Name
Image
Date
Location
County
Ownership
Description
Boulder Park and McNeil Canyon Haystack Rocks
1986
47°52′43″N 119°48′06″W / 47.878611°N 119.801667°W / 47.878611; -119.801667
Douglas
Federal, state
The most illustrative examples of glacial erratics in the United States.
Davis Canyon
1986
48°14′38″N 119°45′06″W / 48.243775°N 119.751774°W / 48.243775; -119.751774
Okanogan
State, private
One of the largest and least disturbed examples of antelope bitterbrush-Idaho fescue shrub steppe remaining in the Columbia Plateau.
Drumheller Channels
1986
46°58′30″N 119°11′47″W / 46.975°N 119.196389°W / 46.975; -119.196389
Adams , Grant
Federal, state, private
Illustrates the dramatic modification of the Columbia Plateau volcanic terrain by late Pleistocene catastrophic glacial outburst floods. Includes Columbia National Wildlife Refuge .
Ginkgo Petrified Forest
1965
46°56′56″N 120°00′10″W / 46.948889°N 120.002778°W / 46.948889; -120.002778
Kittitas
State
Thousands of logs petrified in lava flows. Part of Ginkgo/Wanapum State Park.
Grand Coulee
1965
47°46′00″N 119°13′00″W / 47.766667°N 119.216667°W / 47.766667; -119.216667
Grant
Federal, state, private
An illustration of a series of geological events.
Grande Ronde Feeder Dikes
1980
Asotin
Private
The best example of basalt dikes, the congealed feeder sources of the Columbia River basalt plateau.
Grande Ronde Goosenecks
1980
Asotin
Federal
A 1,500-foot (460 m) deep canyon that follows a tortuous path along meanders.
The Great Gravel Bar of Moses Coulee
1986
47°27′30″N 119°48′00″W / 47.458333°N 119.8°W / 47.458333; -119.8 (Moses Coulee )
Douglas
State, private
Largest and best example of a pendent river bar formed by catastrophic glacial outburst floods that swept across the Columbia Plateau.
Kahlotus Ridgetop
2011
Franklin
State
The best remaining example of the Central Palouse Prairie grassland subtheme.
Mima Mounds
1966
46°53′N 123°03′W / 46.89°N 123.05°W / 46.89; -123.05 (Mima Mounds )
Thurston
State
A prairie containing unusual soil pimples of black silt-gravel.
Nisqually Delta
1971
47°06′31″N 122°42′11″W / 47.108611°N 122.703056°W / 47.108611; -122.703056 (Nisqually Delta )
Pierce , Thurston
Federal, state, tribal, private
An unusually fine example of an estuarine ecosystem. Includes Nisqually National Wildlife Refuge .
Point of Arches
1980
48°14′47″N 124°42′01″W / 48.2464503°N 124.7002419°W / 48.2464503; -124.7002419 (Point of Arches )
Clallam
Federal
An outstanding exhibit of sea action in sculpturing a rocky shoreline. A unit of Olympic National Park .
Rose Creek Preserve
1984
Whitman
Private
The best remaining example of the aspen phase of the hawthorne-cow parsnip habitat type in the Columbia Plateau. Managed by The Nature Conservancy .
Sims Corner Eskers and Kames
1986
47°49′30″N 119°22′00″W / 47.825°N 119.366667°W / 47.825; -119.366667
Douglas
Federal, state, private
The best examples in the Columbia Plateau of landforms resulting from stagnation and rapid retreat of the ice sheet during the last glaciation.
Steptoe and Kamiak Buttes
1965
47°01′57″N 117°17′55″W / 47.0325°N 117.298611°W / 47.0325; -117.298611
Whitman
State, county, private
Isolated mountain peaks of older rock surrounded by basalt, rising above the surrounding lava plateau.
Umtanum Ridge Water Gap
1980
46°51′00″N 120°32′40″W / 46.85°N 120.544444°W / 46.85; -120.544444
Kittitas
Federal, state, private
Geologic formation that illustrates the processes of tectonic folding and antecedent stream cutting.[ 1]
Wallula Gap
1980
46°02′40″N 118°56′48″W / 46.044444°N 118.946667°W / 46.044444; -118.946667
Benton , Walla Walla
Federal, state, county, municipal
The largest and most spectacular of several large water gaps through basalt anticlines in the Columbia River basin.
Withrow Moraine and Jameson Lake Drumlin Field
1980
47°41′15″N 119°37′29″W / 47.6875°N 119.624722°W / 47.6875; -119.624722
Douglas
Federal, private
The best examples of drumlins and the most illustrative segment of the only Pleistocene terminal moraine in the Columbia Plateau