The Shenandoah River: How It Shaped the Valley

Near the confluence of Cedar Creek and the North Fork of the Shenandoah River. NPS / Ann and Rob Simpson.

Cedar Creek and Belle Grove National Historical Park sits beside the meeting of Cedar Creek and the North Fork of the Shenandoah River. The whole Shenandoah system drains hundreds of square miles, fed by many streams like Cedar Creek.

The watershed

• Sources: headwaters high in the Blue Ridge and Alleghenies.
• Two forks: the North Fork and South Fork flow northeast and join just north of Front Royal, Virginia, forming the main stem.
• Into the Potomac: the river continues northeast to the Potomac at Harpers Ferry, West Virginia.
• "Lower" and "upper": because the river runs downhill to the northeast, the valley's northern end is the "lower" valley and the southern, upriver end the "upper" valley.
• To the sea: nearly every drop that falls on the valley, unless it evaporates, ends up in the Chesapeake Bay and the Atlantic Ocean — part of the Chesapeake Bay Watershed.

Erosion and deposition

• Carving the valley: over millions of years, the Shenandoah and its tributaries cut the Shenandoah Valley, picking up rock particles and dropping them to build wide, fertile floodplains.
• Meanders: shifting streams formed looping, snake-like meanders, many over soft shale — hardened clay, silt and mud.
• Soil: as weathering wore down the hills, the rivers spread the sediment across the valley. The soils come mostly from limestone, shale, siltstone and sandstone — but their richness comes from fertilizer-like limestone mixed with humus, decaying plant and animal matter.
• Farming: deep, fertile, well-drained soils grow grains, hay, timber, apples, peaches and pasture, and with ample rain, agriculture is still the valley's top industry.

Precipitation

Precipitation drives it all:

So the highlands keep wearing down, the rivers carry water and sediment downstream, caves grow, and the soil keeps producing crops — a cycle that appears stable.

Sources

Based on "Shenandoah River," Cedar Creek and Belle Grove National Historical Park, National Park Service; a work of the United States government in the public domain.