抄録
Lake Nojiri is located in the northern part of Nagano Prefecture at lat. 36°49′N, long. 138°12′E. It is a unique site where a wealth of mammalian fossils and many Paleolithic artifacts have been unearthed from the lacustrine sediments.
The first Lake Nojiri Excavation was undertaken in 1962 on the shore of the lake to identify the stratigraphic horizon of the fossil molar tooth of Palaeoloxodon naumanni, which had been found there by a proprietor of the lakeside hotel. Thereafter, six excavations on the shore and three excavations on the hill site near the lake have been carried out until 1979.
These excavations have marked a highly significant step in establishing a satisfactory connection between geology and archeology in Japan on the basis of precise stratigraphic research works. It set out to reconstruct a standard history of Late Pleistocene men and its nature around them in Japan.
The voluminous report entitled “The Paleolithic Site and Paleoenvironment in and around Lake Nojiri” was published in the Memoirs of the Geological Society of Japan, No. 19 (1980). The present paper is a brief report of the Lake Nojiri Excavation Research work, focussing on a paleoenvironmental change of Late Pleistocene around Lake Nojiri.
Stratigraphic successions of lacustrine deposits at the lake shore as well as of aeolian deposits on the western hillside of the lake were established. The complete correlation between these two sedimentary sequences was done by the precise stratigraphic studies of the tephra intercalations therein. Fig. 5 summarizes the stratigraphic successions with the important data including absolute ages, Paleolithic artifacts, fossil faunas and floras, paleoclimate, volcanic activities and lake-water level. Several paleogeographic maps around Lake Nojiri during Late Pleistocene and thereafter are shown in Fig. 4.
14C age determinations suggest that the deposits in and around the lake are of Late Pleistocene in age, ranging from 10 to 50 thousand years B.P. The coldest period of Late Glacial Stage corresponds to the deposition of the Upper Nojiri-ko Member. This is suggested by an examination of fossil floras including pollen therein.
The upper part of the Lower Nojiri-ko Member to the upper part of the Middle Nojiri-ko Member possibly corresponds to the Aurignacian period of Europe, indicating a Late Paleolithic culture with a relic from the Neanderthaloid. Some part of the Upper Nojiri-ko Member and the Upper Nojiri Loam (Volcanic ash) Member are assignable to the Mesolithic period, and the Kashiwabara Black Ash Formation to the Johmon (Neolithic) period and later.
