Since at least seventy percent of Gwynns Falls/Leakin Park is forested, concern for the natural life is paramount. The predominant tree species are red oak, yellow (tulip) poplar and American Image beech. Yellow- poplars tend to predominate in the section of the park north of Dead Run, while there are more oaks and beeches in the southern section. White ash trees are also abundant in many areas, including the bottom lands where sycamore and red maples also grow. White oaks are generally confined to the ridge tops.

The park is wholly situated in the eastern division of the Piedmont. This physiographic province is characterized by the fall line on its eastern boundary, and a varied topography forms a diversified geology. Streams have steep gradients with rapids and falls and abrupt valley walls rise from the Gwynns Falls and Dead Run stream valleys. The topography along the stream beds is dramatic. There is an approximately 300-foot difference in elevation from the stream valleys to the ridge tops, where the highest elevation is 403 feet above sea level.

In order to maintain the wilderness (undeveloped) nature of Gwynns Falls/Leakin Park, all athletic and playground facilities are limited to the periphery.