Major excavations have been conducted at the Motodaka Yumi no Ki Iseki (本高弓ノ木遺跡) in Tottori city, Tottori prefecture, from May 2009, attending construction work on Japan National Route 9 (一般国道９号). Previous findings include Jōmon-period kubomiishi (凹石; pitted stones or cupstones), an Early-Kofun (circa 4th century) pond, water channel, and related wooden structure, and a Late-Yayoi (circa 2nd century) mound with paving stones (貼石), thought to be a mounded burial (墳丘墓).
A Jōmon-period kubomiishi (not related to the Motodaka Yumi no Ki Iseki; image source)
The most recent excavation (December 2010) was conducted at a yet deeper soil layer, revealing (1) an Early Yayoi store of lumber in a timber pond, and (2) the oldest Yayoi pottery for the Inaba (因幡) region,and (3) what looks to be a pre-Middle Yayoi dugout canoe.
Before discussing these most recent of finds in detail, let us look at a (selective) rundown of the site’s major findings:
*YBP = Years before present
*ZPKEF = Zenpoukouenfun (keyhole-shaped tomb)
| Period (YBP) | Main Site(s) / Artifact(s) | Notes |
| Nara to Heian periods (8th-12th centuries) | Loose, undefined paddy grid | Pre-Inaba-region implementation of jōrisei |
| Early Kofun Period (1,700-1,600 YBP) | Wooden structure(s), pond, water channel
One of the oldest sandbag piles |
Motodaka Kofun No. 14 (Oldest ZPKEF in San’in region)
Nascent Kofun water utilization and land development |
| Late Yayoi Period (2,000-1,700 YBP) | Mound with paving stones | Possibly a low-land tomb with four projecting corners (四隅突出型墳丘墓) |
| Middle Yayoi Period (2,200-2,000 YBP) | Water channel and residential area | Facilitated water use (irrigation?) and land development |
| Early Yayoi Period (2,500-2,20 YBP) | Water channel storing large amount of felled trees
Oldest Inaba-region Yayoi pottery |
Early Yayoi timber usage
Jomon to Yayoi transition, as seen in Inaba region |
(source)
Of particular interest is the find of loose, undefined rice paddy grids belonging to the Nara and Heian periods (8th-12th centuries). The national reorganization of agricultural land (jōrisei 条里制), implemented in the late 7th century required paddy fields to be rearranged into a systematic grid. That the paddy grid at the Motodaka Yumi no Ki Iseki was undefined and adapted to the local terrain suggests that the official agricultural reorganization (条里地割) first enacted in the late 7th century had not yet been implemented in the area now known as Tottori city. In addition, cow hoof prints found in the paddy fields (September 2010) dating to circa 1,400 YBP, judging from Asuka-period pottery unearthed nearby, bolster our understanding that agricultural work was conducted using cows as beasts of burden during this period. Judging from the even tracks up and down the paddy fields, the cows are believed to have been used for agricultural purposes. One possible use is the softening and preparation of ground before planting (shirokaki 代かき). Furthermore, the footprints of humans and cows dating to the Middle to Late Kofun period (400-600 AD) have also been found, as well as the sharply cloven hoof prints characteristic of deer.
Traveling backwards several hundred years, Motodaka Yumi no Ki Iseki has become a valuable resource in understanding the nature of Kofun-period public works projects. A 4th century (Early Kofun) ditch and pond, in addition to a dirt mound and wooden structure, were found accompanied by contemporaneous pottery in 2009. The mounded dirt and wooden structure (which was supported by pillars) are believed to have been implemented to control the flow of water. Of interest here is the method of piling dirt, which involved spreading down layers of sugi (Cryptomeria japonica) bark and matting (perhaps of rush).
(image source)
Stacked around the wooden structure are bags of earth (donō 土嚢) that have been remarkably preserved. The white band across the middle of the sandbag in the picture is a string, which has been preserved to such an extent that researchers are able to understand the type of knot used to tie the bag together.
It was announced in 2009 that an iron-bladed hand tool for plucking the heads of rice and other grains (鉄刃付き穂摘具) had been uncovered at the site in almost perfect condition – a domestic first. Dating to the Middle Kofun period, its condition is remarkable for a farming implement some 1,600 years old. The wooden base is made of Quercus acuta (コナラ属アカガシ亜属), and the iron blade is inserted into a groove made along the bottom. This being the first time an almost complete tool of this variety has been found, it is an indispensable clue to understanding the implement’s design. The photos provided below allow a glimpse into its practical use.
