研究発表

景観は多義的な概念だが、今みるオセアニアの島嶼景観を人間の営為と自然の営力の絡み合いが生み出した歴史的産物として位置づけたい。その理解のためには、自然科学と人文科学を連接する歴史学の視点が役に立つ。オセアニア考古学では、過去20年ほどのあいだに地球科学や古生物学と協働するジオアーケオロジー調査が高い島を中心に進められ、人間と自然の関係史について多くの情報をもたらしてきた。近年、地球温暖化問題が関心を集めるなかで、オセアニア環礁についても、地球科学からの情報が急速に蓄積されてきている。地形学、堆積学、考古学、文化人類学の学際的チームがマーシャル諸島マジュロ環礁で2003年以来おこなってきた調査はその一例である。本発表では、その成果のなかからピット耕地の景観史について報告する。

Quoting some concepts of historical ecology and geo-archaeology such as 'portmanteau biota' and 'anthropogenic', oceanic archaeology has scrutinized historical interactions between two agencies, human and nature, producing the present island ecosystems and landscapes. In particular, the historical process of hill-slope erosion and alluvial formation resulting from agricultural activities has been illustrated in many studies on high islands, from which a concept of 'transported landscape' has consequently stood out: the reiteration of similar process on newly colonized island. Landscape history of oceanic atolls, however, remains a matter of speculation. Low and flat atoll islets of foraminiferal sand and coral shingle lie on mid-Holocene reef flats having emerged out ca. 2000-1000 yr. BP. While their monotonous image appears to be inherited even in the latest scientific reports, topographical and vegetational variations are discernible, some of which have been invented by agricultural activities. In fact, the pit-agricultural complex is one of striking anthropogenic features seen only in wider and larger islets having adequate rainfalls. This paper will present a brief overview of archaeological excavations in three atolls, Majuro in Marshall, Funafuti in Tuvalu, and Pukapuka in Northern Cook, and then describe historical entanglements of atoll islanders with their land, followed by a discussion on the variety of historical processes leading to the homogeneous pit-agricultural landscape.

A number of Oceanic atolls are scattered in the trade wind zone. The atoll-islets of sand and gravel lying on reef flats are often no more than 2 or 3 meters in elevation. There is no running surface water either, and thus some atolls frequently suffer from droughts. The atoll environment appears to be extremely severe for any human settlement. In our 2003 excavation of pit-agricultural bank in Laura, the largest and widest islet of Majuro Atoll in Marshall Islands, however, we got evidence indicating the earliest colonization dated back to 2000 yr. BP. Our 2006 excavations in the same islet, that is the main theme of this paper, is going to add the information on the progradation of its lagoon shore and the expansion of human settlement since the early centuries AD; therefore on the historical entanglement or interaction between two agencies, nature and human, generating the present landscape of an atoll islet.