Lake and Peninsula County, Alaska
Aniakchak is an extant volcano. The caldera formed during a major eruption in 1645 B.C. The most recent eruption was in 1931. Surprise Lake within the caldera is the source of the Aniakchak River, a National Wild River.
This remote place is perhaps the least visited unit of the National Park System. The national monument is 137,176 federal acres (555 km2) and the preserve is 465,603 acres (1,884 km2) of which 439,863 are federal.
Union, Boone County, Kentucky, 41091
The name of Big Bone Lick State Park comes from the Pleistocene megafauna fossils found there. Mammoths are believed to have been drawn to this location by a salt lick deposited around sulphur springs.
Grizzly Ridge, Colorado
This unique and spectacular landscape was formed slowly by the action of water and rock scouring down through hard Proterozoic crystalline rock. No other canyon in North America has such narrow opening, sheer walls, and startling depths.
Cape Krusenstern National Monument stretches 70 miles along the Chukchi Sea shoreline. It is made up mainly of a coastal plain, containing large lagoons and rolling hills of limestone. Beach ridges provide evidence of 5000 years of human activity.
Morrill County, Nebraska, 69334
Chimney Rock is a prominent geological rock formation. Rising nearly 300 feet (91 m) above the surrounding North Platte River valley, the peak of Chimney Rock is 4,226 feet (1,288 m) above sea level.
Malta, Cassia County, Idaho, 83342
The City of Rocks is an area of rock spires and formations and is a popular rock climbing area. The landscape has been sculpted from granite that has eroded into a fascinating assortment of shapes.
Arco, Butte County, Idaho
The protected area's features are volcanic and represent one of the best preserved flood basalt areas in the continental United States. It is composed of encompass three major lava fields and about 400 square miles (1,036 km2) of sagebrush steppe grasslan
Crook County, Wyoming
Devil's Tower rises 1267 feet (386 m) above the surrounding land and is part of the United States first official National Monument. It played a large role in the movie "Close Encounters of the Third Kind."
Dotsero, Eagle County, Colorado, 81637
Dotsero is a 700 meter wide by 400 meter deep maar volcano (broad, low relief crater). Erupting approximately 4200 years ago, it is the youngest volcano in Colorado. It is currently dormant.
To commemorate the long history of peace and friendship between the United States and Canada, the two nations have combined Glacier National Park and Waterton Lakes National Park and created the Waterton/Glacier International Peace Park.
The Great Lakes are the world's largest group of fresh water lakes and are part of the St. Lawrence System, the largest fresh water system in the world. Because of their size, the Great Lakes are often called inland seas.
Hells Canyon is a 10-mile (16 km) wide canyon located along the border of eastern Oregon, eastern Washington and western Idaho in the United States. It is North America's deepest river gorge at 7,993 feet (2,436 m).
The site was formerly known as the Canyon Diablo Crater, and scientists generally refer to it as Barringer Crater in honor of Daniel Barringer who was first to suggest that it was produced by meteorite impact.
Only about 2000 feet (600 m) above sea level, Mount Adagdak consists of a small stratovolcano capping an older shield volcano. The date of its last known eruption is unknown, but a basaltic lava dome was constructed on the southeast side.
Skamania County, Washington
In 1982, the 110,000-acre Mount St. Helens National Volcanic Monument was created for research, recreation, and education. Inside the Monument, the environment is left to respond naturally in recovering from the 1980 eruption and any future disturbance.
The mountain is a volcanic feature known as a trachyte plug. This means that it is a volcanic intrusion made of extrusive igneous rocks and minerals which have a fine-grained, generally porphyritic texture.
With an area of 112,512 acres (45,500 ha), the parks protect 45% of the remaining groves of coastal redwood (Sequoia sempervirens) trees, the tallest and one of the most massive tree species on Earth.
The park was established as Saguaro National Monument on March 1, 1933 and changed to a national park on October 14, 1994. The total area of Saguaro National Park in 2002 was 143 square miles (370 km2) of which 111 square miles.
Shoshone, Lincoln County, Idaho, 83352
Once a source of ice for the town of Shoshone, these lava tube caves are not the most interesting, but there are legends that they are haunted by the Indian Princess Edahow who was buried in the ice.
Coconino County, Arizona
Sunset Crater was named for its brilliantly colored scoria deposits mantling the cone. Having erupted sometime between 1080 and 1150 AD, it is the youngest of the more than 550 vents of the vast San Francisco volcanic field.
This New Mexico site comprises the southern part of a 275 square miles (710 km2) field of white sand dunes composed of gypsum crystals. Gypsum is rarely found in the form of sand because it is water-soluble.
Set aside as a national park on March 1, 1872, Yellowstone was the first National Park and is known for its wildlife and geothermal features, especially Old Faithful Geyser, one of the most popular areas in the park.