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Kiryu is located in the Ashio mountain range, nestled in the Hirosawa (Hachioji) foothills. To the southeast lies the great basin area known as the Kanto Plain. The flat areas around Kiryu were constructed by the force of the Watarase and Kiryu rivers, whose headwaters are in the Ashio mountain range. The Ashio mountain region is the oldest geologic stratum in Gunma Prefecture. It was formed between 300 and 200 million years ago by accumulation on the ocean floor.

Iwajuku is one of the oldest Later Paleolithic sites in Gunma Prefecture, dating back to the late Pleistocene Era. The Jomon Period is characterized by the appearance of pottery making and a more settled way of life, accompanied by higher level technological skills. This period began in the late Paleolithic and continued into the Neolithic Age which corresponds with the Holocene geologic era. The Jomon Period covers a period from about 10,000 to 2,300 years ago. Jomon Period humans hunted the wild animals living in the mountains and lowlands, caught the plentiful fish living in the streams and rivers, and gathered nuts and grains available from the trees and fields. Hunting and gathering was the typical lifestyle of the late Paleolithic - early Neolithic humans.

The Kiryu area, surrounded by hills and mountains, and through which both the Watarase and Kiryu rivers flow, provided ample food resources for humans during this age.

Iwajuku Site and Tadahiro Aizawa

Tadahiro Aizawa
In September 1946, Tadahiro Aizawa, a resident of Yokoyamacho in Kiryu, discovered some obsidian fragments buried in the Kanto loam stratum on a bluff along a road in Iwajuku, a district of Kasakake Village (now Midori City). This discovery provided the proof required to establish human habitation in Japan during the Paleolithic Era. The Kanto loam stratum, a reddish layer of soil, is the accumulation of volcanic matter spewed forth during violent eruptions of the period.

The Kanto loam stratum was deposited during the Pleistocene Era (Diluvial Epoch) on the Japanese archipelago. This was a period of violent volcanic activity, evidenced by the repeated eruptions of both nearby Mt. Akagi and Mt. Haruna. It was a common belief at the time that humans could not have inhabited the area during such a violent age. Aizawa carefully preserved the stone tool fragment he had discovered buried in a layer of soil from an age most archeologists believed to have been uninhabitable.

World War II had just ended, and, discharged from military service, Aizawa took yo residence in Kiryu. Archeology was his pastime, a field that had captivated him since his childhood. He was particularly interested in finding out out when humans first started to inhabit the area at the base of Mt. Akagi. The Jomon Period, the oldest known Japanese culture at the time, was typified by pottery decorated with cord impressions, and pointed clay jars known as Tado-style pottery.

Aizawa made a living by selling natto (fermented soy beans) and notions, but as time allowed, he immersed himself in the study of local archeology. Having found some extremely old stone tools, Aizawa continued to examine the bluff in Iwajuku, hoping to find further evidence of human habitation in the red soil layer that would support his discovery.

In July 1949, Aizawa discovered an Obsidian point. He now believed he had enough evidence and fathered together the artifacts excavated from the loam stratum and took them to show a young researcher in Tokyo by the name of Teruya Eizaka. There, Aizawa was introduced to the young Meiji University archeologist, Chosuke Serizawa, who became his greatest supporter in his lifelong study of local Paleolithic archeology. Serizawa showed the artifacts Aizawa had discovered to Professor Sosuke Sugihara of Meiji University, who was taken aback in surprise. Sugihara decided to undertake further investigation of the site immediately.

Excavation at Iwajuku took place on September 11 and 12, 1949. The team included Sosuke Sugihara, Chosuke Serizawa and Isamu Okamoto, all of Meiji University; Tadahiro Aizawa was accompanied by Yasuhiro Horikoshi and Masayoshi Kato, two students from Kiryu Technical High School. Their excavation yielded several oval-shaped stone tools and other stone fragments.

A report written by Serizawa, Aizawa and Sekiya, entitled "Paleolithic Tools from the Base of Mt. Akagi", (akagi-san fumoto no kyu-sekki) recounts the following regarding the excavation of Iwajuku: "We began excavating the loam stratum on the bluff side of the road. The morning's work, however, yielded nothing conspicuous. We did find, nevertheless, some bulbous stone and obsidian fragments. After lunch, we continued to dig enthusiastically. The number of stone tool artifacts continued to grow. Bulbous stone fragments were typical and we also found some large obsidian fragments as well. In addition, there were two stone fragments which appeared to have been retouched". Ten minutes before excavation was to stop, Professor Sugihara discovered a stone ax in the 4th stratum. Upon retrieving the ax, he exclaimed, "Banzai!"

