Located in the north of Shuangdun Village, Huaishang District, Bengbu City, Anhui Province, the Bengbu Museum was discovered during the 1985 cultural relics census, and rescue archaeological excavations were carried out in 1986. In order to cooperate with the State Administration of Cultural Heritage "Sulu Yuwan Pre-Qin Archaeology Key Project", the Anhui Provincial Institute of Cultural Relics and Archaeology conducted two quarters of archaeological excavations in 1991 and 1992. A large number of pottery, stone tools and bone horn mussels have been excavated, as well as rich pottery carved symbols, which greatly enriched the academic community's understanding of the cultural appearance of the middle Neolithic period in the middle reaches of the Huai River, and the academic community proposed the naming of the Double Pier culture. In October 2014, the Secondary Archaeological Excavation Project of Shuangdun Site was launched, aiming to clarify the settlement structure of Shuangdun Site through the research method of settlement archaeology.
Figure 1 Aerial view of the excavation area of the Shuangdun site
We first conducted a comprehensive survey and preliminary exploration of the site, and the drilling showed that the Shuangdun site was surrounded by water on three sides, landed on one side, and the existing area of the core area of the site was about 10,000 square meters. Cultural accumulation is concentrated in the southwest and southeast directions of the site, and pottery pieces and snail shells are found in many areas. We selected the western part of the site for the Bufang excavation, and the excavation area is about 650 square meters. Under the excavation area (2) layer, a large area of pottery pieces and animal bone accumulation layers is exposed. (3) The layer is a reddish-brown soil accumulation, which is widely distributed throughout the excavation area, the soil is loose, and due to the inclusion of a large number of pottery pieces and animal bones, the surface cannot distinguish independent behavioral units. The earth color of the northeast and southwest changes slightly, so it is divided into two parts: (3)a and (3)b. (3) Part b pottery pieces and animal bones are relatively sparse, and the block diameter is relatively small. (3) Part a pottery pieces have a large diameter and dense distribution. The local area in the northeast is exposed to (4) layers, (4) layers are light gray-brown soil, loose soil, large animal bone density, mainly pig and deer mandibles and limb bones. The south-central part of the excavation area exposed a northwest-southeast trend of pottery pieces, snail shells and animal bone accumulations, including densely distributed snail shells and river mussels, which were identified as the largest number of Chinese round field snails, as well as spinnaker mussels, wedge mussels and lismus mussels, etc., with complex species.
Figure 2 Accumulation of pottery pieces at the site
Figure 3 Animal bones piled up on the third layer of the site
Exploration shows that the core area of the Shuangdun site is more than 10,000 square meters. The site is artificially built on loess mounds, surrounded by water on three sides and facing the land on one side. The northern, western and southern sides are gentle slopes, the eastern side is slightly steeper, and the northeast part is damaged by soil extraction, forming a steep cliff. The rammed earth platform is located under the (3) floor of the site and is divided into two layers. The upper plane is square, and there is a rectangular passage in the northwest and southeast parts. Rammed soil is reddish-brown soil with a tight structure and inconspicuous rammed layers. There are more yellow and gray soil particles, a small amount of charcoal chips, braised soil particles and sand soil particles. The rammed soil drilled is about 30-36 meters long (the perimeter is a gentle slope of about 3 meters wide). There is a passage in the northwest and southeast of the base, and the northwest channel is drilled from east to west to about 4 m long and about 3.5 m wide, and the west is disturbed or destroyed. The southeast passage is drilled to the north and south about 9 meters long and about 3.5 meters wide. The top of the platform is basically flat, 1.2-1.6 meters from the surface, the thickness of the foundation is about 0.5 meters, and the area is more than 900 square meters. The lower layer is basically rectangular and runs east-west. There are layers on the pedestal, and the upper parts may be screened or artificially trampled. The lower layer is relatively pure, and the rammed layer is not obvious. The rammed soil drilled is about 70-76 meters long and about 45-5 meters wide (the perimeter edge is about 3 meters of slope protection), and the top area of the platform foundation drilled is about 3000 square meters. The top of the platform is flat, 1.7-2.1 meters from the surface, and the total height of the foundation is about 1 meter. The characteristics of the surface of the platform need to be revealed by the next archaeological excavation, and whether the pile of the foundation is inhabited by humans or sacrifices still needs to be excavated.
Fig. 4 Pottery pieces and shell accumulation excavated from the fifth layer of the site
From 1991 to 1992, the remains of inclined accumulations of grooves were found in the southeast of the site, and a large number of pottery pieces and animal bone remains were found in the grooves, and similar accumulations were also found in archaeological excavations in the western part of the site from 2014 to 2015. At present, the pottery pieces and animal bone accumulation layers below the (3) layer are distributed around the rammed earth platform foundation, and the drilling found that the accumulation at the top of the platform foundation is quite pure. The terrain around the platform foundation was quite low-lying at that time, and the paving direction of the accumulation of pottery pieces and animal bones also came from the foundation.
Figure 5 Distribution of the base range of the Shuangdun site exploration in 2015
Archaeological exploration and excavation work in 2015 revealed that the terraces in the core area of the Shuangdun site are mainly artificially stacked, and the remains found so far are all around the foundation, with a base area of about 3,000 square meters, plus the surrounding pottery pieces, an area of only 10,000 square meters. The layout of the core area of the site has led us to reflect on the structure of the site, and the current core area of the site may not be a major human settlement, and it is likely that some kind of large-scale human swarm activity is related.
Excavation unit: Anhui Task Force, Institute of Archaeology, Chinese Academy of Social Sciences, Anhui Institute of Cultural Relics and Archaeology, Bengbu Museum
Team Leader: Liang Zhonghe
Executive Team Leader: Zhang Dong
Participant: Zhang Zhongyun (Anhui Institute of Cultural Relics and Archaeology)
Zhao Lanhui (Bengbu Museum)
Kong Lingli, Bi Daochuan, Fu Qunqi, Yang Jiejie, etc. (Technician of the Institute of Archaeology)
Author: Zhang Dong
Jointly planned by the Scientific Research Office of the Institute of Archaeology and the China Archaeological Network