USGS: The River and The Rocks (A Few Words About the Forests)

THE RIVER AND THE ROCKS

The Geologic Story of Great Falls and the Potomac River Gorge

A FEW WORDS ABOUT THE FORESTS

The original forests of Great Falls Park have been almost completely cut over since 1790; only a few trees on the hill north of Difficult Run remain from presettlement times. After repeated cutting and clearing, fires, and high water, the bulk of the forest lands now supports second- or third-growth trees.

The various types of plants growing in the area reflect differences in landscape features and the availability of water. Forty-three species of trees have been recognized; their distribution and the associated groupings of shrubs and wild flowers for the five major subdivisions of the forest landscape are summarized in the following table.

Although the nature of the presettlement forests is not known, the present confinement of certain trees and shrubs to specific environments suggests that the bulk of the plant cover, except for the age and size of trees, is much like it was more than 150 years ago. A recent change in the forest is the disappearance of chestnut trees from the piedmont uplands because of the chestnut blight.

The sketches of leaves shown in the trail logs have been added to assist you in identifying the numerous species of trees growing in the park.

Landscape features and forest subdivisions


Landscape features	Forest subdivisions			Appearance	Environmental influence
Landscape features	Prominent species	Other species	Small trees and shrubs	Appearance	Environmental influence

Flood plains	Sycamore Green ash	Elm Boxelder Silver maple River birch Cottonwood	American hornbeam Spicebush Pawpaw Silky cornel	White trunks and branches of sycamore are typical.	Floods at least once every two years.

Bedrock terrace	Post oak Red oak	Virginia pine Pignut hickory White oak Chestnut oak Redcedar	Blueberries American holly Dogwood Fringetree Mountain-holly	Small, stunted, heavily branched trees.	Rocky ground of Bear Island and along cliffs. Rarely floods.

Piedmont uplands	White oak Black oak	Red oak Scarlet oak Chestnut oak Southern Red oak Yellow poplar Virginia pine Shortleaf pine	Mountain-laurel Dogwood Shadbush Mapleleaf viburnum	Variable: from small, second-growth saplings to tall, straight-trunked large trees; dense to open undergrowth.	Hills and slopes underlain by deep soil. Never floods.

Swamps	Red maple Oaks	Pin oak Willow oak Swamp white oak Sourgum	Spicebush Southern arrowroot Poison-sumac Alder	Dense tangle of shrubs.	Poorly drained depressions and low areas. Water close to surface or standing. Floods rarely on Bear Island.

Areas of past use	Box elder Elm Black locust	Yellow poplar Honey locust Black walnut	Spicebush Japanese honeysuckle "Escaped" cultivated shrubs	Bent, poorly formed trees; weedy ground.	Intense activity by man at Matilda villeand around canal lockhouses.

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Last Updated: 01-Mar-2005