The iron blade can be seen along the bottom of the wooden block (image source).
A reproduction showing its practical use (image source)
In addition to this remarkable specimen, another cutting tool of a slightly different shape was found dating from the Early Kofun period (circa 300 AD), but only a section of its iron blade remains, highlighting how truly amazing the intact, Middle-Kofun find is. Not only is this the first time an almost complete specimen has been unearthed with the iron blade still fully inserted into the implement’s groove, this is also the first time two such implements with full/partial iron blades still inserted have been uncovered from the same archaeological site.
Moving to the results of the most recent investigation, an unprecedented store of felled trees was found in an Early-Yayoi water channel (timber pond), which measures approximately 20 meters in diameter and over one meter in depth (although, as the investigation is ongoing, a deeper location may yet be found), and was located on the village periphery. A residential area is believed to have been located nearby.
A Kofun-period channel nearby (image source)
Most of the logs measure 20-30 centimeters in diameter and 1-3 meters in length, but one giant among them is 11 meters long and 80-100 centimeters in diameter. As of December 25, 2010, around 200 logs have been uncovered, and researchers suggest that more may appear as investigations proceed.
(image source)
Three trees of especially large girth were examined and identified to be of two varieties: One was keyaki (Zelkova serrata) and the remaining two were mukuroji (Sapindaceae). Identification of the remaining trees is scheduled for after the immediate excavation. Keyaki is a deciduous tree that keeps well, a characteristic the Yayoi people must have known, as they tended to use it for containers. Also a deciduous tree, mukuroji is lightweight and pliable; the Yayoi people used it to make piles and stakes.
Artifacts made of keyaki, which is often formed into containers or used as a building material, have appeared at numerous other Yayoi sites. A Yayoi-period keyaki takatsuki (高杯; pedestaled bowl) was uncovered at the Aoya Kamijichi Iseki (青谷上寺地遺跡) in Aoya-chō (青谷町), Tottori city. Keyaki with especially large diameter are believed to have been bereft of their core shaft, which was then cut into multiple pieces, each of which was then molded into bowls or containers. The Yayoi people were therefore quite judicious in choosing which trees to use based on their intended use.
The lack of bark and leaves in the water channel (and the lack of logs with bark and leaves attached) suggests to archaeologists that the timber was prepared – branches stripped and bark peeled – in the woods immediately after felling. In addition, this condition of the lumber affirms that the trees were treated and gathered by human hands, and had not fallen naturally (自然の倒木). The trees also lack roots and bear what researchers posit are axe marks, which further solidifies the identification of the lumber as felled by human hands and purposefully stored alongside a residential village. Early-Yayoi pottery found in the same layer places active utilization of the water channel to circa 2,500-2,200 years ago.
Storing lumber in water, a method used even today, keeps insects from burrowing within, prevents rotting, and helps retain the wood’s color. Yayoi-period demand for lumber (for building purposes), judging from the volume of this site, was quite great, and their experience with raw materials must have been beneficial in teaching them storage techniques, as timber stored in a dry state may crack and warp, eventually becoming useless.
While a Yayoi-period collection of lumber has been previously unearthed at Nishi no Tsuji Iseki (西ノ辻遺跡) in Higashi Ōsaka city, Ōsaka prefecture, it dates to the early Late Yayoi (approximately 2,000 YBP), making the Motodaka Yumi no Iseki find the oldest in the country.
The second major recent find was of early Early Yayoi pottery, the first for the Inaba region (因幡地域), or eastern Tottori prefecture, which was uncovered from the timber pond; it was unearthed alongside a deep bowl (深い鉢) from the Latest Jōmon (縄文晩期末). All that remains of the Early Yayoi piece is a sherd from the rim of a jar-shaped pottery (壺形土器) specimen. Judging from the short rim and its slight outward curvature, it belongs to the earliest Yayoi pottery, hitherto unknown in the Inaba area (although such Early Yayoi pottery has been uncovered at central and western Tottori sites).
