Joso Plateau - Joso Plateau

Located in the eastern part of the Kanto region, this plateau is rich in flatland forests and straddles Ibaraki and Chiba prefectures across the Tone River lowlands. It is made up of the Hitachi Plateau on the Ibaraki side and the Shimousa Plateau on the Chiba side. Influenced by the Kanto Tectonic Basin Movement, it is lowest at about 15 meters near Koga City, Ibaraki Prefecture, which is in the center of the Kanto Plain, and increases in elevation toward the surrounding areas, reaching 40 meters in Chikusei City and Kashima City in Ibaraki Prefecture, 40 meters near Katori City in Chiba Prefecture, and 50 meters near Sanmu City in the same prefecture. The geology is mainly the Narita Formation, which contains gravel and clay, and is topped by the Kanto Loam Formation. The plateau surface is wide, corresponding to the Musashino surface on the Hitachi Plateau and the Shimosueyoshi surface on the Shimousa Plateau. The Hitachi Plateau is further divided by its many rivers into various plateaus, including Naka, Kashima, Ibaraki, Tsukuba, Inashiki, Yuki, and Sashima. The Shimousa Plateau was used as a pasture for horses in the early modern period, and is now the largest producer of peanuts in Japan, as well as a large producer of suburban vegetables. The area is also becoming a residential suburb of Tokyo, with Narita City, home to Naritasan Shinshoji Temple and Narita International Airport, at its center. The western part of the Hitachi Plateau is the largest producer of Chinese cabbage in Japan, as well as many other vegetables, and industrial areas and suburban residential areas have also increased. The central area is Tsukuba Science City, and industrial areas and residential cities have developed along the JR Joban Line, while the eastern part is mainly rural, producing sweet potatoes, peanuts, and suburban vegetables, and a coastal industrial area has been established at the southern end of the Kashima Plateau. With Suigo Tsukuba Quasi-National Park at its center, the plateau offers great potential for regional development, including urbanization and industrialization.

[Akitoshi Sakurai]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

関東地方の東部にあり、利根川(とねがわ)下流低地を挟んで茨城県と千葉県にまたがる平地林の多い台地。茨城県側の常陸台地(ひたちだいち)と千葉県側の下総台地(しもうさだいち)からなる。関東構造盆地運動の影響を受けて、関東平野の中心にあたる茨城県古河(こが)市付近でもっとも低く約15メートル、周辺に向かって高度を増し、茨城県の筑西(ちくせい)市や鹿嶋(かしま)市で40メートル、千葉県の香取(かとり)市付近で40メートル、同山武(さんむ)市付近で50メートルに達する。地質は砂礫(されき)や粘土をもつ成田(なりた)層が主で、その上に関東ローム層がのっており、常陸台地では武蔵野(むさしの)面、下総台地では下末吉(しもすえよし)面にあたる台地面が広い。常陸台地は多くの河川でさらに那珂(なか)、鹿島、茨城、筑波(つくば)、稲敷(いなしき)、結城(ゆうき)、猿島(さしま)などの各台地に分かれる。下総台地は近世には馬の放牧地とされ、いまでは全国一のラッカセイの産地となり、近郊野菜の産も多い。また成田山新勝寺(しんしょうじ)と成田国際空港をもつ成田市を中心に、東京の近郊住宅地化が進んでいる。常陸台地の西部は、全国一のハクサイの産のほか多くの野菜を産し、工業地と近郊住宅地も増加した。中部は筑波研究学園都市、JR常磐(じょうばん)線沿いは工業地と住宅都市が開けたが、東部は農村が主で、サツマイモ、ラッカセイ、遠郊野菜の産地で、鹿島台地南端に臨海工業地域ができている。水郷(すいごう)筑波国定公園が中心にあり、都市化、工業化など地域開発の余地が大きい台地である。

［櫻井明俊］

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例