Tokoro-chashi Sites: Excavation Photographs Digital Archives

2 Excavations at the Okhotsk Locality (from 1998 to 2005)

(1) Overview of the locality and investigations

The Tokoro-chashi site Okhotsk Locality is an area consisting of pit houses of the Okhotsk culture located southwest of the chashi ruin, and north of the Tokoro-chashi sites. In this area, nine large pits were found in a survey carried out in the 1960s, and were considered as a settlement of the Okhotsk culture; however, no details were known until the start of a survey in 1998.

From 1998 to 2005, excavations of the pit houses at the Okhotsk Locality were carried out by the Department of Archaeology and the Tokoro Research Laboratory, Graduate School of Humanities and Sociology at the University of Tokyo, and Kitami City (former Tokoro Town) Board of Education, and the excavations of four pit houses (Pit Houses 7 through 10) were executed. These four pit houses were burned down when they were abandoned. A large number of artifacts were unearthed, including pottery, lithic, bone/antler, wood and metal artifacts, animal bones, together with carbonized pieces of wood. These artifacts revealed that all four pit houses belonged to the latter stage of the Okhotsk culture (the period of Haritsuke-mon series pottery; 8th to 9th century AD) (1).

Among the extensive results of archaeological investigations, artifacts from Pit House 7 are especially of note. Bone Mound a located in the innermost area of Pit House 7a yielded cranial bones of 110 brown bears. This is the largest number found in surveys conducted in Hokkaido, and therefore considerable attention was paid as to the reason it was constructed. Carbonized wooden artifacts from Pit House 7, such as containers and ornaments, are considered valuable artifacts because of the scarcity of similar examples.

All of the pit houses were reconstructed in an area, and burnt down when they were abandoned. These are common characteristics of all four pit houses, and are notable points when considering the structure and characteristics of the settlement, as well as the nature of ritual activities.

In addition to the pit houses mentioned above, the following features of Okhotsk culture have been found at the Tokoro-chashi Sites. Pit Houses 1 and 2 in their entirety were excavated in 1960 and 1963. In addition, parts of dwellings were found by general surveys at seven other pit houses (Pit Houses 3 through 6, and 11 through 13). There are at least 16 pit houses at the Tokoro-chashi Sites in total, including three unexcavated pits, which had been confirmed previously. Two burial pits, an outdoor bone mound, and animal bone concentrations have also been surveyed. Those archaeological features are considered to belong to the Late Okhotsk culture.

Based on the above scale and archaeological context of the sites, as well as the quantity and quality of excavated artifacts, the settlements at the sites are considered to be representative of Okhotsk culture.

In the following paragraphs, details of Pit Houses 7 through 10 are discussed, including form, size, reconstructing processes, and interior design.

(2) Pit House 7

Pit House 7 was rebuilt once.

It consists of two pit houses, Pit House 7a and 7b, with the outer older pit house being Pit House 7a, which has a hexagonal shape with the long axis measuring 12 m. In Pit House 7a, U-shaped Clay Floor a, Bone Mound a in the innermost area, and Hearth a lined with stone were found. For its part, Pit House 7b was rebuilt inside of Pit House 7a by utilizing the former used floor. The living space was reduced by building walls inside the older walls. Pit House 7b has a hexagonal shape with the long axis measuring 8.5 m. In Pit House 7b, Floor b, consisting of “=”-shaped Clay Floor b, Bone Mound b in the innermost area, and Hearth b lined with wood have been found. In addition, it can be ascertained that during the period of Pit House 7b, remodeling was performed, such as a downsizing of the innermost wall.

The floor level of Pit House 7b is same to that of Pit House 7a, and no vertical shift was found. Both of them were burnt down when they were abandoned.

(3) Pit House 8

The period of Pit House 8 can be divided into two phases. Here, traces of a dwelling suspected to belong to an earlier phase were found from directly below the floor that had been first discovered during excavation; however, no signs of reconstruction or indoor facilities of an earlier stage were clearly observed. Accordingly, Pit House 8 of an earlier phase has been expressed as Pit House 8 (Early Stage), and that in the newer stage as Pit House 8, thereby distinguishing it from the stage classification for other pit houses.

Pit House 8 has a pentagonal form with the long axis measuring 11.2 m, and has a U-shaped floor made of clay and boards, a hearth lined with stone and wood, and two bone mounds, one at the innermost area and the other at the opening area. Traces of Pit House 8 (Early Stage) include a former used floor distributed around the U-shaped floor of Pit House 8, former used ditches found from the lower position for those of Pit House 8, a concentration of gravel and pits below the floor of Pit House 8, although the details of the floor, hearth, bone mounds and others are not known.

While Pit House 8 was burnt down, it could not be determined whether Pit House 8 (Early Stage) was burnt down when it was abandonment.

(4) Pit House 9

Pit House 9 was rebuilt twice. Each time, traces of reconstruction by scaling down can be observed.

First, Pit House 9a, the largest, was built. Pit House 9a has a hexagonal form with the long axis measuring 11.9 m. In addition to Bone Mound a at the innermost area, Hearth a and b lined with wood, traces of a U-shaped floor and other items were found. Pit House 9b was constructed next by changing the direction of the long axis slightly clockwise, and reducing the area at the innermost side. Pit House 9b has a hexagonal form with the long axis measuring 10.5 m, in which Hearth a and b lined with wood, traces of a U-shaped floor, and other items were found. Pit House 9c was reconstructed by further changing the direction of the long axis clockwise while downsizing slightly toward the inside. Pit House 9c has a hexagonal form with the long axis measuring 10.4 m. Here, a U-shaped Floor c, Hearth c lined with stone, Bone Mound c at the innermost area and other items have been found.

The floor was reused throughout the period from 9a through 9c with the same floor level without any vertical shift. All of them were burnt down when they were abandoned.

(5) Pit House 10

Pit House 10 was rebuilt twice with complex shape modifications. The orientation of the entire pit house was moved significantly toward a front-rear direction along the long axis, while the living space was reduced sequentially.

First, Pit House 10a, the largest, was built. Although the exact shape is unknown because it was impossible to identify the wall at the opening side, it might have had a hexagonal form with the long axis measuring more than 11.2 m. Traces of U-shaped floor a at the innermost side, Bone Mound a at the innermost area, and a hearth—which was likely lined with stone—were found. Pit House 10b was reconstructed by reducing significantly the space at the innermost side of 10a, reducing the width slightly, and moving the entire living space significantly toward the opening side. Pit House 10b has a hexagonal form with the long axis measuring 9 m, and Hearth b lined with stone and parts of a U-shaped floor have been found. Pit House 10c was reconstructed by reducing the opening side of Pit House 10b significantly, reducing the width slightly, and moving the entire living space considerably toward the innermost area. Pit House 10c has a hexagonal form with the long axis measuring 7.9 m, here parts of a U-shaped floor, Hearth c lined with stone and Bone Mound c at the innermost area were found.

The same as Pit House 9, the floor was reused throughout the period from 10a to 10c with the same floor level. All of them were burnt down when they were abandoned.

1
The following report has been published regarding archaeological excavations of Pit Houses 7 through 10 at Tokoro-chashi site Okhotsk Locality from 1998 to 2005.