Geophysical Investigations at the Nezekaw Terrace Mound Group (Site 13AM82), Effigy Mounds National Monument, Allamakee County, Iowa

The National Park Service’s Midwest Archeological Center and Effigy Mounds National Monument staffs with the University of Nebraska-Lincoln graduate student and the Volunteer-In-Parks participants conducted geophysical investigations at the Nezekaw Terrace Mound Group (Site 13AM82) located on the Effigy Mounds National Monument in Allamakee County, Iowa. The geophysical investigations were conducted between June 8 and 14, 2008. The archeological investigations were requested by an anthropology graduate student at the University of Nebraska-Lincoln as part of his Masters Thesis archeological project at Effigy Mounds National Monument. The project was located within the Yellow River or North Unit of the park on the east side of the visitors center above the confluence of the Mississippi River and the Yellow River.
During the investigations, 3,721 square meters or 0.92 acres were surveyed with a single fluxgate gradiometer and a dual fluxgate gradiometer system, a conductivity meter, a resistance meter and twin probe array, and a ground penetrating radar cart system with a 400 mHz antenna. The geophysical project was divided into two units, EFMO1 and EFMO2, which were separated by an upland drainageway. The geophysical data collected at the selected project areas provided information of the physical properties of the subsurface materials. Several geophysical anomalies were identified during the investigation of the two project areas. The resistance, ground penetrating radar, magnetic, and conductivity anomalies represented the outlines of buried mound remnants at EFMO1, while the integrity of the two mounds at EFMO2 was also documented as a result of the magnetic, resistance, and conductivity surveys within the survey area. It is recommended that additional geophysical investigations be undertaken at the Nezekaw Terrace Mound Group to identify buried archeological resources associated with the geophysical anomalies identified at the National Park Service unit.

美国国家公园管理局（National Park Service）中西部考古中心、象形土丘国家纪念碑（Effigy Mounds National Monument）的工作人员，联合内布拉斯加大学林肯分校（University of Nebraska-Lincoln）的研究生以及公园志愿服务者（Volunteer-In-Parks），在位于爱荷华州阿拉马基县的象形土丘国家纪念碑内的内泽考台地土丘群（遗址编号13AM82）开展了地球物理勘探工作，勘探时间为2008年6月8日至14日。本次考古勘探由内布拉斯加大学林肯分校的一名人类学研究生发起，作为其在象形土丘国家纪念碑开展的硕士学位论文（Masters Thesis）考古研究项目的一部分。项目区域位于公园黄河片区（北单元）的游客中心东侧、密西西比河与黄河汇流处上方的高地范围内。
本次勘探使用单通道磁通门梯度仪（fluxgate gradiometer）、双通道磁通门梯度仪系统、电导仪（conductivity meter）、电阻率仪（resistance meter）及双探头阵列，以及搭载400兆赫兹（mHz）天线的探地雷达（ground penetrating radar）车系统，共完成3721平方米（约合0.92英亩）的勘测作业。本次地球物理勘探项目分为EFMO1与EFMO2两个作业单元，两个单元以高地排水沟为界。在选定作业区域采集的地球物理数据，可反映地下介质的物理特性。本次勘探共识别出多处地球物理异常：EFMO1区域的电阻率、探地雷达、磁法及电导异常，对应了被掩埋的土丘残迹轮廓；EFMO2区域的磁法、电阻率及电导勘探结果，则证实了区内两座土丘的完整性。建议对内泽考台地土丘群开展补充地球物理勘探，以识别本次在国家公园管理局辖区内发现的、与地球物理异常相关的埋藏考古遗存。