A campsite found in a buried river basin. The stone blade manufacturing technique of 30,000 years ago comes to light.

Remains of tool making
from approximately 30,000 years ago (in situ finds at the Nakahigashi Site, Location No. 2)
Numerous flakes and bits of detritus produced when obsidian was split were found in the area around an anvil stone (at center, circled).

How were stone tools made? (refitted material)
Eighteen flakes and bits of detritus were refitted. Traces of striking off stone tools are seen running repeatedly in vertical fashion, from which we can discern that people at the time were not making tools simply by splitting the raw material randomly, but rather with the intent to produce long blades. Length: 5.2 cm.

Sites spread alongside buried rivers
Closely examining the contour lines, there are faint depressions on the tableland. When surface surveys and excavations were conducted in the vicinity of these depressions, it was learned that former rivers are buried there. It has recently become clear that sites are spread alongside the courses of these rivers. The Sunagawa river as well, which at present has been converted into an urban sewer main, formerly appeared in times of heavy rain, but in dry seasons was a subterranean stream with no surface flow until the lower reaches of the river.
Adapted from Hakkutsu sareta Nihon rettō 2012 [Excavations in the Japanese Archipelago, 2012] (Bunkachō [Agency for Cultural Affairs], ed., Asahi Shimbun Publications, 2012).

Locations of the site (circle) and obsidian sources (triangles)
Adapted from Hakkutsu sareta Nihon rettō 2012 [Excavations in the Japanese Archipelago, 2012] (Bunkachō [Agency for Cultural Affairs], ed., Asahi Shimbun Publications, 2012).

Obsidian brought from the Izu peninsula, 120 km distant (refitted material)
Forty-seven flakes and bits of detritus were refitted. The raw stone is thought to have been around 13 cm long, 8 cm wide, and 6 cm thick. As there were no pieces that fit the central portion, it is believed the stone was worked to a certain degree at this location, then carried off somewhere else.

Principal artifacts, Nakahigashi Site
Adapted from Hakkutsu sareta Nihon rettō 2012 [Excavations in the Japanese Archipelago, 2012] (Bunkachō [Agency for Cultural Affairs], ed., Asahi Shimbun Publications, 2012).

Nakahigashi Site, Miyoshi Town, Saitama Prefecture

A site in an unlikely location

In the Paleolithic era, it was colder and drier than the present day. Because people lived in camps along rivers, or at places where water gushed out from under a cliff, hoping to catch animals drawn there, most of the sites lie along small streams of tablelands.

But from the Nakahigashi site, located on the northeastern part of the Musashino Terrace at a place with no river today, traces were found of the manufacture of many stone tools from materials such as obsidian.

The age of the site (from ca. 30,000 to ca. 19,000 years ago) places it in the Upper Paleolithic Era. Since 1992, as the result of analysis of contour lines, and geological surveys conducted in addition to archaeological investigations, it has become clear that a river formerly flowed in this area, which at present is level and has no river, and in the vicinity there are multiple sites from the same period. A new perspective has thus opened for future investigations of Paleolithic sites. (Echizenya Tadashi)

The Tachikawa loam layer which yielded stone tools

More than 3,300 items of stone tools and small stones have been recovered from both banks of the buried river at the Nakahigashi site. The stone tools are from approximately 30,000 (Tachikawa loam, Layer IX) to 19,000 (Layer III, upper portion) years ago, and come from every soil layer. In addition to knife-shaped stone tools of obsidian used in hunting, end- and side-scrapers for butchering game have been found, and now it is clear that over a long span of approximately 10,000 years, people repeatedly came to this spot, time and again making tools and hunting, butchering and cooking, while living a camp life.

Obsidian brought from afar

Of the 1,369 obsidian stone tools recovered from soil layers of about 30,000 years ago, roughly 87 percent were produced with obsidian from the Kashiwa pass, near the Mount Amagi volcano on the Izu peninsula, and others are also known from Hatajuku along the Sukumo river of Hakone, and the Wada pass in Nagano prefecture.

Among these are multiple examples of stone tools of material from the Kashiwa pass and Hatajuku which can be refitted into shapes close to the original stone. From these refitted materials, the technology of approximately 30,000 years ago for taking long flakes and using these to produce knife-shaped stone tools, is coming to light. (Ōkubo Jun)