National Capital Parks-East - Soils

Major soil associations that occur within National Capital Parks-East include the Sassafras-Keyport-Elkton Association situated on the terraces along the Potomac River and Piscataway Creek and the Sassafras-Croom and Christiana-Chillum Associations located on the slopes and gullies of the inland portions of the parks. The predominant soil association at Greenbelt Park is the Christiana-Sunnyside-Beltsville. Soils in the Sassafras-Keyport-Elkton Association at Piscataway Park tend to be more poorly drained because of thick beds of silty clay beneath the Keyport and Elkton soil types. The Sassafras-Croom Association tends to have soils that are more well drained because of their high sand and gravel content. Most of the soils have a pH ranging from 4.0 to 5.5, but one soil, Ochlockonee sandy loam local alluvium occurring on 2 to 5 percent slopes, had a pH ranging from 5.1-6.0. Although not documented by soil survey maps the many ravines created by Accokeek Creek and its tributaries within Piscataway Park have cut deeply into the Sassafras-Croom association exposing the underlying Paleocene fossil deposits which abound in the glauconite rich gray clay substrata. The high levels of calcium carbonate shell material in these soils give them a circumneutral pH and an associated calciphilic flora uncharacteristic of the Maryland Coastal Plain. Areas within Johnsons Gully, the Reserve Road Ravine, and the ravines in Fort Washington Park have similar circumneutral soils.