"One of the major goals of President Obama's America's Great Outdoors initiative is to develop a conservation ethic for the 21st century," Salazar said in a statement.
"By designating these remarkable sites in Arizona, Colorado, Oregon, and Washington as national natural landmarks, we help establish and pass down to future generations those awe-inspiring places that make America truly beautiful."
Located on an isolated plateau at the confluence of the Deschutes and Crooked Rivers, The Island is a 208-acre (84-hectare) site that supports one of the best known and least disturbed examples of native juniper savanna within the Columbia Plateau.
The plateau is an arid steppe and grassland that covers portions of Washington, Oregon, Idaho, and Nevada, as well as a small piece of northeastern California, according to the U.S. Bureau of Land Management (BLM), which will jointly manage the site with the U.S. Forest Service.
The landmark is a remnant of the Palouse Prairie, the most altered—and most endangered—natural landscape in the inland Pacific Northwest, according to the U.S. Department of the Interior. About one percent of the original prairie remains, occurring only in small fragments found among developed areas.
Photograph courtesy Joseph Rocchio via National Park Service
Hanging Lake, Colorado
Hanging Lake is at the heart of the new Hanging Lake National Natural Landmark, part of the White River National Forest near Glenwood Springs, Colorado.
The 72-acre (29-hectare) site, a popular hiking spot, is an outstanding example of a lake formed during the creation of travertine, a crystalline form of calcite, according to the Department of the Interior.
This type of rock develops when calcium carbonate precipitates—or settles out—from mineral-rich water, so travertine is often found around hot springs and streams, according to Florida State University.
The Colorado lake and its associated waterfalls also support a rare wetland ecosystem, including hanging gardens.
Photograph courtesy J.B. Bell via National Park Service
Barfoot Park, Arizona
The newly named Barfoot Park National Natural Landmark lies in the Chiricahua Mountains of southern Arizona. The region supports an unusual mix of flora and fauna from the Sierra Madre and Rocky Mountain ranges.
The 680-acre (275-hectare) area, to be managed by the U.S. Forest Service, also includes three meadows, two permanent springs, and more than 15 acres (6 hectares) of talus slopes.
Talus is made of loose, angular rock fragments that accumulate at the base of a slope, according to the University of Wisconsin, Madison.
Round Top Butte National Natural Landmark includes a basaltic butte, flat volcanic plains, and small hills near Medford, Oregon. A butte is an isolated hill or small mountain with steep or precipitous sides and a top that can be variously flat, rounded, or pointed.
The new landmark's "exceptional" habitat is dominated by native bunchgrasses and contains a mix of dry grassland, Ponderosa pine, white oak, and buck brush.
The Round Top landmark encompasses 747 acres (302 hectares) spread across two sites: an established Research Natural Area managed by the BLM and a preserve overseen by the nonprofit The Nature Conservancy.
Photograph courtesy J. Kagan, National Park Service
Golden Fossil Areas, Colorado
A sign helps highlight an Iguanadon track along Dinosaur Ridge, a small slope in the mountains of Morrison, Colorado. The ridge is now part of the newly named Morrison-Golden Fossil Areas National Natural Landmark.
Among the most important paleontological sites in the western U.S., the 19-acre (8-hectare) region is one of the few places in the world that contains the combined fossil footprints of a variety of ancient reptiles, birds, and mammals.
Overall, "some of the landmarks are the best remaining examples of a type of feature in our nation—sometimes in the world—and we should continue to recognize and study these important natural features," National Park Service Director Jonathon B. Jarvis said in a statement.