National Natural Landmark in the context of "Grand Coulee"

Mona Island (Spanish: Isla de Mona) is the third-largest island of the Puerto Rican archipelago, after the main island of Puerto Rico and Vieques. It is the largest of three islands in the Mona Passage, the strait between Hispaniola and Puerto Rico, with the others being Monito Island and Desecheo Island. It measures about 7 miles by 4 miles (11 km by 7 km), and lies 41 mi (66 km) west of Puerto Rico, of which it is administratively a part. It is one of two islands that make up the Isla de Mona e Islote Monito barrio in the municipality of Mayagüez.

The island is managed under the Mona and Monito Islands Nature Reserve (Reserva Natural Islas de Mona y Monito). There are no permanent inhabitants; only rangers and biologists from the Puerto Rico Department of Natural and Environmental Resources reside on the island, to manage visitors and take part in research projects. The island, along with Monito, form part of the Mona and Monito Islands National Natural Landmark which recognizes and preserves the islands' ecosystem as an outstanding example of diversity and natural history. The island is home to a number of endemic species such as the Mona ground iguana and it is an important seabird area.

Lake Missoula was a prehistoric proglacial lake in western Montana that existed periodically at the end of the last ice age between 15,000 and 13,000 years ago. The lake measured about 7,770 square kilometres (3,000 sq mi) and contained about 2,100 cubic kilometres (500 cu mi) of water, half the volume of Lake Michigan.

The Glacial Lake Missoula National Natural Landmark is located about 110 kilometers (68 mi) northwest of Missoula, Montana, at the north end of the Camas Prairie Valley, just east of Montana Highway 382 and Macfarlane Ranch. It was designated as a National Natural Landmark in 1966 because it contains the great ripples (often measuring 25 to 50 feet (7.6 to 15.2 m) high and 300 feet (91 m) long) that served as a strong supporting element for J Harlen Bretz's contention that Washington State's Channeled Scablands were formed by repeated cataclysmic floods over only about 2,000 years, rather than through the millions of years of erosion that had been previously assumed.

Hell's Half Acre Lava Field is a basaltic lava plain located on the Snake River Plain of Idaho in the United States. It is the easternmost of the basaltic lava fields on the Snake River Plain, located about 25 miles (40 km) west of Idaho Falls, Idaho and 30 miles (48 km) north of Pocatello, Idaho. In 1976, the National Park Service designated the northwestern portion of the site a National Natural Landmark. In 1986, the Bureau of Land Management recommended that 68,760 acres (27,830 ha) of the site, located just southeast of the National Natural Landmark, to be a wilderness study area.

The Palisades, also called the New Jersey Palisades or the Hudson River Palisades, are a line of steep cliffs along the west side of the lower Hudson River in Northeastern New Jersey and Southeastern New York in the United States. The cliffs stretch north from Jersey City about 20 miles (32 km) to near Nyack, New York, and are visible at Haverstraw, New York. They rise nearly vertically from near the edge of the river, and are about 300 feet (90 m) high at Weehawken, increasing gradually to 540 feet (160 m) high near their northern terminus. North of Fort Lee, the Palisades are part of Palisades Interstate Park and are a National Natural Landmark.

The Palisades are among the most dramatic geologic features in the vicinity of New York City, forming a canyon of the Hudson north of the George Washington Bridge, as well as providing a vista of the Manhattan skyline. They sit in the Newark Basin, a rift basin located mostly in New Jersey.

La Brea Tar Pits comprise an active paleontological research site in urban Los Angeles. Hancock Park was formed around a group of tar pits where natural asphalt (also called asphaltum, bitumen, or pitch; brea in Spanish) has seeped up from the ground for tens of thousands of years. Over many centuries, the bones of trapped animals have been preserved. The George C. Page Museum is dedicated to researching the tar pits and displaying specimens from the animals that died there. "La Brea Tar Pits" is a registered National Natural Landmark.

The Falls of the Ohio National Wildlife Conservation Area is a national, bi-state area on the Ohio River near Louisville, Kentucky, in the United States, administered by the U.S. Army Corps of Engineers in partnership with the Indiana Department of Natural Resources. Federal status was awarded in 1981. The falls were designated a National Natural Landmark in 1966.

Mona Island (Spanish: Isla de Mona) is the third-largest island of the Puerto Rican archipelago, after the main island of Puerto Rico and Vieques. It is the largest of three islands in the Mona Passage, the strait between Hispaniola and Puerto Rico, with the others being Monito Island and Desecheo Island. It measures about 7 miles by 4 miles (11 km by 7 km), and lies 41 mi (66 km) west of Puerto Rico, of which it is administratively a part as one of two islands comprising the Isla de Mona e Islote Monito barrio in the municipality of Mayagüez.

The island is managed under the Mona and Monito Islands Nature Reserve (Reserva Natural Islas de Mona y Monito). There are no permanent inhabitants, as only rangers and biologists from the Puerto Rico Department of Natural and Environmental Resources temporarily reside on the island to manage visitors and take part in research projects. along with the neighboring island of Monito, it forms part of the Mona and Monito Islands National Natural Landmark which recognizes and preserves the ecosystem of the islands as an outstanding example of diversity and natural history. The island is home to a number of endemic species such as the Mona ground iguana, and it is an important seabird area.

The Sangamon River is a principal tributary of the Illinois River, approximately 246 miles (396 km) long, in central Illinois in the United States. It drains a mostly rural agricultural area and runs through Decatur and past Springfield. The river is associated with the early career of Abraham Lincoln, who was a sometime boatman working on the river, and played an important role in early European settlement of Illinois, when the area around was known as the "Sangamon River Country". The section of the Sangamon River that flows through Robert Allerton Park near Monticello was named a National Natural Landmark in 1971.