in the western mountain range of the Tsukuba mountain range, which forms the southern end of the Yamizo mountain range, and has an elegant mountain shape that juts out into the Kanto Plain. Of the faults that run east and west of Mt. Nyotai, the western fault creates the small flatland of Miyukigahara and the valley of the Minanogawa River between the two peaks. The summit is made of hornblende gabbro, the middle part and below is made of Tsukuba-type granite, and the mountainside is covered with thick deposits of earth and rocks from the collapse of the mountain body. It is said that Mt. Tsukuba was formed as a so-called residual hill, where gabbro trapped in granite resisted erosion and remained. The summit is windy, cool in summer and relatively warm in winter. The middle slope is especially warm in winter, with the temperature inversion occurring. The forest has been protected by Tsukuba-san Shrine since ancient times. The foothills are covered with red pine, the middle slope with fir, and the summit with beech, with a clear distinction between subtropical and temperate forests. The beech forest is a mixture of red oak and star anise, and the forest floor is dominated by bamboo grass such as suzutake. The number of Japanese common toads, famous for the "shiroku toad", has been decreasing in recent years. There are also many native Japanese animals, such as wild boars and raccoon dogs. Hakone salamanders and ancient dragonflies can be seen in the mountain streams, and the beech forest is home to the Ezoharuzemi and Ezozemi, and the foothills are also home to the Himeharuzemi. Many of the forests are sacred grounds for shrines, and forestry is not doing well apart from the use of the red pine at the foot of the mountain. The abundant Tsukuba-type granite has developed into a stonework industry in the Makabe district of Sakuragawa City to the north, where it is used for lanterns, monuments, gravestones and building materials, and in recent years the crushed stone industry has also increased. The western foot of the mountain is also a production area for Shioyaki, which is used to make flower pots and braziers. The mandarin orange cultivation areas, which take advantage of the inversion of temperature, have become tourist orchards. Mount Tsukuba has long been known as a mountain of faith and pleasure, known for its songs of the gods. People have been drawn to the faith of Mount Tsukuba Shrine, which enshrines Izanagi-no-Mikoto (Tsukuba O-o-Okami) and Izanami-no-Mikoto (Tsukuba Me-no-Okami), and the ease of climbing the mountain. Since the opening of the Tsukuba Railway (1918, closed in 1987), cable car (1925) and mountain highway, the area has become a popular tourist destination near Tokyo. It has also been designated as Suigo Tsukuba Quasi-National Park, with roads and tourist facilities such as the Skyline, ropeway and ridgeline forest road. In recent years, the northeast side has been newly developed as Ura-Tsukuba. Academic facilities such as the Earthquake Research Institute of the University of Tokyo are located on the middle slope of Mt. Nantai, and numerous radio relay facilities run by public and private organizations are located near Mt. Nyotai.

[Akitoshi Sakurai]

"The Story of Mount Tsukuba's Gama Oil: The Establishment and Development of the Opening Speech 'Come on, Come on, Come on,'" by Yagi Shinichi (1984, Ronshobo Publishing)" ▽ "The Village at the Foot of Mount Tsukuba" by Inokuchi Shoji (1985, Meishu Publishing)" ▽ "Mount Tsukuba Today: People's Lives and Nature" edited by The Yomiuri Shimbun (1993, Tsukuba Shorin)" ▽ "Mount Tsukuba" by Kimura Shigeru (2000, Tsukuba Shorin)" ▽ "Weekly Japan's 100 Famous Mountains: Asahi Visual Series Mount Tanba, Mount Amagi, Mount Tsukuba" edited and published by The Asahi Shimbun (2001)"

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

茨城県西部にある山。主峰女体山(にょたいさん)（877メートル）とその西の男体山(なんたいさん)（870メートル）の2峰よりなる。八溝(やみぞ)山地南端をなす筑波山塊の西側山列にあり、関東平野に突き出た優美な山容をもつ。女体山の東と西を走る断層のうち西側の断層が両峰の間に御幸原(みゆきがはら)の小平地と男女川(みなのがわ)の渓流をつくる。山頂部は角閃斑糲岩(かくせんはんれいがん)、中腹部以下は筑波型花崗(かこう)岩よりなり、山腹は山体が崩れた土石が厚く堆積(たいせき)している。筑波山の成り立ちは、花崗岩に閉じ込められた斑糲岩が侵食に抵抗して残った、いわゆる残丘であるといわれる。山頂は風が強く、夏は涼しく冬は比較的暖かい。とくに中腹は冬季に気温の逆転現象がおこり温暖である。森林は古くから筑波山神社により保護されてきた。山麓(さんろく)はアカマツ、中腹はモミ、山頂はブナを代表とした林相で覆われ、暖帯林から温帯林までが明瞭(めいりょう)である。ブナ林にはアカガシ、シキミが混生し、林床はスズタケなどのササが多い。「四六(しろく)のガマ」で有名なニホンヒキガエルは近年減少している。イノシシ、タヌキなど日本在来の動物も多い。渓流にはハコネサンショウウオ、ムカシトンボがみられ、ブナ林にはエゾハルゼミ、エゾゼミ、山麓にはヒメハルゼミの発生地もある。森林は神社の神域が多く、山麓のアカマツ利用のほかは林業は振るわない。豊富な筑波型花崗岩は灯籠(とうろう)、碑石、墓石、建築用として北側の桜川(さくらがわ)市真壁(まかべ)町地区に石材業を発達させ、近年は砕石業も増加した。西側山麓では植木鉢、火鉢などをつくる紫尾焼(しいおやき)の産地もある。気温の逆転現象を利用したミカンの栽培地は観光果樹園となった。筑波山は古くから嬥歌(かがい)で知られた信仰と遊楽の山である。伊弉諾尊(いざなぎのみこと)（筑波男大神(おのおおかみ)）・伊弉冉尊(いざなみのみこと)（筑波女大神(めのおおかみ)）を祀(まつ)る筑波山神社の信仰と、登りやすさが、人々を集めた。筑波鉄道（1918。1987年廃止）、ケーブルカー（1925）、登山自動車道などの開通以来、東京近郊の行楽地となり、さらに水郷筑波国定公園(すいごうつくばこくていこうえん)に指定されて、スカイライン、ロープウェー、稜線(りょうせん)林道など道路や観光施設が整った。近年は北東側を裏筑波として新しく開発している。男体山中腹には東京大学地震研究所などの学術的施設、女体山付近には官公署・民間の電波中継施設が多数設置されている。

［櫻井明俊］

『八木心一著『筑波山がまの油物語　口上「さあさあお立ち合い」の成立と展開』（1984・崙書房出版）』▽『井之口章次著『筑波山麓の村』（1985・名著出版）』▽『読売新聞社編『筑波山はいま　人々の暮らしと自然』（1993・筑波書林）』▽『木村繁著『筑波山』（2000・筑波書林）』▽『朝日新聞社編・刊『週刊日本百名山　朝日ビジュアルシリーズ丹波山・天城山・筑波山』（2001）』

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