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About 18,000 years ago, Whidbey Island lay under roughly 1,250 meters (4,100 feet) of ice. What that ice left behind decided where people would farm, build a fort, harbor boats, grow mussels and land planes — and that history is what Ebey's Landing National Historical Reserve exists to protect.
Authorized in 1978 as the first national historical reserve in the National Park System, it preserves an unbroken record of Puget Sound exploration and settlement from the 19th century to today. It lies on Whidbey Island, the largest island in the conterminous United States, about 43 km (27 miles) north of Seattle, and is managed by members of the central Whidbey community together with local, state and federal governments.
The landscape of Ebey's Landing. From the National Park Service's Geologic Resources Inventory gallery.
Made by glaciers
The reserve sits in the Puget Lowland, a broad, low region between the Cascade Range to the east and the Olympic Mountains to the west. As in the San Juan Islands, continental glaciers of the Pleistocene ice ages shaped the land. Glacial and non-glacial layers of clay, silt, sand and gravel record several advances and retreats of ice through the lowland. When the last glaciers melted they left a mix of loose sediments from glaciomarine seafloors, deltas, outwash plains carried by rivers, and the edges and undersides of the ice.
From landform to landmark
| Landform | How it formed | What people made of it |
|---|---|---|
| Western bluffs | Shaped by glaciers | A vantage point for Fort Casey, built in the late 1890s and now a state park |
| San de Fuca Uplands | Glacial till | Rolling hills and farmland |
| Ebey's Prairie | Clayey glaciomarine drift and gentle slopes | Rich soils farmed by American Indians and by farmers today |
| Smith Prairie | A well-drained, raised, flat delta built into a glacial lake | The Coupeville airfield |
| Penn Cove | A trough carved by fast, pressurized meltwater flowing under the ice | A sheltered harbor for Coupeville and an ideal place to grow mussels |
| Kettle and Pratt Woodlands | Kettle ponds, left where stagnant ice melted | The landscape around Fort Ebey State Park |
Together with the island's distinctive climate, its rain-shadow location, its soils and the influence of the sea, these features shaped both the historic landscape and an unusual diversity of plants, animals and habitats.
A fault next door
Whidbey Island is tectonically active, and sudden land-level changes during earthquakes have been documented inside the reserve. The northwest-trending Southern Whidbey Island fault runs 10 km (6 miles) southeast of Admiralty Head, the reserve's southwestern corner. It separates two major blocks of the Earth's crust and has caused several shallow earthquakes in historic times, and faults outside the reserve have moved as recently as 1850 C.E.
Most of the reserve is pastoral, but ground shaking and land-level change threaten the historic buildings of Coupeville — the second-oldest town in Washington and the reserve's commercial center — which stands on clayey glaciomarine drift that may not give a firm foundation in an earthquake.
Studying the reserve's geology
- Fossils: all fossils in national parks are protected under the Paleontological Resources Preservation Act of 2009.
- Regional setting: the reserve belongs to the Pacific Border physiographic province, sharing its geologic history with a region far beyond its boundaries.
- Maps and reports: the Geologic Resources Inventory, which produces digital geologic maps and reports for more than 270 natural resource parks, has published a report and map for the reserve, and a Soil Resources Inventory has been completed; both are on the NPS DataStore.
Sources
Based on "NPS Geodiversity Atlas—Ebey's Landing National Historical Reserve, Washington," National Park Service Geologic Resources Inventory; a work of the United States government in the public domain.
Licença: CC0 1.0 (domínio público) · Adaptado de www.nps.gov
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