Miura Peninsula

A peninsula that juts out into the southeastern part of Kanagawa Prefecture. It separates Tokyo Bay from Sagami Bay and faces the Boso Peninsula. Administratively, it is divided into three cities, Yokosuka, Zushi, and Miura, and the town of Hayama. The JR Yokosuka Line, Keikyu Corporation, National Routes 16 and 134, the Yokohama-Yokosuka Road, and the Miura Longitudinal Road run through it, and there is a Tokyo Bay Ferry (regular route) between Kurihama and Kanaya (Boso Peninsula).

The whole area is covered with hilly mountains, with no long rivers or wide plains. Geologically, like the Boso Peninsula, it belongs to the Neogene layer, with the Ookusu Mountains in the center (Ookusu Mountain is 242 meters high) and parallel old landforms and rift valleys, and a flat sea-eroded plateau spreads across Miura City in the south. In terms of climate, the southwestern and southeastern coasts facing Sagami Bay and the Uraga Channel are in the Shonan climate zone, with cool summers and warm winters, while the Tokyo Bay coast is in the Tokyo Bay climate zone.

In ancient times, the Miura Peninsula was the main transportation route (Old Tokaido) that crossed from Sagami Province to the Boso region, and in the Middle Ages, the Miura clan established their estates on the peninsula, and almost the entire peninsula came under the sphere of influence of the Miura clan. It also provided fish supplies and resort areas (Hayama, Misaki, Yokosuka, etc.) for Kamakura, the seat of the shogunate, and was used as an evacuation and refuge site during times of war. During the Edo period, Misaki and Uraga were considered important sea gateways to Edo, and Uraga was a distribution base for maritime goods, with wholesalers gathering there. Uraga and Kurihama are also known as the ports of arrival for American envoys during the late Edo period. After the Meiji period, Yokosuka city became a naval port as a maritime defense base for Tokyo, and military facilities were established throughout the peninsula during World War II.

Currently, Zushi, Hayama and the coast of the Uraga Channel along the coast of Sagami Bay are recreational and residential areas following Shonan. Miura City is a residential area and an early shipping area for vegetables and flowers, as well as a trading area for fresh fish and shellfish at Misaki Fishing Port. Yokosuka City is a defense base, but is also working hard to develop as a commercial and industrial city. In recent years, the peninsula's fishing industry has added many migratory fish, and hiking trails have been opened up in the hills. The Miura Peninsula is being developed into a recreational area for the Keihin megacity cluster, and large areas of green space remain, with the hills of Hayama Town, Okunusanyama and Takeyama designated as special conservation areas for green spaces near the capital region, and coastal landfilling is being strictly controlled.

[Yukio Asaka]

"History of the Miura Peninsula" by Satoru Tanabe (1979, Yokosuka Books Publishing)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

神奈川県の南東部に突出した半島。東京湾と相模湾(さがみわん)とを分け、房総半島に対している。行政上は、横須賀(よこすか)、逗子(ずし)、三浦の3市と葉山町(はやままち)に分かれている。JR横須賀線、京浜急行電鉄、国道16号、134号、横浜横須賀道路、三浦縦貫道路が通り、久里浜(くりはま)と金谷(かなや)（房総半島）との間には東京湾フェリー（定期航路）がある。

　全域に丘陵性の山地が広がり、長い川や広い平野はない。地質上は、房総半島と同じく新第三紀層に属し、中央の大楠山地(おおくすさんち)（大楠山は242メートル）とこれに並行する古い地塁山地と地溝(ちこう)性の谷がみられ、南の三浦市には平坦(へいたん)な海食台地が広がっている。気候は、相模湾と浦賀水道に臨む南西と南東の沿岸は夏涼冬暖の湘南(しょうなん)気候区に入れられ、東京湾岸は東京湾気候区に入れられる。

　古代には、三浦半島には相模国から房総地方へ渡る幹線交通路（古東海道）が開け、中世には三浦氏の荘園(しょうえん)が開かれ、半島のほとんど全域が三浦党の勢力圏となっていた。そして幕府の所在地鎌倉の魚類供給や保養地（葉山、三崎(みさき)、横須賀など）となり、戦乱時には疎開、避難の場所にも利用されていた。江戸時代には三崎と浦賀は江戸の海の関門として重要視され、浦賀には問屋が集まって海上輸送物資の流通基地ともなっていた。浦賀、久里浜は幕末期のアメリカ使節の来航地としても知られる。明治以後、横須賀市は東京の海上防衛基地として軍港となり、第二次世界大戦中には半島全域にわたって軍の諸施設が設けられた。

　現在、相模湾岸の逗子、葉山や浦賀水道沿岸は、湘南に続く休養地域、住宅地域となっている。三浦市は三崎漁港の生鮮魚貝の取引のほか、野菜や草花の早期出荷地域、住宅地域となっている。横須賀市は防衛基地となっているが、商工業都市としての発展にも力を注いでいる。近年、半島の漁業は回遊魚を多く加えており、丘陵にはハイキングコースが開けている。三浦半島では京浜巨大都市群向けのレクリエーション地域化が進められ、また、緑地が広く残り、葉山町の丘陵地や大楠山、武山(たけやま)などは首都圏近郊緑地特別保全地区に指定され、海岸の埋立ても強く抑制されている。

［浅香幸雄］

『田辺悟著『三浦半島の歴史』（1979・横須賀書籍出版）』

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