The Geology of Colonial National Historical Park: River Terraces of the Virginia Peninsula

Colonial National Historical Park spans the Virginia Peninsula between the James and York rivers, in the city of Williamsburg and James and York counties, Virginia. It was established as Colonial National Monument on December 30, 1930, and renamed a national historical park on June 5, 1936. Its roughly 3,511 hectares (8,677 acres) protect places tied to the nation's beginnings, along with wetlands, upland forest, bluffs, fields, streams and shoreline.

Seven units

1. Historic Jamestown, site of America's first permanent English settlement, in 1607.
2. Yorktown Battlefield, scene of the culminating battle of the Revolutionary War in 1781.
3. The Colonial Parkway, 37 km (23 mi) long.
4. Green Spring Plantation.
5. Cape Henry Memorial, where the Jamestown colonists first landed in 1607.
6. Tyndall's Point.
7. Swann's Point.

Soft ground, stepped terraces

The park's geology is typical of the Coastal Plain. It is made mostly of soft sediments — loose to partly hardened — that were worn off the Appalachian Mountains to the west. These sediments build a thick wedge that extends the plain eastward, and the land is shaped into a series of step-like river terraces that drop in height toward the Chesapeake Bay.

The rocks and sediments range from the Miocene Eastover Formation, about 11 million years old, to recent deposits in salt marshes, swamps and rivers.

Part of the park's digital geologic map. National Park Service, Geologic Resources Inventory.

That ground has shaped the region's story from the start — for its prehistoric American Indian inhabitants, for the first European settlements, and through the struggles for independence and union in the Revolutionary and Civil wars.

Fossils

Many fossil species were first discovered, described and named from places within the park. The bivalve Chesapecten jeffersonius was probably the first fossil ever described in North America. All fossils in national parks are protected under the Paleontological Resources Preservation Act of 2009.

Fossil shells from Colonial National Historical Park. NPS photo by Melanie Peters.

Maps and reports

The NPS Geologic Resources Inventory has produced a scoping summary, digital geologic map and report for the park, and the NPS Soil Resources Inventory has completed a soil survey. All are available through the NPS DataStore.

Sources

• National Park Service: "NPS Geodiversity Atlas—Colonial National Historical Park, Virginia," citing Thornberry-Ehrlich (2016), Anderson (2017), Bailey (1999) and Ward and Blackwelder (1980).