@article{oai:soar-ir.repo.nii.ac.jp:00011899,
 author = {公文,  富士夫 and 井内,  美郎},
 journal = {地質学論集},
 month = {Nov},
 note = {All-Core boring 45.10m long from the bottom surface of Lake Nojiri was carried out 250m south of Biwajima Island. The upper half of the boring sample was obtained by a special piston core-sampler, while the lower half was taken by drilling without water. The upper two-thirds of the core sample is composed mostly of clayey silt or silty clay, and was named the NoJirikotei Clay Formation The lower one-third of the core sample, named the Biwajimaoki Peat Formation, consists mainly of peat. Both formations contain many tephra layers including four widespread tephras. The lowest part of the core, about 1m long, is composed of ill-sorted tuff with pumice and breccias, and forms the basement for the sediments. Major tephra layers in the core sample can be correlated with the key beds in the Nojiriko Excavation Site. The well-known and widespread Akahoya and Aira-Tn Tephras are found at 387cm and 1021 cm depths, respectively. The age of the Akahoya and Aira-Tn Tephras have been determined by many ¹⁴C datings. The volcanic breccia named "Breccla Zone" at a depth of 1621 cm has been dated of 36,000 Y. B. P using the mean of three ¹⁴C datings. Based on the above data sedimentation rates ｗere calculated to have been 0.60 mm/y above the Akahoya Tephra and 0.42 mm/y between the Akahoya and Aira-Tn Tephras. The sedimentation rate below the Aira-Tn Tephra was 0.62 mm/y The age of the key tephras can be calculated using the sedimentation rates. The Biwajimaoki Peat Formation ranges from about 100,000 to 53,000  Y.B.P., and the Nojirikotei Clay Formation ranges from 53,000 Y.B.P. to the present. Acoustic reflectors by Uniboom correspond to the major tephra layers. The first reflector coincides with the Otagirigawa Volcanic Ash (4,000 Y.B.P),the second with the Kibidang Ⅱ Volcanic Ash" (11,400 Y.B.P), the third with the "Nuka I Volcanic Ash" ＝ Aira-Tn (21,000 Y.B.P), the fourth with the   Jouichi-Pink Volcanic Ash" (27,000Y.B.P.), the fifth with the Akasuko Scoria" (30,000 Y.B.P.), the sixth with the "Doraikare Volcanic Ash" (35,000 Y.B.P.), the seventh with "Santensetto Tephra" (43,000 Y.B.P.) and the eighth with the "Nomi Scoria" (47,000 Y.B.P). The isopach maps based on the depth of specific acoustic reflectors indicate that the depositional center was located in the western part of the lake between 53,000 to 27,000 years ago. The center then moved eastward to its present location. The water level seems to have been rising gradually. The eastward movement of the depositional center and the rising Water level were controlled by the upheaval of the Nakamachi Hill west of Lake Nojiri., 野尻湖底において, 45.10mのオールコア･ボーリングを行った.上部の約34mは粘土質堆積物を主としており,野尻湖底粘土層と命名された.下部の約10mは泥炭(琵琶島沖泥炭層)であった.両層には4層の広域テフラを含む多数のテフラが挟まれていた.最下部には1 m以上の厚さの含角磯凝灰岩があった.堆積速度に基づいておもなテフラの年代を推定した.琵琶島沖泥炭層は約10万年前～5.3万年前まで,野尻湖粘土層は5.3万年前～現在までの連続的な堆積物であることも判明した.音波探査記録の反射面は,野尻湖西岸の発掘地で認められているテフラ鍵層に対応することが確認でき,その年代も明らかになった. 5.3万年前から2.7万年前までほ現野尻湖の中央より西側に堆積の中心があり,それ以後は,東側に堆積の中心が移動した.野尻湖における貯水の始まりと湖盆の東への移動と拡大は,野尻湖西側の仲町丘陵の隆起運動に支配されていたと考えられる., Article, 地質学論集 36: 167-178(1990)},
 title = {野尻湖の湖底ボーリング試料と音波反射層との対比},
 volume = {36},
 year = {1990}
}