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Using Satellite Imagery and Soil Data To Understand Occurrences and Migration of Soil Conditions Harmful to Archaeological Sites on Jamestown Island, Virginia

Scientific Investigations Report 2025-5074
Prepared in cooperation with the National Park Service
By:
https://doi.org/10.3133/sir20255074

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Abstract

Many know Jamestown Island, Virginia, hereafter referred to as “the Island,” located near the mouth of the James River into the Chesapeake Bay, as the home of the first permanent English settlement in North America. However, the Island is home to 15,000 years’ worth of cultural artifacts and archaeological sites. In addition to its rich history, the Island is home to a variety of native plants and animals, including many rare, threatened, and endangered species. Preserving historical and natural resources is part of Colonial National Historic Park’s (COLO) enabling legislation. To this end, COLO has been seeking data to inform management decisions on how to prioritize resources to preserve archaeological sites and anticipate changes to natural systems from sea-level rise and other effects of climate change. The U.S. Geological Survey (USGS), in partnership with COLO, collected and analyzed data to help determine soil conditions detrimental to archaeological sites across the Island using a combination of soil samples and assessments of vegetative health as a proxy for soil conditions. This study combined normalized difference vegetative index raster grids spanning 8 years, 2010 to 2018, and soil data from 50 sites sampled in dry (June 2021) and wet months (March 2022) at two different soil horizons to investigate potential hazards to plant health and corrosive conditions in the unsaturated subsurface. The data suggest that access to the James River drives soil pH and soil conductivity. Areas of the Island that are subject to frequent inundation were observed to have both higher soil conductivity (as high as 4,845 millisiemens per meter [mS/m]) and lower pH (as low as 3.84). Higher soil conductivity, or salinity, and more acidity create corrosive environment, which can destroy buried artifacts and are detrimental to vegetative health. These conditions were not limited to the edges of the Island, like Black Point. Inland locations, such as the Pitch and Tar Swamp, were observed to have some of the highest conductivity values, which were likely caused by from a combination of inflow of James River water along Back Creek into the Pitch and Tar Swamp and proximity to the Visitor Center and other high-traffic areas of the Island. A difference of normalized difference vegetative index values from 2010 to 2018 raster grid appears to support this, showing an apparent loss of vegetative health in marsh grass in the Pitch and Tar Swamp. These data may inform COLO about areas of the Island that are currently most threatened by corrosive conditions and how those conditions are likely to migrate in the future.

Suggested Citation

Caldwell, S.H., 2025, Using satellite imagery and soil data to understand occurrences and migration of soil conditions harmful to archaeological sites on Jamestown Island, Virginia (ver. 1.1, November 2025): U.S. Geological Survey Scientific Investigations Report 2025–5074, 22 p., https://doi.org/10.3133/sir20255074.

ISSN: 2328-0328 (online)

ISSN: 2328-031X (print)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Purpose and Scope
  • Study Area Description
  • Methods
  • Results
  • Summary
  • Acknowledgments
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Using satellite imagery and soil data to understand occurrences and migration of soil conditions harmful to archaeological sites on Jamestown Island, Virginia
Series title Scientific Investigations Report
Series number 2025-5074
ISBN 978-1-4113-4629-1
DOI 10.3133/sir20255074
Edition Version 1.0: September 16, 2025; Version 1.1: September 30, 2025
Publication Date September 16, 2025
Year Published 2025
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Virginia and West Virginia Water Science Center
Description Report: vii, 22 p.; Data Release
Country United States
State Virginia
Other Geospatial Jamestown Island
Online Only (Y/N) N
Additional Online Files (Y/N) N
Additional publication details