工藤 雄一郎

魚住泊は，天平年間に僧行基が播磨・摂津国に置いた五泊の一つである。その場所については，現魚住港説，江井ヶ島港説があるが，確かな証拠に乏しかった。このたび，1986年に江井ヶ島港に接する赤根川の河口から見つかった木椋の一部とみられるマツ材の¹⁴Ｃ年代を測定した。較正年代から伐採年代は10世紀と推定された。この年代は，914年（延喜14年）に三善清行が朝廷に魚住泊の修復を願い出た年代に対応する。魚住泊は，赤根川の河口に木材で基礎を造り石と土を用いて突堤を築き，船溜りをつくったのが起源で，そこが現在の江井ヶ島港に継承されているのであろう。Uozumi-no-Tomari is one of the five ports opened in Harima and Settsu Provinces in the Tenpyo¯ period (729‒749) by a monk named Gyo¯ki. It was believed to have been located in the present port of Uozumi or Eigashima though there was not ample evidence. In this study, radiocarbon dating was performed on the samples taken from the timbers excavated in 1986 at the mouth of the Akane River next to Eigashima Port. The calibrated radiocarbon dates indicated that they had been felled in the 10th century, which coincides with Engi 14 (914), when Miyoshi Kiyoyuki applied to the Imperial Court for the restoration of Uozumi-no-Tomari Port. It is considered that the origin of the port was a quay with wooden foundations and stone and soil banks at the mouth of the Akane River and that it has become the present port of Eigashima.

「縄文時代の始まり」あるいは「最古段階の土器」の研究は1950年代以降，¹⁴C年代測定と古環境研究の進展と常に密接に絡みながら進んできた。そこで本論では，これらが更新世/完新世（洪積世/沖積世），氷期/後氷期の境界，あるいは晩氷期と，どのように対比されてきたのかに注目して，戦前から現在までの研究の流れを整理した。縄文時代の始まりは沖積世の海進のピーク以後というのが戦前の一般的な地質時代観であったが，それが大きく変わる画期となったのが撚糸文土器の発見と夏島貝塚の¹⁴C年代測定であった。9,000年前を遡る土器と後氷期の開始が結び付けられ，考古学界には「後氷期適応論」が普及した。1963・1966年に公表された福井洞窟や上黒岩岩陰の¹⁴C年代は12,000年代まで遡り，氷期/後氷期の境界として認識されていた1万年前を超え，最古の土器を縄文時代から切り離す時代区分が提案されるきっかけとなるとともに，土器の出現と晩氷期との対比も始まった。1990年代になると，グリーンランド氷床コアなどの高精度の古環境研究が公開され，較正曲線IntCal93によって土器の出現が15,000年前まで遡る可能性が示されたが，決定的な画期となったのは1999年に公表された大平山元Ⅰ遺跡の較正年代であった。土器の出現が16,000年代まで遡るとともに，晩氷期を突き抜けて最終氷期の寒冷な環境下で土器が使用され始めたことが判明し，「土器出現の歴史的意義」と時代区分の画期としての土器の出現についても再検討が行われはじめた。2000年「佐倉宣言」以降は較正年代の理解とその使用が普及し縄文時代の始まりの年代と古環境との詳細な対比が行われるようになり，時代区分の再検討も進みつつある。Since the 1950s, research into the "beginning of the Jomon Period" or the "absolute date of the earliest pottery" has consistently progressed in close relation to advances in radiocarbon dating and paleo-environmental research. Therefore, in this paper I have arranged the flow of research from the late 19th century to the present, focusing attention on the ways in which these have been compared with the boundaries of the Pleistocene/Holocene (Diluvium/Alluvium) and the boundary of the Last Glacial /Post-Glacial or the Late Glacial. In the 1930s and 1940s, the general view of the geological age in the archaeologist were that the Jomon Period started after the peak of coastline transgression in the mid-Holocene. However, this view changed radically with the excavation of cords-marked stick pattern (Yoriitomon) pottery and radiocarbon dating of the Natsushima shell mound published in 1959. Radiocarbon ages of the Natsushima shell mound dated about 9,000 years ago revealed that the appearance of pottery coincided with the start of the Post-Glacial period. It triggered that "Post-Glacial period adaptation theory" spread throughout the archaeologist. In 1966, however, it was reported that the linear–relief (Ryusenmon) pottery at the Fukui Cave and Kamikuroiwa site had a radiocarbon age going back as far around 12,000 years, exceeding the boundary of the Glacial /Post-Glacial, which was recognized as being around 10,000 years ago. These results led to the proposal of new periodization which removed the oldest pottery from the Jomon Period. In relation to this, a few researchers have started comparisons between the appearance of pottery and the Late Glacial in 1970s. By the 1990s, high-precision paleo-environmental research of the Greenland ice cores, etc. had been publicized, and the calibration curve IntCal93 indicated that the appearance of pottery might possibly go back as far as 15,000 years ago. Final major breakthrough was announced in 1999, when the radiocarbon dates of charred adhesion on potteries at the Odai Yamamoto I site were measured and calibrated by IntCal98. As well as indicating that pottery first appeared as far back as around 16,000 years ago, it was established that pottery was first used in the cold environment of the Last Glacial, cutting into the Late Glacial. These new results for the earliest potteries led to the reconsideration of the "historical significance of the appearance of pottery" and its groundbreaking periodization. Understanding of calibration dates and the use thereof has spread since the "Sakura Declaration" of 2000, making it possible to conduct detailed comparisons of the beginning of the Jomon Period and the environmental setting, while advances also continue to be made with reconsideration of periodization.

第23回名古屋大学年代測定総合研究センターシンポジウム平成22(2010)年度報告