What is a Shell Midden? Data Recovery Excavations of Thom's Creek and Deptford Shell Middens, 38BU2, Spring Island, South Carolina

Data recovery excavations were conducted at five shell midden loci of site 38BU2, Spring Island, Beaufort County, South Carolina. The excavations included: four by four m blocks in three Deptford phase middens; a four by four m block in a Thom's Creek midden; a six by six m block in a Deptford midden; and two exploratory one by one m units in other Deptford middens. The analyses included detailed zooarchaeological and ethnobotanical studies, an investigation of oyster source environment and seasonality, and a detailed perusal of the stylistic and technological variation between and within middens. In addition, the overall assemblage traits were compared within and between phases.
The results support an evolving model of prehistoric midden development which emphasizes that all shell middens were not formed by the same activities. It is clear that the Thom's Creek midden at 38BU2 was the locus of diverse domestic activities beyond basic shellfish gathering. It appears that the Thom's Creek midden accumulated during repeated, seasonal semi-permanent occupations.
In contrast, the Deptford phase middens all exhibit the following traits: very low frequency of vertebrate faunal remains; virtual lack of shell, bone, lithic, or sherd tools; low frequency of ceramic sherds/vessels; very minor contribution by non-oyster shellfish; and lack of ideotechnic items. These Deptford middens are consistent in form and content with other known Deptford/Wilmington middens in the Beaufort County area. It is suggested that they represent oystering stations where large numbers of oysters were processed by a few individuals for surplus storage or exchange.

本次资料收集性发掘在美国南卡罗来纳州博福特县斯普林岛38BU2遗址的5处贝丘（shell midden）发掘点开展。本次发掘布设的探方包括：3处德普福德期（Deptford phase）贝丘内的4×4米探方、1处汤姆溪（Thom's Creek）贝丘内的4×4米探方、1处德普福德期贝丘内的6×6米探方，以及其余德普福德期贝丘内的2组1×1米勘探探方。分析工作涵盖详细的动物考古学（zooarchaeological）与植物考古学（ethnobotanical）研究、牡蛎来源环境及季节性特征调查，同时对各贝丘内部及贝丘间的风格与技术变异展开细致梳理；此外还对不同阶段内部及阶段间的整体遗存组合特征进行了对比分析。
研究结果支持史前贝丘演化的动态模型，该模型强调并非所有贝丘均由同一类活动形成。显而易见，38BU2遗址的汤姆溪贝丘是开展基础贝类采集之外多种居家活动的场所，该贝丘应形成于反复进行的季节性半永久居留活动期间。
与之形成鲜明对比的是，德普福德期贝丘均呈现如下特征：脊椎动物遗存出现频率极低；几乎未见贝壳、骨器、石器（lithic）及陶片工具；陶片/陶容器的出现频率较低；非牡蛎类贝类的贡献占比极低；且缺乏意识形态类遗物（ideotechnic items）。此类德普福德期贝丘在形制与内涵上，与博福特县地区已知的其他德普福德/威尔明顿贝丘保持一致。研究推测，这些贝丘属于采蚝作业点，由少量个体集中加工大量牡蛎，用于盈余储存或对外交换。