Soils

Soil is a three-dimensional body consisting of organic matter, mineral matter, air and water. Essentially, it is formed by rock weathering over long periods of time. Most soil found on the battlefield can be classified as the Hagerstown Series (soils are named after the area in which they are first discovered). Characteristics of every soil depend on multiple factors. First is the nature of the geologic material from which the soil is formed, or parent rock. This determines the texture and mineral content of the soil. Most of Antietam lies on a limestone foundation with some shale, sandstone, siltstone and dolomite. Second is relief (the lay of the land), which at Antietam consists of broad, rolling valleys. Relief affects drainage, aeration, runoff, erosion and exposure to sun and wind. The geology here causes it to be highly susceptible to these elements, resulting in soil that is classified as highly or potentially highly erodible. The third factor is climate, influencing the nature and extent of weathering. The climate of Washington County is the humid-temperate, continental type. Researchers believe, based on soil characteristics, that this climate had an impact on the formation of the soil since many of the area soils are acidic and strongly leached. The farm fields in the park are sprinkled with lime from time to time to neutralize the acid. Fourth, plant and animal life in and on the soil are an influential factor. The vegetation is generally responsible for the amount of nutrients. Burrowing animals, such as earthworms, cicadas, and others, help to keep the soil open and release nutrients for plant food. Since most of the battlefield has been used as farmland for well over a century, human activities have also had a significant impact on the surface soil layer. This leads into the final factor influencing soil characteristics, which is time. Over the years, records of the area document activities such as clearing forests, plowing land, adding fertilizers and moving soil materials from place to place. Each of these factors can significantly impact the make up of the soil and its fertility. It is critical for managers to understand and maintain soil integrity as it supports the elements of Antietam’s cultural landscape.