The third major find was what looks to be a dugout canoe (marukibune 丸木舟). While the whole length is apparently unknown, as the log continues past the boundaries of the current excavation area, its tapered end and hollowed-out interior suggest quite strongly that it is, indeed, a canoe. The absence of nearby pottery makes it a difficult find to date, but judging from its position below a Middle-Yayoi layer (approximately 2,000 YBP), it is believed to at least predate the turn of the millennium. While the base of the canoe measures 5-6 centimeters thick, the sides are only 2 centimeters, giving researchers a glimpse into the design of Yayoi canoes.
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For photos and detailed information, see this site. An older press release is available here (original source), and contains additional details on previous finds.
See the 現地公開資料 HERE.
For more pictures, see this PDF (original source).
See this article concerning the iron-bladed farming implements.
本高弓ノ木遺跡：丸太１３０本以上 弥生前期の水路遺構から出土－－鳥取 ／鳥取
毎日新聞 12月22日(水)15時52分配信 [2010]
鳥取市本高の本高弓ノ木遺跡で、弥生時代前期（約２５００年前）の水路の遺構から１３０本以上の丸太材が見つかったと県教育文化財団が２１日、発表した。丸太を蓄えた遺構としては弥生時代最古級で、本数の多さは例がないという。
出土した丸太材は、直径２０～３０センチ、長さ１～３メートルほどのものが多く、最大で直径約１メートル、長さ約１１メートル。人為的に枝が切り落とされ、樹皮も剥がされていた。一緒に出土した土器から時代を特定した。集落の外れにある幅２０メートルの水路に蓄えられていたらしい。
弥生時代の木製品に詳しい鳥取大地域学部の中原計准教授は「丸太材のままこれだけ大量に見つかったのは弥生時代では初めて。当時の木材加工の工程を知る上で非常に貴重な資料」と話している。
また、これまで県東部で見つかっていない弥生時代前期の土器片も出土した。つぼの口の形や反り具合から年代が分かった。縄文時代晩期の土器片と一緒に見つかったことから、縄文から弥生への土器の移行を知る手がかりになるという。
現地説明会は２５日午後３時から。問い合わせは同財団（０８５７・５１・７５５３）へ。【田中将隆】１２月２２日朝刊
http://headlines.yahoo.co.jp/hl?a=20101222-00000269-mailo-l31
AR2010/12/27
弥生前期の貯木場跡出土、丸太２００本 本高弓ノ木遺跡
2010年12月25日
因幡地域で最古とみられる弥生土器（左）と縄文時代末期の深鉢の破片
直径８０センチ以上のケヤキ（中央）など約２００本の丸太材が出土した貯木場跡＝鳥取市本高の本高弓ノ木遺跡
鳥取市本高の本高弓ノ木遺跡から弥生時代前期（約２５００～２２００年前）とみられる貯木場跡が見つかり、約２００本の丸太が姿を現した。弥生時代の貯木場跡はこれまで大阪府東大阪市の西ノ辻遺跡（約２千年前）が最古とされていた。調査している県教育文化財団は「当時の木材加工の工程を知るうえで貴重な資料」と言う。丸太群は調査地にある延長約７０メートル、幅約２０メートルの水路跡を約１メートル掘り下げた砂層から出土した。直径２０センチ前後が最も多く、最大は直径８０センチ、長さ１１メートルのケヤキ材だった。いずれも枝打ちや樹皮をはぐ加工が施されていた。根もなかった。財団の浜田竜彦副主幹は「近くで伐採した丸太を水中で貯木していたと考えられる」と話している。
同じ地層から因幡地域で未確認だった弥生前期の特徴を持つつぼの破片（縦横各１５センチ）が出土し、年代推定の手がかりとなった。ほかに石おのの柄に加工中とみられる木の棒（長さ１．１メートル、直径４センチ）も見つかった。
弥生時代の木製品に詳しい鳥取大学地域学部の中原計准教授は「丸太ばかりの集積跡は非常に珍しい。当時は器や柱材など何にどの樹種を使うか決まっており、近くの集落が自家消費するためにためていたのだろう」と話す。
現地は山陰道の鳥取西道路建設に伴って２００９年度から調査が始まり、これまでに弥生後期の四隅突出型墳丘墓に似た盛り土が出土した。丸太は輪切りにして複数のサンプルを取った後、盛り土で覆う。
２５日午後３時から一般公開がある。小雨決行。悪天時は２７日午前１０時に順延される。問い合わせは財団（０８５７・５１・７５５３）へ。（中田和宏）
http://mytown.asahi.com/areanews/tottori/OSK201012240105.html
AR2011/01/29