Iwajuku 1 stone tools

The discovery was reported in the September 20 issue of the Kasakake Village newspaper, and, as a result, the Iwajuku Site became the object of national attention. Few experts, however, were willing to recognize that Aizawaユs stone tool discoveries represented the first page in Japanese prehistory, and the atmosphere among academic circles was unenthusiastic.

Thereafter, the Meiji University team and Tadahiro Aizawa excavated the Iwajuku site on three further occasions, ending in 1950.

Fifty centimeters below the topsoil of Iwajuku Site is a layer of humic soil. This stratum dates back to the Jomon Era. About one meter below this stratum there is a red layer from which many stone points were excavated. This stratum is now referred to as the Iwajuku III Stone Tool Culture. The upper portion of this layer is fairly soft soil, while the lower portion is sandy. This sandy substrate is referred to as the Iwajuku II Stone Tool Culture, characterized by pointed stone knives. Below this, there is an approximately forty centimeter stratum of dark brown clay in which stone axes of the Iwajuku I Stone Tool Culture predominate.

Aizawa continued independently studying the Paleolithic culture at the foot of Mt. Akagi. He investigated the Gongen Site, the Kiribara Site, the Mitsuya Site, and the Masugata Site, accumulating a wealth of information. In other areas of Japan, Paleolithic sites similar to those of Gunma Prefecture were discovered and excavated, and little by little, opposition to the idea of the presence of humans on the Japanese archipelago during the Late Paleolithic Era declined.

Obsidian tool

The study of soil stratigraphy has contributed significantly to the definition of chronological eras. The research of Professor Fusao Arai and others of Gunma University on pryoclastic materials from volcanic eruptions continues to be on interest.

According to recent studies, in all, over 3,000 Late Paleolithic Era sites have been discovered in Japan from Hokkaido to Okinawa. Of that number, 150 sites are located in Gunma Prefecture. The oldest site in the prefecture is Irinosawa Site in Niisato Village, believed to date back some 40,000 years. Other Late Paleolithic sites (25,000 to 20,000 years ago) include: Otake, Kotake A, Ushiroda, and Zenjo sites in Tsukiyono Town, Tone-gun; Iwajuku III and IV sites include: Suwanishi, Naka'aze (lower stratum), Bungo Hatsusaki and Bogaito in Akagi Village, Seta-gun; and excavations in the lower stratum of Wada in Kasakake-cho, Midori City, the Furushiro site in Annaka City, and the Kitayama site in Fujioka City.

Sites dating between 20,000 and 15,000 years old have been excavated at the lower stratum of Minegishi in Niisatocho, Kiryu City and Mitate-Tamei in Akagi Village, which represent the Iwajuku II culture.

Sites ranging between 15,000 and 12,000 years old have been excavated in Kashiranashi, Maebashi City, Wada upper stratum in Kasakake-cho, Midori City, Kitayama in Fujioka City and the Minegishi upper stratum in Niisatocho, Kiryu City.

Sites dating from the final stage of the Late Paleolithic Era (12,000 to 10,000 years ago) have been found in Bogaito, Kita Tachibana Village in the Iwajuku ! culture stratum and the Kita Mitsugi site in Maebashi City.

Life Style Of Late Paleolithic Humans
Japan entered a glacial age from 2 million years ago to about 10,000 years ago. This long expanse of time was characterized by an extremely cold climate. The glacial age is divided into 5 glacial periods, between each of which there were warming periods. The most recent Wurm glacial period took place around 30,000 years ago, during which time the climate became relatively mild. Following that, the climate once again grew extremely cold and this condition persisted until some 20,000 years ago.

Pollen analysis is very useful in the study of prehistoric climatology. Fossilized pollen found in paleolithic strata has been analyzed. The results have allowed researchers to define the kinds of plants which were extant during any one period. Excavations of the Paleolithic strata in Soja-machi, Maebashi and Nikkawa in Niisatocho, Kiryu have revealed that the climate approximately 20,000 years ago in the lowland part of Gunma was similar to that of present day Oze March, the town of Kusatsu at the base of Mt. Shirane, or the caves on Mt. Akagi, all of which are considerably higher in elevation.

Naumann elephant

Given this kind of cold climate, we van begin to imagine the environment and life style of those who were living at that time. Perhaps the most well-known animals of the Late Paleolithic Era were the Naumann elephants, a slightly smaller version of the wooly mammoth found in Hokkaido, and bighorn deer. Bones of the naumann elephant have been found in a lime grotto in the Umeda 5 chome district of Kiryu, the Tomizawa district of Ota, the Osasa district of Tsumagoi Village, Azuma-gun, and the Fujiyama district of Kawaba Village, tone-gun. The bones of the bighorn deer were discovered in the Kamikuroiwa district of Tomoioka City after a landslide occurred there.

