There is only one mapped stand of Acidic Oak – Hickory Forest in Harpers Ferry National Historical Park. It’s on a west- to southwest-facing slope that overlooks the Potomac and a small tributary of the Potomac. The underlying bedrock is Harpers Formation, which consists of metamorphosed siltstone and sandstone. The soil is very acidic, but has slightly more nutrients available for plants than do the infertile soils in the park’s Chestnut Oak Forest, for instance.