In the neighboring prefecture, Tochigi, the bones of the Asiatic black bear, raccoon dog, Japanese serow, Japanese macaque, and other animals were excavated in Kuzu Town, proving that they existed during the Late Paleolithic Era. It is believed that Paleolithic people probably gathered the buds of the japanese angelica tree, aralia plants, flowering ferns, hosta, mountain burdock, lily bulbs, yams, wild grapes, walnuts, and other edible plants for subsistence. It is also likely that these people chose to dwell in the forests on the hills, providing them with both protection and a good view of the surrounding area. To date, however, no Late Paleolithic dwellings have been discovered. It is unlikely that Paleolithic groups were able to construct solid dwelling such as those built by Jomon period groups. Most likely, they dug shallow, rounded encampments from which they engaged in hunting and gathering activities, moving regularly from place to place.

Bighorn deer

Although some 150 Late Paleolithic sites have been excavated in Gunma Prefecture, none of them provide evidence of Paleolithic dwellings. The Paleolithic pits excavated at Bogaito Site in Kita Tachibana Village, Seta-gun and the three varieties of stone tools discovered at the Kitayama site in Fujioka City give some indication of the life style during this age. Paleolithic research is currently ongoing in Gunma Prefecture.

Late Paleolithic Sites in the Kiryu Area
To date, no Late Paleolithic sites have been discovered within Kiryu City itself. An investigation of all the prehistoric sites in the city revealed that the oldest are Incipient Jomon Era sites. These are: the Fudoana site in Umedacho 5 chome, the Izuta and Fumonji sites in Hishi-machi 4 chome, the Ryudaiji and Sumiyoshi sites in Hishimachi 2 chome, the Yamanokoshi site in Hishimachi 3 chome, the Shinmeiyama site in Hirosawa 3 chome, and the Kanazuka site in Tsutsumicho 2 chome. It is believed, therefore, based on the multitude of Incipient Jomon Era sites, that Late Paleolithic sites may be found in Kiryu as well.

According to the research writings of Mr. Yoshi Sonoda in "kiryu shi hishi kyodo shi" (A Local History of Hishi, Kiryu City), the stone tools found at the Izuta, Sumiyoshi and Ryudaiji sites could possibly be Late Paleolithic artifacts. A scraper and other stone tools excavated from the lower loam stratum at Izuta in Hishimachi 4 chome, along with the stone tool implements found at Ryudaiji and in the sandy asphalt-colored stratum directly below the loam stratum at the Sumiyoshi site (points, blades, etc.) are Late Paleolithic-like implements, according to Sonoda.

From a geographic point of view as well, Kiryu would seem to be a likely site for Paleolithic habitation. Currently, research is underway to investigate this point.

Fudoana Site
There is a lime grotto in the mountainous Umeda 5 chome district, Takatate area (elev. 540 meters). The Kiryu River flows nearby with the grotto located about 40 meters above Takatake Dale. The entrance is about 15 meters wide and 2 meters high. It is a small grotto, about 3 meters deep. The archeologist, Takaichi Shuto, suspected that this lime grotto might prove to be a prehistoric site and undertook excavation there in January 1962. He discovered the bones of many animals along with Incipient Jomon Era pottery sherds. Following this, In October 1974, a teacher from Kiryu High School, Shigeo Miyazaki, also excavated the extinct plants and animals there along with the cave stratigraphy. His research uncovered Incipient Jomon Era stone tools and stone tool fragments and many bones of various animals which may have been eaten there by early Jomon people. The animal bones included bear, giant flying squirrel, Japanese boar, Japanese river rat, fox, marten, otter, Japanese wolf, and the first lynx ever to be discovered in the north Kanto region. The lynx weighed somewhere between 13 and 18 kg, had keen sight and hearing, and was very agile. The lynx possesses the power to kill deer three times its own weight. The fact that Incipient Jomon dwellers were sufficiently skilled to hunt and eat animals such as the lynx is quite amazing.

The bones of some 108 animals were discovered in the grotto, however, some of them could not be identified. Subsequent research and analysis proved that some of the bones were from the Naumann elephant. The Naumann elephant was a species which lived during the Paleolithic Era and became extinct during the Jomon Era. As yet, no Paleolithic stone tools have been excavated from the grotto, however, it may be conjectured that Paleolithic Era man hunted animals nearby and from time to time took up residence in the cave.

Paleolithic Era hunters - from the Gunma Prefecture Museum of History

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